go-playground/validator
:100:Go Struct and Field validation, including Cross Field, Cross Struct, Map, Slice and Array diving
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Updated 2/27/2026
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About validator
Package validator
Package validator implements value validations for structs and individual fields based on tags.
It has the following unique features:
- Cross Field and Cross Struct validations by using validation tags or custom validators.
- Slice, Array and Map diving, which allows any or all levels of a multidimensional field to be validated.
- Ability to dive into both map keys and values for validation
- Handles type interface by determining it's underlying type prior to validation.
- Handles custom field types such as sql driver Valuer see Valuer
- Alias validation tags, which allows for mapping of several validations to a single tag for easier defining of validations on structs
- Extraction of custom defined Field Name e.g. can specify to extract the JSON name while validating and have it available in the resulting FieldError
- Customizable i18n aware error messages.
- Default validator for the gin web framework; upgrading from v8 to v9 in gin see here
A Call for Maintainers
Please read the discussiong started here if you are interested in contributing/helping maintain this package.
Installation
Use go get.
go get github.com/go-playground/validator/v10
Then import the validator package into your own code.
import "github.com/go-playground/validator/v10"
Error Return Value
Validation functions return type error
They return type error to avoid the issue discussed in the following, where err is always != nil:
Validator returns 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 := validate.Struct(mystruct)
validationErrors := err.(validator.ValidationErrors)
Usage and documentation
Please see https://pkg.go.dev/github.com/go-playground/validator/v10 for detailed usage docs.
Examples:
- Simple
- Custom Field Types
- Struct Level
- Translations & Custom Errors
- Gin upgrade and/or override validator
- wash - an example application putting it all together
Baked-in Validations
Special Notes:
- If new to using validator it is highly recommended to initialize it using the
WithRequiredStructEnabledoption which is opt-in to new behaviour that will become the default behaviour in v11+. See documentation for more details.
validate := validator.New(validator.WithRequiredStructEnabled())
Fields:
| Tag | Description |
|---|---|
| eqcsfield | Field Equals Another Field (relative) |
| eqfield | Field Equals Another Field |
| fieldcontains | Check the indicated characters are present in the Field |
| fieldexcludes | Check the indicated characters are not present in the field |
| gtcsfield | Field Greater Than Another Relative Field |
| gtecsfield | Field Greater Than or Equal To Another Relative Field |
| gtefield | Field Greater Than or Equal To Another Field |
| gtfield | Field Greater Than Another Field |
| ltcsfield | Less Than Another Relative Field |
| ltecsfield | Less Than or Equal To Another Relative Field |
| ltefield | Less Than or Equal To Another Field |
| ltfield | Less Than Another Field |
| necsfield | Field Does Not Equal Another Field (relative) |
| nefield | Field Does Not Equal Another Field |
Network:
| Tag | Description |
|---|---|
| cidr | Classless Inter-Domain Routing CIDR |
| cidrv4 | Classless Inter-Domain Routing CIDRv4 |
| cidrv6 | Classless Inter-Domain Routing CIDRv6 |
| datauri | Data URL |
| fqdn | Full Qualified Domain Name (FQDN) |
| hostname | Hostname RFC 952 |
| hostname_port | HostPort |
| hostname_rfc1123 | Hostname RFC 1123 |
| ip | Internet Protocol Address IP |
| ip4_addr | Internet Protocol Address IPv4 |
| ip6_addr | Internet Protocol Address IPv6 |
| ip_addr | Internet Protocol Address IP |
| ipv4 | Internet Protocol Address IPv4 |
| ipv6 | Internet Protocol Address IPv6 |
| mac | Media Access Control Address MAC |
| tcp4_addr | Transmission Control Protocol Address TCPv4 |
| tcp6_addr | Transmission Control Protocol Address TCPv6 |
| tcp_addr | Transmission Control Protocol Address TCP |
| udp4_addr | User Datagram Protocol Address UDPv4 |
| udp6_addr | User Datagram Protocol Address UDPv6 |
| udp_addr | User Datagram Protocol Address UDP |
| unix_addr | Unix domain socket end point Address |
| uri | URI String |
| url | URL String |
| http_url | HTTP URL String |
| url_encoded | URL Encoded |
| urn_rfc2141 | Urn RFC 2141 String |
Strings:
| Tag | Description |
|---|---|
| alpha | Alpha Only |
| alphanum | Alphanumeric |
| alphanumunicode | Alphanumeric Unicode |
| alphaunicode | Alpha Unicode |
| ascii | ASCII |
| boolean | Boolean |
| contains | Contains |
| containsany | Contains Any |
| containsrune | Contains Rune |
| endsnotwith | Ends Not With |
| endswith | Ends With |
| excludes | Excludes |
| excludesall | Excludes All |
| excludesrune | Excludes Rune |
| lowercase | Lowercase |
| multibyte | Multi-Byte Characters |
| number | Number |
| numeric | Numeric |
| printascii | Printable ASCII |
| startsnotwith | Starts Not With |
| startswith | Starts With |
| uppercase | Uppercase |
Format:
| Tag | Description |
|---|---|
| base64 | Base64 String |
| base64url | Base64URL String |
| base64rawurl | Base64RawURL String |
| bic | Business Identifier Code (ISO 9362) |
| bcp47_language_tag | Language tag (BCP 47) |
| btc_addr | Bitcoin Address |
| btc_addr_bech32 | Bitcoin Bech32 Address (segwit) |
| credit_card | Credit Card Number |
| mongodb | MongoDB ObjectID |
| mongodb_connection_string | MongoDB Connection String |
| cron | Cron |
| spicedb | SpiceDb ObjectID/Permission/Type |
| datetime | Datetime |
| e164 | e164 formatted phone number |
| ein | U.S. Employeer Identification Number |
| E-mail String | |
| eth_addr | Ethereum Address |
| hexadecimal | Hexadecimal String |
| hexcolor | Hexcolor String |
| hsl | HSL String |
| hsla | HSLA String |
| html | HTML Tags |
| html_encoded | HTML Encoded |
| isbn | International Standard Book Number |
| isbn10 | International Standard Book Number 10 |
| isbn13 | International Standard Book Number 13 |
| issn | International Standard Serial Number |
| iso3166_1_alpha2 | Two-letter country code (ISO 3166-1 alpha-2) |
| iso3166_1_alpha3 | Three-letter country code (ISO 3166-1 alpha-3) |
| iso3166_1_alpha_numeric | Numeric country code (ISO 3166-1 numeric) |
| iso3166_2 | Country subdivision code (ISO 3166-2) |
| iso4217 | Currency code (ISO 4217) |
| json | JSON |
| jwt | JSON Web Token (JWT) |
| latitude | Latitude |
| longitude | Longitude |
| luhn_checksum | Luhn Algorithm Checksum (for strings and (u)int) |
| postcode_iso3166_alpha2 | Postcode |
| postcode_iso3166_alpha2_field | Postcode |
| rgb | RGB String |
| rgba | RGBA String |
| ssn | Social Security Number SSN |
| timezone | Timezone |
| uuid | Universally Unique Identifier UUID |
| uuid3 | Universally Unique Identifier UUID v3 |
| uuid3_rfc4122 | Universally Unique Identifier UUID v3 RFC4122 |
| uuid4 | Universally Unique Identifier UUID v4 |
| uuid4_rfc4122 | Universally Unique Identifier UUID v4 RFC4122 |
| uuid5 | Universally Unique Identifier UUID v5 |
| uuid5_rfc4122 | Universally Unique Identifier UUID v5 RFC4122 |
| uuid_rfc4122 | Universally Unique Identifier UUID RFC4122 |
| md4 | MD4 hash |
| md5 | MD5 hash |
| sha256 | SHA256 hash |
| sha384 | SHA384 hash |
| sha512 | SHA512 hash |
| ripemd128 | RIPEMD-128 hash |
| ripemd128 | RIPEMD-160 hash |
| tiger128 | TIGER128 hash |
| tiger160 | TIGER160 hash |
| tiger192 | TIGER192 hash |
| semver | Semantic Versioning 2.0.0 |
| ulid | Universally Unique Lexicographically Sortable Identifier ULID |
| cve | Common Vulnerabilities and Exposures Identifier (CVE id) |
Comparisons:
| Tag | Description |
|---|---|
| eq | Equals |
| eq_ignore_case | Equals ignoring case |
| gt | Greater than |
| gte | Greater than or equal |
| lt | Less Than |
| lte | Less Than or Equal |
| ne | Not Equal |
| ne_ignore_case | Not Equal ignoring case |
Other:
| Tag | Description |
|---|---|
| dir | Existing Directory |
| dirpath | Directory Path |
| file | Existing File |
| filepath | File Path |
| image | Image |
| isdefault | Is Default |
| len | Length |
| max | Maximum |
| min | Minimum |
| oneof | One Of |
| required | Required |
| required_if | Required If |
| required_unless | Required Unless |
| required_with | Required With |
| required_with_all | Required With All |
| required_without | Required Without |
| required_without_all | Required Without All |
| excluded_if | Excluded If |
| excluded_unless | Excluded Unless |
| excluded_with | Excluded With |
| excluded_with_all | Excluded With All |
| excluded_without | Excluded Without |
| excluded_without_all | Excluded Without All |
| unique | Unique |
| validateFn | Verify if the method Validate() error does not return an error (or any specified method) |
Aliases:
| Tag | Description |
|---|---|
| iscolor | hexcolor|rgb|rgba|hsl|hsla |
| country_code | iso3166_1_alpha2|iso3166_1_alpha3|iso3166_1_alpha_numeric |
Benchmarks
Run on MacBook Pro Max M3
go version go1.23.3 darwin/arm64
goos: darwin
goarch: arm64
cpu: Apple M3 Max
pkg: github.com/go-playground/validator/v10
BenchmarkFieldSuccess-16 42461943 27.88 ns/op 0 B/op 0 allocs/op
BenchmarkFieldSuccessParallel-16 486632887 2.289 ns/op 0 B/op 0 allocs/op
BenchmarkFieldFailure-16 9566167 121.3 ns/op 200 B/op 4 allocs/op
BenchmarkFieldFailureParallel-16 17551471 83.68 ns/op 200 B/op 4 allocs/op
BenchmarkFieldArrayDiveSuccess-16 7602306 155.6 ns/op 97 B/op 5 allocs/op
BenchmarkFieldArrayDiveSuccessParallel-16 20664610 59.80 ns/op 97 B/op 5 allocs/op
BenchmarkFieldArrayDiveFailure-16 4659756 252.9 ns/op 301 B/op 10 allocs/op
BenchmarkFieldArrayDiveFailureParallel-16 8010116 152.9 ns/op 301 B/op 10 allocs/op
BenchmarkFieldMapDiveSuccess-16 2834575 421.2 ns/op 288 B/op 14 allocs/op
BenchmarkFieldMapDiveSuccessParallel-16 7179700 171.8 ns/op 288 B/op 14 allocs/op
BenchmarkFieldMapDiveFailure-16 3081728 384.4 ns/op 376 B/op 13 allocs/op
BenchmarkFieldMapDiveFailureParallel-16 6058137 204.0 ns/op 377 B/op 13 allocs/op
BenchmarkFieldMapDiveWithKeysSuccess-16 2544975 464.8 ns/op 288 B/op 14 allocs/op
BenchmarkFieldMapDiveWithKeysSuccessParallel-16 6661954 181.4 ns/op 288 B/op 14 allocs/op
BenchmarkFieldMapDiveWithKeysFailure-16 2435484 490.7 ns/op 553 B/op 16 allocs/op
BenchmarkFieldMapDiveWithKeysFailureParallel-16 4249617 282.0 ns/op 554 B/op 16 allocs/op
BenchmarkFieldCustomTypeSuccess-16 14943525 77.35 ns/op 32 B/op 2 allocs/op
BenchmarkFieldCustomTypeSuccessParallel-16 64051954 20.61 ns/op 32 B/op 2 allocs/op
BenchmarkFieldCustomTypeFailure-16 10721384 107.1 ns/op 184 B/op 3 allocs/op
BenchmarkFieldCustomTypeFailureParallel-16 18714495 69.77 ns/op 184 B/op 3 allocs/op
BenchmarkFieldOrTagSuccess-16 4063124 294.3 ns/op 16 B/op 1 allocs/op
BenchmarkFieldOrTagSuccessParallel-16 31903756 41.22 ns/op 18 B/op 1 allocs/op
BenchmarkFieldOrTagFailure-16 7748558 146.8 ns/op 216 B/op 5 allocs/op
BenchmarkFieldOrTagFailureParallel-16 13139854 92.05 ns/op 216 B/op 5 allocs/op
BenchmarkStructLevelValidationSuccess-16 16808389 70.25 ns/op 16 B/op 1 allocs/op
BenchmarkStructLevelValidationSuccessParallel-16 90686955 14.47 ns/op 16 B/op 1 allocs/op
BenchmarkStructLevelValidationFailure-16 5818791 200.2 ns/op 264 B/op 7 allocs/op
BenchmarkStructLevelValidationFailureParallel-16 11115874 107.5 ns/op 264 B/op 7 allocs/op
BenchmarkStructSimpleCustomTypeSuccess-16 7764956 151.9 ns/op 32 B/op 2 allocs/op
BenchmarkStructSimpleCustomTypeSuccessParallel-16 52316265 30.37 ns/op 32 B/op 2 allocs/op
BenchmarkStructSimpleCustomTypeFailure-16 4195429 277.2 ns/op 416 B/op 9 allocs/op
BenchmarkStructSimpleCustomTypeFailureParallel-16 7305661 164.6 ns/op 432 B/op 10 allocs/op
BenchmarkStructFilteredSuccess-16 6312625 186.1 ns/op 216 B/op 5 allocs/op
BenchmarkStructFilteredSuccessParallel-16 13684459 93.42 ns/op 216 B/op 5 allocs/op
BenchmarkStructFilteredFailure-16 6751482 171.2 ns/op 216 B/op 5 allocs/op
BenchmarkStructFilteredFailureParallel-16 14146070 86.93 ns/op 216 B/op 5 allocs/op
BenchmarkStructPartialSuccess-16 6544448 177.3 ns/op 224 B/op 4 allocs/op
BenchmarkStructPartialSuccessParallel-16 13951946 88.73 ns/op 224 B/op 4 allocs/op
BenchmarkStructPartialFailure-16 4075833 287.5 ns/op 440 B/op 9 allocs/op
BenchmarkStructPartialFailureParallel-16 7490805 161.3 ns/op 440 B/op 9 allocs/op
BenchmarkStructExceptSuccess-16 4107187 281.4 ns/op 424 B/op 8 allocs/op
BenchmarkStructExceptSuccessParallel-16 15979173 80.86 ns/op 208 B/op 3 allocs/op
BenchmarkStructExceptFailure-16 4434372 264.3 ns/op 424 B/op 8 allocs/op
BenchmarkStructExceptFailureParallel-16 8081367 154.1 ns/op 424 B/op 8 allocs/op
BenchmarkStructSimpleCrossFieldSuccess-16 6459542 183.4 ns/op 56 B/op 3 allocs/op
BenchmarkStructSimpleCrossFieldSuccessParallel-16 41013781 37.95 ns/op 56 B/op 3 allocs/op
BenchmarkStructSimpleCrossFieldFailure-16 4034998 292.1 ns/op 272 B/op 8 allocs/op
BenchmarkStructSimpleCrossFieldFailureParallel-16 11348446 115.3 ns/op 272 B/op 8 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccess-16 4448528 267.7 ns/op 64 B/op 4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccessParallel-16 26813619 48.33 ns/op 64 B/op 4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailure-16 3090646 384.5 ns/op 288 B/op 9 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailureParallel-16 9870906 129.5 ns/op 288 B/op 9 allocs/op
BenchmarkStructSimpleSuccess-16 10675562 109.5 ns/op 0 B/op 0 allocs/op
BenchmarkStructSimpleSuccessParallel-16 131159784 8.932 ns/op 0 B/op 0 allocs/op
BenchmarkStructSimpleFailure-16 4094979 286.6 ns/op 416 B/op 9 allocs/op
BenchmarkStructSimpleFailureParallel-16 7606663 157.9 ns/op 416 B/op 9 allocs/op
BenchmarkStructComplexSuccess-16 2073470 576.0 ns/op 224 B/op 5 allocs/op
BenchmarkStructComplexSuccessParallel-16 7821831 161.3 ns/op 224 B/op 5 allocs/op
BenchmarkStructComplexFailure-16 576358 2001 ns/op 3042 B/op 48 allocs/op
BenchmarkStructComplexFailureParallel-16 1000000 1171 ns/op 3041 B/op 48 allocs/op
BenchmarkOneof-16 22503973 52.82 ns/op 0 B/op 0 allocs/op
BenchmarkOneofParallel-16 8538474 140.4 ns/op 0 B/op 0 allocs/op
Complementary Software
Here is a list of software that complements using this library either pre or post validation.
- form - Decodes url.Values into Go value(s) and Encodes Go value(s) into url.Values. Dual Array and Full map support.
- mold - A general library to help modify or set data within data structures and other objects
How to Contribute
Make a pull request...
Maintenance and support for SDK major versions
See prior discussion here for more details.
This package is aligned with the Go release policy in that support is guaranteed for the two most recent major versions.
This does not mean the package will not work with older versions of Go, only that we reserve the right to increase the MSGV(Minimum Supported Go Version) when the need arises to address Security issues/patches, OS issues & support or newly introduced functionality that would greatly benefit the maintenance and/or usage of this package.
If and when the MSGV is increased it will be done so in a minimum of a Minor release bump.
License
Distributed under MIT License, please see license file within the code for more details.
Maintainers
This project has grown large enough that more than one person is required to properly support the community. If you are interested in becoming a maintainer please reach out to me https://github.com/deankarn
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