import "github.com/go-playground/validator/v10"

Package validator implements value validations for structs and individual fields based on tags.

It can also handle Cross-Field and Cross-Struct validation for nested structs and has the ability to dive into arrays and maps of any type.

see more examples https://github.com/go-playground/validator/tree/master/_examples

Singleton

Validator is designed to be thread-safe and used as a singleton instance. It caches information about your struct and validations, in essence only parsing your validation tags once per struct type. Using multiple instances neglects the benefit of caching. The not thread-safe functions are explicitly marked as such in the documentation.

Validation Functions Return Type error

Doing things this way is actually the way the standard library does, see the file.Open method here:

https://golang.org/pkg/os/#Open.

The authors return type "error" to avoid the issue discussed in the following, where err is always != nil:

http://stackoverflow.com/a/29138676/3158232
https://github.com/go-playground/validator/issues/134

Validator only InvalidValidationError for bad validation input, nil or ValidationErrors as type error; so, in your code all you need to do is check if the error returned is not nil, and if it's not check if error is InvalidValidationError ( if necessary, most of the time it isn't ) type cast it to type ValidationErrors like so err.(validator.ValidationErrors).

Custom Validation Functions

Custom Validation functions can be added. Example:

// Structure
func customFunc(fl validator.FieldLevel) bool {

	if fl.Field().String() == "invalid" {
		return false
	}

	return true
}

validate.RegisterValidation("custom tag name", customFunc)
// NOTES: using the same tag name as an existing function
//        will overwrite the existing one

Valuer Interface

Custom types can implement the Valuer interface to return the value that should be validated. This is useful when a type wraps another value and you want validation to run against the unwrapped value.

type Nullable[T any] struct {
	Data T
}

func (n Nullable[T]) ValidatorValue() any {
	return n.Data
}

type Config struct {
	Name string `validate:"required"`
}

type Record struct {
	Config Nullable[Config] `validate:"required"`
}

r := Record{
	Config: Nullable[Config]{
		Data: Config{Name: "validator"},
	},
}

err := validate.Struct(r)

The library also supports types like sql/driver.Valuer using RegisterCustomTypeFunc. See _examples/valuer/main.go and _examples/custom/main.go for both approaches.

Cross-Field Validation

Cross-Field Validation can be done via the following tags:

eqfield
nefield
gtfield
gtefield
ltfield
ltefield
eqcsfield
necsfield
gtcsfield
gtecsfield
ltcsfield
ltecsfield

If, however, some custom cross-field validation is required, it can be done using a custom validation.

Why not just have cross-fields validation tags (i.e. only eqcsfield and not eqfield)?

The reason is efficiency. If you want to check a field within the same struct "eqfield" only has to find the field on the same struct (1 level). But, if we used "eqcsfield" it could be multiple levels down. Example:

type Inner struct {
	StartDate time.Time
}

type Outer struct {
	InnerStructField *Inner
	CreatedAt time.Time      `validate:"ltecsfield=InnerStructField.StartDate"`
}

now := time.Now()

inner := &Inner{
	StartDate: now,
}

outer := &Outer{
	InnerStructField: inner,
	CreatedAt: now,
}

errs := validate.Struct(outer)

// NOTE: when calling validate.Struct(val) topStruct will be the top level struct passed
//       into the function
//       when calling validate.VarWithValue(val, field, tag) val will be
//       whatever you pass, struct, field...
//       when calling validate.Field(field, tag) val will be nil

Multiple Validators

Multiple validators on a field will process in the order defined. Example:

type Test struct {
	Field `validate:"max=10,min=1"`
}

// max will be checked then min

Bad Validator definitions are not handled by the library. Example:

type Test struct {
	Field `validate:"min=10,max=0"`
}

// this definition of min max will never succeed

Using Validator Tags

Baked In Cross-Field validation only compares fields on the same struct. If Cross-Field + Cross-Struct validation is needed you should implement your own custom validator.

Comma (",") is the default separator of validation tags. If you wish to have a comma included within the parameter (i.e. excludesall=,) you will need to use the UTF-8 hex representation 0x2C, which is replaced in the code as a comma, so the above will become excludesall=0x2C.

type Test struct {
	Field `validate:"excludesall=,"`    // BAD! Do not include a comma.
	Field `validate:"excludesall=0x2C"` // GOOD! Use the UTF-8 hex representation.
}

Pipe ("|") is the 'or' validation tags deparator. If you wish to have a pipe included within the parameter i.e. excludesall=| you will need to use the UTF-8 hex representation 0x7C, which is replaced in the code as a pipe, so the above will become excludesall=0x7C

type Test struct {
	Field `validate:"excludesall=|"`    // BAD! Do not include a pipe!
	Field `validate:"excludesall=0x7C"` // GOOD! Use the UTF-8 hex representation.
}

Build tags

The library provides a build tag for build size optimizations. If you are not using validateFn you can add the validator_novalidatefn build tag to enabled better dead code elimination. With this build tag, any usage of validateFn tags will panic.

Baked In Validators and Tags

Here is a list of the current built in validators:

Skip Field

Tells the validation to skip this struct field; this is particularly handy in ignoring embedded structs from being validated. (Usage: -)

Usage: -

Or Operator

This is the 'or' operator allowing multiple validators to be used and accepted. (Usage: rgb|rgba) <-- this would allow either rgb or rgba colors to be accepted. This can also be combined with 'and' for example ( Usage: omitempty,rgb|rgba)

Usage: |

StructOnly

When a field that is a nested struct is encountered, and contains this flag any validation on the nested struct will be run, but none of the nested struct fields will be validated. This is useful if inside of your program you know the struct will be valid, but need to verify it has been assigned. NOTE: only "required" and "omitempty" can be used on a struct itself.

Usage: structonly

NoStructLevel

Same as structonly tag except that any struct level validations will not run.

Usage: nostructlevel

Omit Empty

Allows conditional validation, for example, if a field is not set with a value (Determined by the "required" validator) then other validation such as min or max won't run, but if a value is set validation will run.

Usage: omitempty

Omit Nil

Allows to skip the validation if the value is nil (same as omitempty, but only for the nil-values).

Usage: omitnil

Omit Zero

Allows to skip the validation if the value is a zero value. For pointers, it checks if the pointer is nil or the underlying value is a zero value. For slices and maps, it checks if the value is nil or empty. Otherwise, behaves the same as omitempty.

Usage: omitzero

Dive

This tells the validator to dive into a slice, array or map and validate that level of the slice, array or map with the validation tags that follow. Multidimensional nesting is also supported, each level you wish to dive will require another dive tag. dive has some sub-tags, 'keys' & 'endkeys', please see the Keys & EndKeys section just below.

Usage: dive

Example #1

[][]string with validation tag "gt=0,dive,len=1,dive,required"
// gt=0 will be applied to []
// len=1 will be applied to []string
// required will be applied to string

Example #2

[][]string with validation tag "gt=0,dive,dive,required"
// gt=0 will be applied to []
// []string will be spared validation
// required will be applied to string

Keys & EndKeys

These are to be used together directly after the dive tag and tells the validator that anything between 'keys' and 'endkeys' applies to the keys of a map and not the values; think of it like the 'dive' tag, but for map keys instead of values. Multidimensional nesting is also supported, each level you wish to validate will require another 'keys' and 'endkeys' tag. These tags are only valid for maps.

Usage: dive,keys,othertagvalidation(s),endkeys,valuevalidationtags

Example #1

map[string]string with validation tag "gt=0,dive,keys,eq=1|eq=2,endkeys,required"
// gt=0 will be applied to the map itself
// eq=1|eq=2 will be applied to the map keys
// required will be applied to map values

Example #2

map[[2]string]string with validation tag "gt=0,dive,keys,dive,eq=1|eq=2,endkeys,required"
// gt=0 will be applied to the map itself
// eq=1|eq=2 will be applied to each array element in the map keys
// required will be applied to map values

Required

This validates that the value is not the data types default zero value. For numbers ensures value is not zero. For strings ensures value is not "". For booleans ensures value is not false. For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value when using WithRequiredStructEnabled.

Usage: required

Required If

The field under validation must be present and not empty only if all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value. Using the same field name multiple times in the parameters will result in a panic at runtime.

Usage: required_if

Examples:

// require the field if the Field1 is equal to the parameter given:
Usage: required_if=Field1 foobar

// require the field if the Field1 and Field2 is equal to the value respectively:
Usage: required_if=Field1 foo Field2 bar

Required Unless

The field under validation must be present and not empty unless all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: required_unless

Examples:

// require the field unless the Field1 is equal to the parameter given:
Usage: required_unless=Field1 foobar

// require the field unless the Field1 and Field2 is equal to the value respectively:
Usage: required_unless=Field1 foo Field2 bar

Required With

The field under validation must be present and not empty only if any of the other specified fields are present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: required_with

Examples:

// require the field if the Field1 is present:
Usage: required_with=Field1

// require the field if the Field1 or Field2 is present:
Usage: required_with=Field1 Field2

Required With All

The field under validation must be present and not empty only if all of the other specified fields are present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: required_with_all

Example:

// require the field if the Field1 and Field2 is present:
Usage: required_with_all=Field1 Field2

Required Without

The field under validation must be present and not empty only when any of the other specified fields are not present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: required_without

Examples:

// require the field if the Field1 is not present:
Usage: required_without=Field1

// require the field if the Field1 or Field2 is not present:
Usage: required_without=Field1 Field2

Required Without All

The field under validation must be present and not empty only when all of the other specified fields are not present. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: required_without_all

Example:

// require the field if the Field1 and Field2 is not present:
Usage: required_without_all=Field1 Field2

Excluded If

The field under validation must not be present or not empty only if all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: excluded_if

Examples:

// exclude the field if the Field1 is equal to the parameter given:
Usage: excluded_if=Field1 foobar

// exclude the field if the Field1 and Field2 is equal to the value respectively:
Usage: excluded_if=Field1 foo Field2 bar

Excluded Unless

The field under validation must not be present or empty unless all the other specified fields are equal to the value following the specified field. For strings ensures value is not "". For slices, maps, pointers, interfaces, channels and functions ensures the value is not nil. For structs ensures value is not the zero value.

Usage: excluded_unless

Examples:

// exclude the field unless the Field1 is equal to the parameter given:
Usage: excluded_unless=Field1 foobar

// exclude the field unless the Field1 and Field2 is equal to the value respectively:
Usage: excluded_unless=Field1 foo Field2 bar

Is Default

This validates that the value is the default value and is almost the opposite of required.

Usage: isdefault

Length

For numbers, length will ensure that the value is equal to the parameter given. For strings, it checks that the string length is exactly that number of characters. For slices, arrays, and maps, validates the number of items.

Example #1

Usage: len=10

Example #2 (time.Duration)

For time.Duration, len will ensure that the value is equal to the duration given in the parameter.

Usage: len=1h30m

Maximum

For numbers, max will ensure that the value is less than or equal to the parameter given. For strings, it checks that the string length is at most that number of characters. For slices, arrays, and maps, validates the number of items.

Example #1

Usage: max=10

Example #2 (time.Duration)

For time.Duration, max will ensure that the value is less than or equal to the duration given in the parameter.

Usage: max=1h30m

Minimum

For numbers, min will ensure that the value is greater or equal to the parameter given. For strings, it checks that the string length is at least that number of characters. For slices, arrays, and maps, validates the number of items.

Example #1

Usage: min=10

Example #2 (time.Duration)

For time.Duration, min will ensure that the value is greater than or equal to the duration given in the parameter.

Usage: min=1h30m

Equals

For strings & numbers, eq will ensure that the value is equal to the parameter given. For slices, arrays, and maps, validates the number of items.

Example #1

Usage: eq=10

Example #2 (time.Duration)

For time.Duration, eq will ensure that the value is equal to the duration given in the parameter.

Usage: eq=1h30m

Not Equal

For strings & numbers, ne will ensure that the value is not equal to the parameter given. For slices, arrays, and maps, validates the number of items.

Example #1

Usage: ne=10

Example #2 (time.Duration)

For time.Duration, ne will ensure that the value is not equal to the duration given in the parameter.

Usage: ne=1h30m

One Of

For strings, ints, and uints, oneof will ensure that the value is one of the values in the parameter. The parameter should be a list of values separated by whitespace. Values may be strings or numbers. To match strings with spaces in them, include the target string between single quotes. Kind of like an 'enum'.

Usage: oneof=red green
       oneof='red green' 'blue yellow'
       oneof=5 7 9

One Of Case Insensitive

Works the same as oneof but is case insensitive and therefore only accepts strings.

Usage: oneofci=red green
       oneofci='red green' 'blue yellow'

None Of

For strings, ints, and uints, noneof will ensure that the value is not one of the values in the parameter. The parameter should be a list of values separated by whitespace. Values may be strings or numbers. To inversely match strings with spaces in them, include the target string between single quotes. Kind of like an 'enum'.

Usage: noneof=red green
       noneof='red green' 'blue yellow'
	   noneof=5 7 9

None Of Case Insensitive

Works the same as noneof but is case insensitive and therefore only accepts strings.

Usage: noneofci=red green
       noneofci='red green' 'blue yellow'

Greater Than

For numbers, this will ensure that the value is greater than the parameter given. For strings, it checks that the string length is greater than that number of characters. For slices, arrays and maps it validates the number of items.

Example #1

Usage: gt=10

Example #2 (time.Time)

For time.Time ensures the time value is greater than time.Now.UTC().

Usage: gt

Example #3 (time.Duration)

For time.Duration, gt will ensure that the value is greater than the duration given in the parameter.

Usage: gt=1h30m

Greater Than or Equal

Same as 'min' above. Kept both to make terminology with 'len' easier.

Example #1

Usage: gte=10

Example #2 (time.Time)

For time.Time ensures the time value is greater than or equal to time.Now.UTC().

Usage: gte

Example #3 (time.Duration)

For time.Duration, gte will ensure that the value is greater than or equal to the duration given in the parameter.

Usage: gte=1h30m

Less Than

For numbers, this will ensure that the value is less than the parameter given. For strings, it checks that the string length is less than that number of characters. For slices, arrays, and maps it validates the number of items.

Example #1

Usage: lt=10

Example #2 (time.Time)

For time.Time ensures the time value is less than time.Now.UTC().

Usage: lt

Example #3 (time.Duration)

For time.Duration, lt will ensure that the value is less than the duration given in the parameter.

Usage: lt=1h30m

Less Than or Equal

Same as 'max' above. Kept both to make terminology with 'len' easier.

Example #1

Usage: lte=10

Example #2 (time.Time)

For time.Time ensures the time value is less than or equal to time.Now.UTC().

Usage: lte

Example #3 (time.Duration)

For time.Duration, lte will ensure that the value is less than or equal to the duration given in the parameter.

Usage: lte=1h30m

Field Equals Another Field

This will validate the field value against another fields value either within a struct or passed in field.

Example #1:

// Validation on Password field using:
Usage: eqfield=ConfirmPassword

Example #2:

// Validating by field:
validate.VarWithValue(password, confirmpassword, "eqfield")

Field Equals Another Field (relative)

This does the same as eqfield except that it validates the field provided relative to the top level struct.

Usage: eqcsfield=InnerStructField.Field)

Field Does Not Equal Another Field

This will validate the field value against another fields value either within a struct or passed in field.

Examples:

// Confirm two colors are not the same:
//
// Validation on Color field:
Usage: nefield=Color2

// Validating by field:
validate.VarWithValue(color1, color2, "nefield")

Field Does Not Equal Another Field (relative)

This does the same as nefield except that it validates the field provided relative to the top level struct.

Usage: necsfield=InnerStructField.Field

Field Greater Than Another Field

Only valid for Numbers, time.Duration and time.Time types, this will validate the field value against another fields value either within a struct or passed in field. usage examples are for validation of a Start and End date:

Example #1:

// Validation on End field using:
validate.Struct Usage(gtfield=Start)

Example #2:

// Validating by field:
validate.VarWithValue(start, end, "gtfield")

Field Greater Than Another Relative Field

This does the same as gtfield except that it validates the field provided relative to the top level struct.

Usage: gtcsfield=InnerStructField.Field

Field Greater Than or Equal To Another Field

Example #1:

// Validation on End field using:
validate.Struct Usage(gtefield=Start)

Example #2:

// Validating by field:
validate.VarWithValue(start, end, "gtefield")

Field Greater Than or Equal To Another Relative Field

This does the same as gtefield except that it validates the field provided relative to the top level struct.

Usage: gtecsfield=InnerStructField.Field

Less Than Another Field

Example #1:

// Validation on End field using:
validate.Struct Usage(ltfield=Start)

Example #2:

// Validating by field:
validate.VarWithValue(start, end, "ltfield")

Less Than Another Relative Field

This does the same as ltfield except that it validates the field provided relative to the top level struct.

Usage: ltcsfield=InnerStructField.Field

Less Than or Equal To Another Field

Example #1:

// Validation on End field using:
validate.Struct Usage(ltefield=Start)

Example #2:

// Validating by field:
validate.VarWithValue(start, end, "ltefield")

Less Than or Equal To Another Relative Field

This does the same as ltefield except that it validates the field provided relative to the top level struct.

Usage: ltecsfield=InnerStructField.Field

Field Contains Another Field

This does the same as contains except for struct fields. It should only be used with string types. See the behavior of reflect.Value.String() for behavior on other types.

Usage: containsfield=InnerStructField.Field

Field Excludes Another Field's Value

This validates that the current field's string value does not contain the string value of the field named by the parameter. It should only be used with string types. If the referenced field cannot be resolved, validation succeeds. See the behavior of reflect.Value.String() for behavior on other types.

Usage: fieldexcludes=InnerStructField.Field

Unique

For arrays & slices, unique will ensure that there are no duplicates. For maps, unique will ensure that there are no duplicate values. For slices of struct, unique will ensure that there are no duplicate values in a field of the struct specified via a parameter.

// For arrays, slices, and maps:
Usage: unique

// For slices of struct:
Usage: unique=field

ValidateFn

This validates that an object responds to a method that can return error or bool. By default it expects an interface Validate() error and check that the method does not return an error. Other methods can be specified using two signatures: If the method returns an error, it check if the return value is nil. If the method returns a boolean, it checks if the value is true.

// to use the default method Validate() error
Usage: validateFn

// to use the custom method IsValid() bool (or error)
Usage: validateFn=IsValid

Alpha Only

This validates that a string value contains ASCII alpha characters only

Usage: alpha

Alpha Space

This validates that a string value contains ASCII alpha characters and spaces only

Usage: alphaspace

Alphanumeric

This validates that a string value contains ASCII alphanumeric characters only

Usage: alphanum

Alphanumeric Space

This validates that a string value contains ASCII alphanumeric characters and spaces only

Usage: alphanumspace

Alpha Unicode

This validates that a string value contains unicode alpha characters only

Usage: alphaunicode

Alphanumeric Unicode

This validates that a string value contains unicode alphanumeric characters only

Usage: alphanumunicode

Boolean

This validates that a string value can successfully be parsed into a boolean with strconv.ParseBool

Usage: boolean

Number

This validates that a string value contains number values only. For integers or float it returns true.

Usage: number

Numeric

This validates that a string value contains a basic numeric value. basic excludes exponents etc... for integers or float it returns true.

Usage: numeric

Hexadecimal String

This validates that a string value contains a valid hexadecimal.

Usage: hexadecimal

Hexcolor String

This validates that a string value contains a valid hex color including hashtag (#)

Usage: hexcolor

Lowercase String

This validates that a string value contains only lowercase characters. An empty string is not a valid lowercase string.

Usage: lowercase

Uppercase String

This validates that a string value contains only uppercase characters. An empty string is not a valid uppercase string.

Usage: uppercase

RGB String

This validates that a string value contains a valid rgb color

Usage: rgb

RGBA String

This validates that a string value contains a valid rgba color

Usage: rgba

HSL String

This validates that a string value contains a valid hsl color

Usage: hsl

HSLA String

This validates that a string value contains a valid hsla color

Usage: hsla

CMYK String

This validates that a string value contains a valid cmyk color

Usage: cmyk

E.164 Phone Number String

This validates that a string value contains a valid E.164 Phone number https://en.wikipedia.org/wiki/E.164 (ex. +1123456789)

Usage: e164

E-mail String

This validates that a string value contains a valid email This may not conform to all possibilities of any rfc standard, but neither does any email provider accept all possibilities.

Usage: email

JSON String

This validates that a string value is valid JSON

Usage: json

JWT String

This validates that a string value is a valid JWT

Usage: jwt

File

This validates that a string value contains a valid file path and that the file exists on the machine. This is done using os.Stat, which is a platform independent function.

Usage: file

Image path

This validates that a string value contains a valid file path and that the file exists on the machine and is an image. This is done using os.Stat and github.com/gabriel-vasile/mimetype

Usage: image

MIME type path

This validates that a string value contains a valid file path and that the file exists on the machine and matches the provided MIME type in the form type/subtype or type/*. This is done using os.Stat and github.com/gabriel-vasile/mimetype

Usage: mimetype=image/png
Usage: mimetype=image/*

File Path

This validates that a string value contains a valid file path but does not validate the existence of that file. This is done using os.Stat, which is a platform independent function.

Usage: filepath

URL String

This validates that a string value contains a valid url This will accept any url the golang request uri accepts but must contain a schema for example http:// or rtmp://

Usage: url

URI String

This validates that a string value contains a valid uri This will accept any uri the golang request uri accepts

Usage: uri

Urn RFC 8141 String

This validataes that a string value contains a valid URN according to the RFC 8141 spec.

Usage: urn_rfc8141

Urn RFC 2141 String

This validates that a string value contains a valid URN according to the RFC 2141 spec.

Usage: urn_rfc2141

Base32 String

This validates that a string value contains a valid bas324 value. Although an empty string is valid base32 this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag.

Usage: base32

Base64 String

This validates that a string value contains a valid base64 value. Although an empty string is valid base64 this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag.

Usage: base64

Base64URL String

This validates that a string value contains a valid base64 URL safe value according the RFC4648 spec. Although an empty string is a valid base64 URL safe value, this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag.

Usage: base64url

Base64RawURL String

This validates that a string value contains a valid base64 URL safe value, but without = padding, according the RFC4648 spec, section 3.2. Although an empty string is a valid base64 URL safe value, this will report an empty string as an error, if you wish to accept an empty string as valid you can use this with the omitempty tag.

Usage: base64rawurl

Bitcoin Address

This validates that a string value contains a valid bitcoin address. The format of the string is checked to ensure it matches one of the three formats P2PKH, P2SH and performs checksum validation.

Usage: btc_addr

Bitcoin Bech32 Address (segwit)

This validates that a string value contains a valid bitcoin Bech32 address as defined by bip-0173 (https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki) Special thanks to Pieter Wuille for providing reference implementations.

Usage: btc_addr_bech32

Ethereum Address

This validates that a string value contains a valid ethereum address. The format of the string is checked to ensure it matches the standard Ethereum address format.

Usage: eth_addr

Contains

This validates that a string value contains the substring value.

Usage: contains=@

Contains Any

This validates that a string value contains any Unicode code points in the substring value.

Usage: containsany=!@#?

Contains Rune

This validates that a string value contains the supplied rune value.

Usage: containsrune=@

Excludes

This validates that a string value does not contain the substring value.

Usage: excludes=@

Excludes All

This validates that a string value does not contain any Unicode code points in the substring value.

Usage: excludesall=!@#?

Excludes Rune

This validates that a string value does not contain the supplied rune value.

Usage: excludesrune=@

Starts With

This validates that a string value starts with the supplied string value

Usage: startswith=hello

Ends With

This validates that a string value ends with the supplied string value

Usage: endswith=goodbye

Does Not Start With

This validates that a string value does not start with the supplied string value

Usage: startsnotwith=hello

Does Not End With

This validates that a string value does not end with the supplied string value

Usage: endsnotwith=goodbye

International Standard Book Number

This validates that a string value contains a valid isbn10 or isbn13 value.

Usage: isbn

International Standard Book Number 10

This validates that a string value contains a valid isbn10 value.

Usage: isbn10

International Standard Book Number 13

This validates that a string value contains a valid isbn13 value.

Usage: isbn13

Universally Unique Identifier UUID

This validates that a string value contains a valid UUID. Uppercase UUID values will not pass - use uuid_rfc4122 instead.

Usage: uuid

Universally Unique Identifier UUID v3

This validates that a string value contains a valid version 3 UUID. Uppercase UUID values will not pass - use uuid3_rfc4122 instead.

Usage: uuid3

Universally Unique Identifier UUID v4

This validates that a string value contains a valid version 4 UUID. Uppercase UUID values will not pass - use uuid4_rfc4122 instead.

Usage: uuid4

Universally Unique Identifier UUID v5

This validates that a string value contains a valid version 5 UUID. Uppercase UUID values will not pass - use uuid5_rfc4122 instead.

Usage: uuid5

Universally Unique Lexicographically Sortable Identifier ULID

This validates that a string value contains a valid ULID value.

Usage: ulid

ASCII

This validates that a string value contains only ASCII characters. NOTE: if the string is blank, this validates as true.

Usage: ascii

Printable ASCII

This validates that a string value contains only printable ASCII characters. NOTE: if the string is blank, this validates as true.

Usage: printascii

Multi-Byte Characters

This validates that a string value contains one or more multibyte characters. NOTE: if the string is blank, this validates as true.

Usage: multibyte

Data URL

This validates that a string value contains a valid DataURI. NOTE: this will also validate that the data portion is valid base64

Usage: datauri

Latitude

This validates that a string value contains a valid latitude.

Usage: latitude

Longitude

This validates that a string value contains a valid longitude.

Usage: longitude

Employer Identification Number EIN

This validates that a string value contains a valid U.S. Employer Identification Number.

Usage: ein

This validates that a string value contains a valid U.S. Social Security Number.

Usage: ssn

Internet Protocol Address IP

This validates that a string value contains a valid IP Address.

Usage: ip

Internet Protocol Address IPv4

This validates that a string value contains a valid v4 IP Address.

Usage: ipv4

Internet Protocol Address IPv6

This validates that a string value contains a valid v6 IP Address.

Usage: ipv6

Classless Inter-Domain Routing CIDR

This validates that a string value contains a valid CIDR Address.

Usage: cidr

Classless Inter-Domain Routing CIDRv4

This validates that a string value contains a valid v4 CIDR Address.

Usage: cidrv4

Classless Inter-Domain Routing CIDRv6

This validates that a string value contains a valid v6 CIDR Address.

Usage: cidrv6

Transmission Control Protocol Address TCP

This validates that a string value contains a valid resolvable TCP Address.

Usage: tcp_addr

Transmission Control Protocol Address TCPv4

This validates that a string value contains a valid resolvable v4 TCP Address.

Usage: tcp4_addr

Transmission Control Protocol Address TCPv6

This validates that a string value contains a valid resolvable v6 TCP Address.

Usage: tcp6_addr

User Datagram Protocol Address UDP

This validates that a string value contains a valid resolvable UDP Address.

Usage: udp_addr

User Datagram Protocol Address UDPv4

This validates that a string value contains a valid resolvable v4 UDP Address.

Usage: udp4_addr

User Datagram Protocol Address UDPv6

This validates that a string value contains a valid resolvable v6 UDP Address.

Usage: udp6_addr

Internet Protocol Address IP

This validates that a string value contains a valid resolvable IP Address.

Usage: ip_addr

Internet Protocol Address IPv4

This validates that a string value contains a valid resolvable v4 IP Address.

Usage: ip4_addr

Internet Protocol Address IPv6

This validates that a string value contains a valid resolvable v6 IP Address.

Usage: ip6_addr

Unix domain socket end point Address

This validates that a string value contains a valid Unix Address.

Usage: unix_addr

Unix Domain Socket Exists

This validates that a Unix domain socket file exists at the specified path. It checks both filesystem-based sockets and Linux abstract sockets (prefixed with @). For filesystem sockets, it verifies the path exists and is a socket file. For abstract sockets on Linux, it checks /proc/net/unix.

Usage: uds_exists

Media Access Control Address MAC

This validates that a string value contains a valid MAC Address.

Usage: mac

Note: See Go's ParseMAC for accepted formats and types:

http://golang.org/src/net/mac.go?s=866:918#L29

Hostname RFC 952

This validates that a string value is a valid Hostname according to RFC 952 https://tools.ietf.org/html/rfc952

Usage: hostname

Hostname RFC 1123

This validates that a string value is a valid Hostname according to RFC 1123 https://tools.ietf.org/html/rfc1123

Usage: hostname_rfc1123 or if you want to continue to use 'hostname' in your tags, create an alias.

Full Qualified Domain Name (FQDN)

This validates that a string value contains a valid FQDN.

Usage: fqdn

HTML Tags

This validates that a string value appears to be an HTML element tag including those described at https://developer.mozilla.org/en-US/docs/Web/HTML/Element

Usage: html

HTML Encoded

This validates that a string value is a proper character reference in decimal or hexadecimal format

Usage: html_encoded

URL Encoded

This validates that a string value is percent-encoded (URL encoded) according to https://tools.ietf.org/html/rfc3986#section-2.1

Usage: url_encoded

Directory Path

This validates that a string value contains a valid directory but does not validate the existence of that directory. This is done using os.Stat, which is a platform independent function. It is safest to suffix the string with os.PathSeparator if the directory may not exist at the time of validation.

Usage: dirpath

HostPort

This validates that a string value contains a valid DNS hostname and port that can be used to validate fields typically passed to sockets and connections.

Usage: hostname_port

Port

This validates that the value falls within the valid port number range of 1 to 65,535.

Usage: port

Datetime

This validates that a string value is a valid datetime based on the supplied datetime format. Supplied format must match the official Go time format layout as documented in https://golang.org/pkg/time/

Usage: datetime=2006-01-02

Iso3166-1 alpha-2

This validates that a string value is a valid country code based on iso3166-1 alpha-2 standard. see: https://www.iso.org/iso-3166-country-codes.html

Usage: iso3166_1_alpha2

Iso3166-1 alpha-3

This validates that a string value is a valid country code based on iso3166-1 alpha-3 standard. see: https://www.iso.org/iso-3166-country-codes.html

Usage: iso3166_1_alpha3

Iso3166-1 alpha-numeric

This validates that a string value is a valid country code based on iso3166-1 alpha-numeric standard. see: https://www.iso.org/iso-3166-country-codes.html

Usage: iso3166_1_alpha3

BCP 47 Language Tag

This validates that a string value is a valid BCP 47 language tag, as parsed by language.Parse. More information on https://pkg.go.dev/golang.org/x/text/language

Usage: bcp47_language_tag

BCP 47 Strict Language Tag

This validates that a string value is a valid BCP 47 language tag strictly following RFC 5646 rules, unlike language.Parse which also accepts Unicode extensions. see https://www.rfc-editor.org/rfc/bcp/bcp47.txt

Usage: bcp47_strict_language_tag

BIC (SWIFT code - 2022 standard)

This validates that a string value is a valid Business Identifier Code (SWIFT code), defined in ISO 9362:2022. More information on https://www.iso.org/standard/84108.html

Usage: bic

BIC (SWIFT code - 2014 standard)

This validates that a string value is a valid Business Identifier Code (SWIFT code), defined in ISO 9362:2014. More information on https://www.iso.org/standard/60390.html

Usage: bic_iso_9362_2014

RFC 1035 label

This validates that a string value is a valid dns RFC 1035 label, defined in RFC 1035. More information on https://datatracker.ietf.org/doc/html/rfc1035

Usage: dns_rfc1035_label

TimeZone

This validates that a string value is a valid time zone based on the time zone database present on the system. Although empty value and Local value are allowed by time.LoadLocation golang function, they are not allowed by this validator. More information on https://golang.org/pkg/time/#LoadLocation

Usage: timezone

Semantic Version

This validates that a string value is a valid semver version, defined in Semantic Versioning 2.0.0. More information on https://semver.org/

Usage: semver

CVE Identifier

This validates that a string value is a valid cve id, defined in cve mitre. More information on https://cve.mitre.org/

Usage: cve

Credit Card

This validates that a string value contains a valid credit card number using Luhn algorithm.

Usage: credit_card

Luhn Checksum

Usage: luhn_checksum

This validates that a string or (u)int value contains a valid checksum using the Luhn algorithm.

MongoDB

This validates that a string is a valid 24 character hexadecimal string or valid connection string.

Usage: mongodb
       mongodb_connection_string

Example:

type Test struct {
	ObjectIdField         string `validate:"mongodb"`
	ConnectionStringField string `validate:"mongodb_connection_string"`
}

Cron

This validates that a string value contains a valid cron expression.

Usage: cron

SpiceDb ObjectID/Permission/Object Type

This validates that a string is valid for use with SpiceDb for the indicated purpose. If no purpose is given, a purpose of 'id' is assumed.

Usage: spicedb=id|permission|type

Alias Validators and Tags

Alias Validators and Tags NOTE: When returning an error, the tag returned in "FieldError" will be the alias tag unless the dive tag is part of the alias. Everything after the dive tag is not reported as the alias tag. Also, the "ActualTag" in the before case will be the actual tag within the alias that failed.

Here is a list of the current built in alias tags:

"iscolor"
	alias is "hexcolor|rgb|rgba|hsl|hsla" (Usage: iscolor)
"country_code"
	alias is "iso3166_1_alpha2|iso3166_1_alpha3|iso3166_1_alpha_numeric" (Usage: country_code)

Validator notes:

regex
	a regex validator won't be added because commas and = signs can be part
	of a regex which conflict with the validation definitions. Although
	workarounds can be made, they take away from using pure regex's.
	Furthermore it's quick and dirty but the regex's become harder to
	maintain and are not reusable, so it's as much a programming philosophy
	as anything.

	In place of this new validator functions should be created; a regex can
	be used within the validator function and even be precompiled for better
	efficiency within regexes.go.

	And the best reason, you can submit a pull request and we can keep on
	adding to the validation library of this package!

Non standard validators

A collection of validation rules that are frequently needed but are more complex than the ones found in the baked in validators. A non standard validator must be registered manually like you would with your own custom validation functions.

Example of registration and use:

type Test struct {
	TestField string `validate:"yourtag"`
}

t := &Test{
	TestField: "Test"
}

validate := validator.New()
validate.RegisterValidation("yourtag", validators.NotBlank)

Here is a list of the current non standard validators:

NotBlank
	This validates that the value is not blank or with length zero.
	For strings ensures they do not contain only spaces. For channels, maps, slices and arrays
	ensures they don't have zero length. For others, a non empty value is required.

	Usage: notblank

Panics

This package panics when bad input is provided, this is by design, bad code like that should not make it to production.

type Test struct {
	TestField string `validate:"nonexistentfunction=1"`
}

t := &Test{
	TestField: "Test"
}

validate.Struct(t) // this will panic

Functions

func New(options ...Option) *Validate

New returns a new instance of 'validate' with sane defaults. Validate is designed to be thread-safe and used as a singleton instance. It caches information about your struct and validations, in essence only parsing your validation tags once per struct type. Using multiple instances neglects the benefit of caching.

func WithPrivateFieldValidation() Option

WithPrivateFieldValidation activates validation for unexported fields via the use of the unsafe package.

By opting into this feature you are acknowledging that you are aware of the risks and accept any current or future consequences of using this feature.

func WithRequiredStructEnabled() Option

WithRequiredStructEnabled enables required tag on non-pointer structs to be applied instead of ignored.

This was made opt-in behaviour in order to maintain backward compatibility with the behaviour previous to being able to apply struct level validations on struct fields directly.

It is recommended you enabled this as it will be the default behaviour in v11+

func WithTagNameFuncBlankOmit() Option

WithTagNameFuncBlankOmit makes a blank return from a RegisterTagNameFunc omit the field from the error namespace instead of silently falling back to the struct field name.

This was made opt-in behaviour to maintain backward compatibility with existing callers that rely on the fallback for error namespaces.

It is recommended you enable this as it will be the default behaviour in v11+.

Types

type CustomTypeFunc

CustomTypeFunc allows for overriding or adding custom field type handler functions field = field value of the type to return a value to be validated example Valuer from sql driver see https://golang.org/src/database/sql/driver/types.go?s=1210:1293#L29

type CustomTypeFunc func(field reflect.Value) interface{}

type FieldError

FieldError contains all functions to get error details

type FieldError interface {

	// Tag returns the validation tag that failed. if the
	// validation was an alias, this will return the
	// alias name and not the underlying tag that failed.
	//
	// eg. alias "iscolor": "hexcolor|rgb|rgba|hsl|hsla"
	// will return "iscolor"
	Tag() string

	// ActualTag returns the validation tag that failed, even if an
	// alias the actual tag within the alias will be returned.
	// If an 'or' validation fails the entire or will be returned.
	//
	// eg. alias "iscolor": "hexcolor|rgb|rgba|hsl|hsla"
	// will return "hexcolor|rgb|rgba|hsl|hsla"
	ActualTag() string

	// Namespace returns the namespace for the field error, with the tag
	// name taking precedence over the field's actual name.
	//
	// eg. JSON name "User.fname"
	//
	// See StructNamespace() for a version that returns actual names.
	//
	// NOTE: this field can be blank when validating a single primitive field
	// using validate.Field(...) as there is no way to extract it's name
	Namespace() string

	// StructNamespace returns the namespace for the field error, with the field's
	// actual name.
	//
	// eg. "User.FirstName" see Namespace for comparison
	//
	// NOTE: this field can be blank when validating a single primitive field
	// using validate.Field(...) as there is no way to extract its name
	StructNamespace() string

	// Field returns the field's name with the tag name taking precedence over the
	// field's actual name.
	//
	// `RegisterTagNameFunc` must be registered to get tag value.
	//
	// eg. JSON name "fname"
	// see StructField for comparison
	Field() string

	// StructField returns the field's actual name from the struct, when able to determine.
	//
	// eg.  "FirstName"
	// see Field for comparison
	StructField() string

	// Value returns the actual field's value in case needed for creating the error
	// message
	Value() interface{}

	// Param returns the param value, in string form for comparison; this will also
	// help with generating an error message
	Param() string

	// Kind returns the Field's reflect Kind
	//
	// eg. time.Time's kind is a struct
	Kind() reflect.Kind

	// Type returns the Field's reflect Type
	//
	// eg. time.Time's type is time.Time
	Type() reflect.Type

	// Translate returns the FieldError's translated error
	// from the provided 'ut.Translator' and registered 'TranslationFunc'
	//
	// NOTE: if no registered translator can be found it returns the same as
	// calling fe.Error()
	Translate(ut ut.Translator) string

	// Error returns the FieldError's message
	Error() string
}

Methods

Tag func() string
Tag returns the validation tag that failed. if the validation was an alias, this will return the alias name and not the underlying tag that failed.

eg. alias "iscolor": "hexcolor|rgb|rgba|hsl|hsla" will return "iscolor"
ActualTag func() string
ActualTag returns the validation tag that failed, even if an alias the actual tag within the alias will be returned. If an 'or' validation fails the entire or will be returned.

eg. alias "iscolor": "hexcolor|rgb|rgba|hsl|hsla" will return "hexcolor|rgb|rgba|hsl|hsla"
Namespace func() string
Namespace returns the namespace for the field error, with the tag name taking precedence over the field's actual name.

eg. JSON name "User.fname"

See StructNamespace() for a version that returns actual names.

NOTE: this field can be blank when validating a single primitive field using validate.Field(...) as there is no way to extract it's name
StructNamespace func() string
StructNamespace returns the namespace for the field error, with the field's actual name.

eg. "User.FirstName" see Namespace for comparison

NOTE: this field can be blank when validating a single primitive field using validate.Field(...) as there is no way to extract its name
Field func() string
Field returns the field's name with the tag name taking precedence over the field's actual name.

RegisterTagNameFunc must be registered to get tag value.

eg. JSON name "fname" see StructField for comparison
StructField func() string
StructField returns the field's actual name from the struct, when able to determine.

eg. "FirstName" see Field for comparison
Value func() interface{}
Value returns the actual field's value in case needed for creating the error message
Param func() string
Param returns the param value, in string form for comparison; this will also help with generating an error message
Kind func() reflect.Kind
Kind returns the Field's reflect Kind

eg. time.Time's kind is a struct
Type func() reflect.Type
Type returns the Field's reflect Type

eg. time.Time's type is time.Time
Translate func(ut ut.Translator) string
Translate returns the FieldError's translated error from the provided 'ut.Translator' and registered 'TranslationFunc'

NOTE: if no registered translator can be found it returns the same as calling fe.Error()
Error func() string
Error returns the FieldError's message

type FieldLevel

FieldLevel contains all the information and helper functions to validate a field

type FieldLevel interface {

	// Top returns the top level struct, if any
	Top() reflect.Value

	// Parent returns the current fields parent struct, if any or
	// the comparison value if called 'VarWithValue'
	Parent() reflect.Value

	// Field returns current field for validation
	Field() reflect.Value

	// FieldName returns the field's name with the tag
	// name taking precedence over the fields actual name.
	FieldName() string

	// StructFieldName returns the struct field's name
	StructFieldName() string

	// Param returns param for validation against current field
	Param() string

	// GetTag returns the current validations tag name
	GetTag() string

	// ExtractType gets the actual underlying type of field value.
	// It will dive into pointers, customTypes and return you the
	// underlying value and it's kind.
	ExtractType(field reflect.Value) (value reflect.Value, kind reflect.Kind, nullable bool)

	// GetStructFieldOK traverses the parent struct to retrieve a specific field denoted by the provided namespace
	// in the param and returns the field, field kind and whether is was successful in retrieving
	// the field at all.
	//
	// NOTE: when not successful ok will be false, this can happen when a nested struct is nil and so the field
	// could not be retrieved because it didn't exist.
	//
	// Deprecated: Use GetStructFieldOK2() instead which also return if the value is nullable.
	GetStructFieldOK() (reflect.Value, reflect.Kind, bool)

	// GetStructFieldOKAdvanced is the same as GetStructFieldOK except that it accepts the parent struct to start looking for
	// the field and namespace allowing more extensibility for validators.
	//
	// Deprecated: Use GetStructFieldOKAdvanced2() instead which also return if the value is nullable.
	GetStructFieldOKAdvanced(val reflect.Value, namespace string) (reflect.Value, reflect.Kind, bool)

	// GetStructFieldOK2 traverses the parent struct to retrieve a specific field denoted by the provided namespace
	// in the param and returns the field, field kind, if it's a nullable type and whether is was successful in retrieving
	// the field at all.
	//
	// NOTE: when not successful ok will be false, this can happen when a nested struct is nil and so the field
	// could not be retrieved because it didn't exist.
	GetStructFieldOK2() (reflect.Value, reflect.Kind, bool, bool)

	// GetStructFieldOKAdvanced2 is the same as GetStructFieldOK except that it accepts the parent struct to start looking for
	// the field and namespace allowing more extensibility for validators.
	GetStructFieldOKAdvanced2(val reflect.Value, namespace string) (reflect.Value, reflect.Kind, bool, bool)
}

Methods

Top func() reflect.Value
Top returns the top level struct, if any
Parent func() reflect.Value
Parent returns the current fields parent struct, if any or the comparison value if called 'VarWithValue'
Field func() reflect.Value
Field returns current field for validation
FieldName func() string
FieldName returns the field's name with the tag name taking precedence over the fields actual name.
StructFieldName func() string
StructFieldName returns the struct field's name
Param func() string
Param returns param for validation against current field
GetTag func() string
GetTag returns the current validations tag name
ExtractType func(field reflect.Value) (value reflect.Value, kind reflect.Kind, nullable bool)
ExtractType gets the actual underlying type of field value. It will dive into pointers, customTypes and return you the underlying value and it's kind.
GetStructFieldOK func() (reflect.Value, reflect.Kind, bool)
GetStructFieldOK traverses the parent struct to retrieve a specific field denoted by the provided namespace in the param and returns the field, field kind and whether is was successful in retrieving the field at all.

NOTE: when not successful ok will be false, this can happen when a nested struct is nil and so the field could not be retrieved because it didn't exist.

Deprecated: Use GetStructFieldOK2() instead which also return if the value is nullable.
GetStructFieldOKAdvanced func(val reflect.Value, namespace string) (reflect.Value, reflect.Kind, bool)
GetStructFieldOKAdvanced is the same as GetStructFieldOK except that it accepts the parent struct to start looking for the field and namespace allowing more extensibility for validators.

Deprecated: Use GetStructFieldOKAdvanced2() instead which also return if the value is nullable.
GetStructFieldOK2 func() (reflect.Value, reflect.Kind, bool, bool)
GetStructFieldOK2 traverses the parent struct to retrieve a specific field denoted by the provided namespace in the param and returns the field, field kind, if it's a nullable type and whether is was successful in retrieving the field at all.

NOTE: when not successful ok will be false, this can happen when a nested struct is nil and so the field could not be retrieved because it didn't exist.
GetStructFieldOKAdvanced2 func(val reflect.Value, namespace string) (reflect.Value, reflect.Kind, bool, bool)
GetStructFieldOKAdvanced2 is the same as GetStructFieldOK except that it accepts the parent struct to start looking for the field and namespace allowing more extensibility for validators.

type FilterFunc

FilterFunc is the type used to filter fields using StructFiltered(...) function. returning true results in the field being filtered/skipped from validation

type FilterFunc func(ns []byte) bool

type Func

Func accepts a FieldLevel interface for all validation needs. The return value should be true when validation succeeds.

type Func func(fl FieldLevel) bool

type FuncCtx

FuncCtx accepts a context.Context and FieldLevel interface for all validation needs. The return value should be true when validation succeeds.

type FuncCtx func(ctx context.Context, fl FieldLevel) bool

type InvalidValidationError

InvalidValidationError describes an invalid argument passed to Struct, StructExcept, StructPartialorField`

type InvalidValidationError struct {
	Type reflect.Type
}

Fields

Type reflect.Type

func Error) Error() string

Error returns InvalidValidationError message

type Option

Option represents a configurations option to be applied to validator during initialization.

type Option func(*Validate)

type RegisterTranslationsFunc

RegisterTranslationsFunc allows for registering of translations for a 'ut.Translator' for use within the 'TranslationFunc'

type RegisterTranslationsFunc func(ut ut.Translator) error

type StructLevel

StructLevel contains all the information and helper functions to validate a struct

type StructLevel interface {

	// Validator returns the main validation object, in case one wants to call validations internally.
	// this is so you don't have to use anonymous functions to get access to the validate
	// instance.
	Validator() *Validate

	// Top returns the top level struct, if any
	Top() reflect.Value

	// Parent returns the current fields parent struct, if any
	Parent() reflect.Value

	// Current returns the current struct.
	Current() reflect.Value

	// ExtractType gets the actual underlying type of field value.
	// It will dive into pointers, customTypes and return you the
	// underlying value and its kind.
	ExtractType(field reflect.Value) (value reflect.Value, kind reflect.Kind, nullable bool)

	// ReportError reports an error just by passing the field and tag information
	//
	// NOTES:
	//
	// fieldName and structFieldName get appended to the existing
	// namespace that validator is on. e.g. pass 'FirstName' or
	// 'Names[0]' depending on the nesting
	//
	// tag can be an existing validation tag or just something you make up
	// and process on the flip side it's up to you.
	ReportError(field interface{}, fieldName, structFieldName string, tag, param string)

	// ReportValidationErrors reports an error just by passing ValidationErrors
	//
	// NOTES:
	//
	// relativeNamespace and relativeActualNamespace get appended to the
	// existing namespace that validator is on.
	// e.g. pass 'User.FirstName' or 'Users[0].FirstName' depending
	// on the nesting. most of the time they will be blank, unless you validate
	// at a level lower the current field depth
	ReportValidationErrors(relativeNamespace, relativeActualNamespace string, errs ValidationErrors)
}

Methods

Validator func() *Validate
Validator returns the main validation object, in case one wants to call validations internally. this is so you don't have to use anonymous functions to get access to the validate instance.
Top func() reflect.Value
Top returns the top level struct, if any
Parent func() reflect.Value
Parent returns the current fields parent struct, if any
Current func() reflect.Value
Current returns the current struct.
ExtractType func(field reflect.Value) (value reflect.Value, kind reflect.Kind, nullable bool)
ExtractType gets the actual underlying type of field value. It will dive into pointers, customTypes and return you the underlying value and its kind.
ReportError func(field interface{}, fieldName, structFieldName string, tag, param string)
ReportError reports an error just by passing the field and tag information

NOTES:

fieldName and structFieldName get appended to the existing namespace that validator is on. e.g. pass 'FirstName' or 'Names[0]' depending on the nesting

tag can be an existing validation tag or just something you make up and process on the flip side it's up to you.
ReportValidationErrors func(relativeNamespace, relativeActualNamespace string, errs ValidationErrors)
ReportValidationErrors reports an error just by passing ValidationErrors

NOTES:

relativeNamespace and relativeActualNamespace get appended to the existing namespace that validator is on. e.g. pass 'User.FirstName' or 'Users[0].FirstName' depending on the nesting. most of the time they will be blank, unless you validate at a level lower the current field depth

type StructLevelFunc

StructLevelFunc accepts all values needed for struct level validation

type StructLevelFunc func(sl StructLevel)

type StructLevelFuncCtx

StructLevelFuncCtx accepts all values needed for struct level validation but also allows passing of contextual validation information via context.Context.

type StructLevelFuncCtx func(ctx context.Context, sl StructLevel)

type TagNameFunc

TagNameFunc allows for adding of a custom tag name parser

type TagNameFunc func(field reflect.StructField) string

type TranslationFunc

TranslationFunc is the function type used to register or override custom translations

type TranslationFunc func(ut ut.Translator, fe FieldError) string

type Validate

Validate contains the validator settings and cache

type Validate struct {
	// contains filtered or unexported fields
}

func RegisterAlias(alias, tags string)

RegisterAlias registers a mapping of a single validation tag that defines a common or complex set of validation(s) to simplify adding validation to structs.

NOTE: this function is not thread-safe it is intended that these all be registered prior to any validation

func RegisterCustomTypeFunc(fn CustomTypeFunc, types ...interface{})

RegisterCustomTypeFunc registers a CustomTypeFunc against a number of types

NOTE: this method is not thread-safe it is intended that these all be registered prior to any validation

func RegisterStructValidation(fn StructLevelFunc, types ...interface{})

RegisterStructValidation registers a StructLevelFunc against a number of types.

NOTE:

this method is not thread-safe it is intended that these all be registered prior to any validation

func RegisterStructValidationCtx(fn StructLevelFuncCtx, types ...interface{})

RegisterStructValidationCtx registers a StructLevelFuncCtx against a number of types and allows passing of contextual validation information via context.Context.

NOTE:

this method is not thread-safe it is intended that these all be registered prior to any validation

func RegisterStructValidationMapRules(rules map[string]string, types ...interface{})

RegisterStructValidationMapRules registers validate map rules. Be aware that map validation rules supersede those defined on a/the struct if present.

NOTE: this method is not thread-safe it is intended that these all be registered prior to any validation

func RegisterTagNameFunc(fn TagNameFunc)

RegisterTagNameFunc registers a function to get alternate names for StructFields.

eg. to use the names which have been specified for JSON representations of structs, rather than normal Go field names:

validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
    name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
    // skip if tag key says it should be ignored
    if name == "-" {
        return ""
    }
    return name
})

func RegisterTranslation(tag string, trans ut.Translator, registerFn RegisterTranslationsFunc, translationFn TranslationFunc) (err error)

RegisterTranslation registers translations against the provided tag.

func RegisterValidation(tag string, fn Func, callValidationEvenIfNull ...bool) error

RegisterValidation adds a validation with the given tag

NOTES:

if the key already exists, the previous validation function will be replaced.
this method is not thread-safe it is intended that these all be registered prior to any validation

func RegisterValidationCtx(tag string, fn FuncCtx, callValidationEvenIfNull ...bool) error

RegisterValidationCtx does the same as RegisterValidation on accepts a FuncCtx validation allowing context.Context validation support.

func SetTagName(name string)

SetTagName allows for changing of the default tag name of 'validate'

func Struct(s interface{}) error

Struct validates a structs exposed fields, and automatically validates nested structs, unless otherwise specified.

It returns InvalidValidationError for bad values passed in and nil or ValidationErrors as error otherwise. You will need to assert the error if it's not nil eg. err.(validator.ValidationErrors) to access the array of errors.

func StructCtx(ctx context.Context, s interface{}) (err error)

StructCtx validates a structs exposed fields, and automatically validates nested structs, unless otherwise specified and also allows passing of context.Context for contextual validation information.

func StructExcept(s interface{}, fields ...string) error

StructExcept validates all fields except the ones passed in. Fields may be provided in a namespaced fashion relative to the struct provided i.e. NestedStruct.Field or NestedArrayField[0].Struct.Name

func StructExceptCtx(ctx context.Context, s interface{}, fields ...string) (err error)

StructExceptCtx validates all fields except the ones passed in and allows passing of contextual validation information via context.Context Fields may be provided in a namespaced fashion relative to the struct provided i.e. NestedStruct.Field or NestedArrayField[0].Struct.Name

func StructFiltered(s interface{}, fn FilterFunc) error

StructFiltered validates a structs exposed fields, that pass the FilterFunc check and automatically validates nested structs, unless otherwise specified.

func StructFilteredCtx(ctx context.Context, s interface{}, fn FilterFunc) (err error)

StructFilteredCtx validates a structs exposed fields, that pass the FilterFunc check and automatically validates nested structs, unless otherwise specified and also allows passing of contextual validation information via context.Context

func StructPartial(s interface{}, fields ...string) error

StructPartial validates the fields passed in only, ignoring all others. Fields may be provided in a namespaced fashion relative to the struct provided eg. NestedStruct.Field or NestedArrayField[0].Struct.Name

func StructPartialCtx(ctx context.Context, s interface{}, fields ...string) (err error)

StructPartialCtx validates the fields passed in only, ignoring all others and allows passing of contextual validation information via context.Context Fields may be provided in a namespaced fashion relative to the struct provided eg. NestedStruct.Field or NestedArrayField[0].Struct.Name

func ValidateMap(data map[string]interface{}, rules map[string]interface{}) map[string]interface{}

ValidateMap validates map data from a map of tags

func ValidateMapCtx(ctx context.Context, data map[string]interface{}, rules map[string]interface{}) map[string]interface{}

ValidateMapCtx validates a map using a map of validation rules and allows passing of contextual validation information via context.Context.

func Var(field interface{}, tag string) error

Var validates a single variable using tag style validation. eg. var i int validate.Var(i, "gt=1,lt=10")

WARNING: a struct can be passed for validation eg. time.Time is a struct or if you have a custom type and have registered a custom type handler, so must allow it; however unforeseen validations will occur if trying to validate a struct that is meant to be passed to 'validate.Struct'

func VarCtx(ctx context.Context, field interface{}, tag string) (err error)

VarCtx validates a single variable using tag style validation and allows passing of contextual validation information via context.Context. eg. var i int validate.Var(i, "gt=1,lt=10")

func VarWithKey(key string, field interface{}, tag string) error

VarWithKey validates a single variable with a key to be included in the returned error using tag style validation eg. var s string validate.VarWithKey("email_address", s, "required,email")

func VarWithKeyCtx(ctx context.Context, key string, field interface{}, tag string) (err error)

VarWithKeyCtx validates a single variable with a key to be included in the returned error using tag style validation and allows passing of contextual validation information via context.Context. eg. var s string validate.VarWithKeyCtx("email_address", s, "required,email")

func VarWithValue(field interface{}, other interface{}, tag string) error

VarWithValue validates a single variable, against another variable/field's value using tag style validation eg. s1 := "abcd" s2 := "abcd" validate.VarWithValue(s1, s2, "eqcsfield") // returns true

func VarWithValueCtx(ctx context.Context, field interface{}, other interface{}, tag string) (err error)

VarWithValueCtx validates a single variable, against another variable/field's value using tag style validation and allows passing of contextual validation information via context.Context. eg. s1 := "abcd" s2 := "abcd" validate.VarWithValue(s1, s2, "eqcsfield") // returns true

type ValidationErrors

ValidationErrors is an array of FieldError's for use in custom error messages post validation.

type ValidationErrors []FieldError

func Errors) Error() string

Error is intended for use in development + debugging and not intended to be a production error message. It allows ValidationErrors to subscribe to the Error interface. All information to create an error message specific to your application is contained within the FieldError found within the ValidationErrors array

func Translate(ut ut.Translator) ValidationErrorsTranslations

Translate translates all of the ValidationErrors

type ValidationErrorsTranslations

ValidationErrorsTranslations is the translation return type

type ValidationErrorsTranslations map[string]string

type Valuer

Valuer is an interface that allows you to expose a method on a type (including generic types) that returns a value that is supposed to be validated.

type Valuer interface {
	// ValidatorValue returns the value that is supposed to be validated.
	ValidatorValue() any
}

Methods

ValidatorValue func() any
ValidatorValue returns the value that is supposed to be validated.