Package validator
================
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[](https://travis-ci.org/go-playground/validator)
[](https://coveralls.io/github/go-playground/validator?branch=master)
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[](https://pkg.go.dev/github.com/go-playground/validator/v10)
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 ](https://golang.org/src/database/sql/driver/types.go?s=1210:1293#L29 )
- 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 ](https://github.com/gin-gonic/gin ) web framework; upgrading from v8 to v9 in gin see [here ](https://github.com/go-playground/validator/tree/master/_examples/gin-upgrading-overriding )
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 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:
```go
err := validate.Struct(mystruct)
validationErrors := err.(validator.ValidationErrors)
```
Usage and documentation
------
Please see https://godoc.org/github.com/go-playground/validator for detailed usage docs.
##### Examples:
- [Simple ](https://github.com/go-playground/validator/blob/master/_examples/simple/main.go )
- [Custom Field Types ](https://github.com/go-playground/validator/blob/master/_examples/custom/main.go )
- [Struct Level ](https://github.com/go-playground/validator/blob/master/_examples/struct-level/main.go )
- [Translations & Custom Errors ](https://github.com/go-playground/validator/blob/master/_examples/translations/main.go )
- [Gin upgrade and/or override validator ](https://github.com/go-playground/validator/tree/v9/_examples/gin-upgrading-overriding )
- [wash - an example application putting it all together ](https://github.com/bluesuncorp/wash )
Benchmarks
------
###### Run on MacBook Pro (15-inch, 2017) go version go1.10.2 darwin/amd64
```go
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 ](https://github.com/go-playground/form ) - Decodes url.Values into Go value(s) and Encodes Go value(s) into url.Values. Dual Array and Full map support.
* [mold ](https://github.com/go-playground/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.
