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

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:

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

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

Fields:

Tag	Description
eqcsfield	Field Equals Another Field (relative)
eqfield	Field Equals Another Field
fieldcontains	NOT DOCUMENTED IN doc.go
fieldexcludes	NOT DOCUMENTED IN doc.go
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
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 With
endswith	Ends With
excludes	Excludes
excludesall	Excludes All
excludesrune	Excludes Rune
lowercase	Lowercase
multibyte	Multi-Byte Characters
number	NOT DOCUMENTED IN doc.go
numeric	Numeric
printascii	Printable ASCII
startsnotwith	Starts Not With
startswith	Starts With
uppercase	Uppercase

Format:

Tag	Description
base64	Base64 String
base64url	Base64URL 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
datetime	Datetime
e164	e164 formatted phone number
email	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
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
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
semver	Semantic Versioning 2.0.0
ulid	Universally Unique Lexicographically Sortable Identifier ULID

Comparisons:

Tag	Description
eq	Equals
gt	Greater than
gte	Greater than or equal
lt	Less Than
lte	Less Than or Equal
ne	Not Equal

Other:

Tag	Description
dir	Directory
file	File path
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

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 (15-inch, 2017) go version go1.10.2 darwin/amd64

goos: darwin
goarch: amd64
pkg: github.com/go-playground/validator
BenchmarkFieldSuccess-8                                         20000000                83.6 ns/op             0 B/op          0 allocs/op
BenchmarkFieldSuccessParallel-8                                 50000000                26.8 ns/op             0 B/op          0 allocs/op
BenchmarkFieldFailure-8                                          5000000               291 ns/op             208 B/op          4 allocs/op
BenchmarkFieldFailureParallel-8                                 20000000               107 ns/op             208 B/op          4 allocs/op
BenchmarkFieldArrayDiveSuccess-8                                 2000000               623 ns/op             201 B/op         11 allocs/op
BenchmarkFieldArrayDiveSuccessParallel-8                        10000000               237 ns/op             201 B/op         11 allocs/op
BenchmarkFieldArrayDiveFailure-8                                 2000000               859 ns/op             412 B/op         16 allocs/op
BenchmarkFieldArrayDiveFailureParallel-8                         5000000               335 ns/op             413 B/op         16 allocs/op
BenchmarkFieldMapDiveSuccess-8                                   1000000              1292 ns/op             432 B/op         18 allocs/op
BenchmarkFieldMapDiveSuccessParallel-8                           3000000               467 ns/op             432 B/op         18 allocs/op
BenchmarkFieldMapDiveFailure-8                                   1000000              1082 ns/op             512 B/op         16 allocs/op
BenchmarkFieldMapDiveFailureParallel-8                           5000000               425 ns/op             512 B/op         16 allocs/op
BenchmarkFieldMapDiveWithKeysSuccess-8                           1000000              1539 ns/op             480 B/op         21 allocs/op
BenchmarkFieldMapDiveWithKeysSuccessParallel-8                   3000000               613 ns/op             480 B/op         21 allocs/op
BenchmarkFieldMapDiveWithKeysFailure-8                           1000000              1413 ns/op             721 B/op         21 allocs/op
BenchmarkFieldMapDiveWithKeysFailureParallel-8                   3000000               575 ns/op             721 B/op         21 allocs/op
BenchmarkFieldCustomTypeSuccess-8                               10000000               216 ns/op              32 B/op          2 allocs/op
BenchmarkFieldCustomTypeSuccessParallel-8                       20000000                82.2 ns/op            32 B/op          2 allocs/op
BenchmarkFieldCustomTypeFailure-8                                5000000               274 ns/op             208 B/op          4 allocs/op
BenchmarkFieldCustomTypeFailureParallel-8                       20000000               116 ns/op             208 B/op          4 allocs/op
BenchmarkFieldOrTagSuccess-8                                     2000000               740 ns/op              16 B/op          1 allocs/op
BenchmarkFieldOrTagSuccessParallel-8                             3000000               474 ns/op              16 B/op          1 allocs/op
BenchmarkFieldOrTagFailure-8                                     3000000               471 ns/op             224 B/op          5 allocs/op
BenchmarkFieldOrTagFailureParallel-8                             3000000               414 ns/op             224 B/op          5 allocs/op
BenchmarkStructLevelValidationSuccess-8                         10000000               213 ns/op              32 B/op          2 allocs/op
BenchmarkStructLevelValidationSuccessParallel-8                 20000000                91.8 ns/op            32 B/op          2 allocs/op
BenchmarkStructLevelValidationFailure-8                          3000000               473 ns/op             304 B/op          8 allocs/op
BenchmarkStructLevelValidationFailureParallel-8                 10000000               234 ns/op             304 B/op          8 allocs/op
BenchmarkStructSimpleCustomTypeSuccess-8                         5000000               385 ns/op              32 B/op          2 allocs/op
BenchmarkStructSimpleCustomTypeSuccessParallel-8                10000000               161 ns/op              32 B/op          2 allocs/op
BenchmarkStructSimpleCustomTypeFailure-8                         2000000               640 ns/op             424 B/op          9 allocs/op
BenchmarkStructSimpleCustomTypeFailureParallel-8                 5000000               318 ns/op             440 B/op         10 allocs/op
BenchmarkStructFilteredSuccess-8                                 2000000               597 ns/op             288 B/op          9 allocs/op
BenchmarkStructFilteredSuccessParallel-8                        10000000               266 ns/op             288 B/op          9 allocs/op
BenchmarkStructFilteredFailure-8                                 3000000               454 ns/op             256 B/op          7 allocs/op
BenchmarkStructFilteredFailureParallel-8                        10000000               214 ns/op             256 B/op          7 allocs/op
BenchmarkStructPartialSuccess-8                                  3000000               502 ns/op             256 B/op          6 allocs/op
BenchmarkStructPartialSuccessParallel-8                         10000000               225 ns/op             256 B/op          6 allocs/op
BenchmarkStructPartialFailure-8                                  2000000               702 ns/op             480 B/op         11 allocs/op
BenchmarkStructPartialFailureParallel-8                          5000000               329 ns/op             480 B/op         11 allocs/op
BenchmarkStructExceptSuccess-8                                   2000000               793 ns/op             496 B/op         12 allocs/op
BenchmarkStructExceptSuccessParallel-8                          10000000               193 ns/op             240 B/op          5 allocs/op
BenchmarkStructExceptFailure-8                                   2000000               639 ns/op             464 B/op         10 allocs/op
BenchmarkStructExceptFailureParallel-8                           5000000               300 ns/op             464 B/op         10 allocs/op
BenchmarkStructSimpleCrossFieldSuccess-8                         3000000               417 ns/op              72 B/op          3 allocs/op
BenchmarkStructSimpleCrossFieldSuccessParallel-8                10000000               163 ns/op              72 B/op          3 allocs/op
BenchmarkStructSimpleCrossFieldFailure-8                         2000000               645 ns/op             304 B/op          8 allocs/op
BenchmarkStructSimpleCrossFieldFailureParallel-8                 5000000               285 ns/op             304 B/op          8 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccess-8              3000000               588 ns/op              80 B/op          4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccessParallel-8     10000000               221 ns/op              80 B/op          4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailure-8              2000000               868 ns/op             320 B/op          9 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailureParallel-8      5000000               337 ns/op             320 B/op          9 allocs/op
BenchmarkStructSimpleSuccess-8                                   5000000               260 ns/op               0 B/op          0 allocs/op
BenchmarkStructSimpleSuccessParallel-8                          20000000                90.6 ns/op             0 B/op          0 allocs/op
BenchmarkStructSimpleFailure-8                                   2000000               619 ns/op             424 B/op          9 allocs/op
BenchmarkStructSimpleFailureParallel-8                           5000000               296 ns/op             424 B/op          9 allocs/op
BenchmarkStructComplexSuccess-8                                  1000000              1454 ns/op             128 B/op          8 allocs/op
BenchmarkStructComplexSuccessParallel-8                          3000000               579 ns/op             128 B/op          8 allocs/op
BenchmarkStructComplexFailure-8                                   300000              4140 ns/op            3041 B/op         53 allocs/op
BenchmarkStructComplexFailureParallel-8                          1000000              2127 ns/op            3041 B/op         53 allocs/op
BenchmarkOneof-8                                                10000000               140 ns/op               0 B/op          0 allocs/op
BenchmarkOneofParallel-8                                        20000000                70.1 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...

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