Package validator
================
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[](https://semaphoreci.com/joeybloggs/validator)
[](https://coveralls.io/github/go-playground/validator?branch=v9)
[](https://goreportcard.com/report/github.com/go-playground/validator)
[](https://godoc.org/gopkg.in/go-playground/validator.v9)
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/v9/_examples/gin-upgrading-overriding )
Installation
------------
Use go get.
go get gopkg.in/go-playground/validator.v9
Then import the validator package into your own code.
import "gopkg.in/go-playground/validator.v9"
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 http://godoc.org/gopkg.in/go-playground/validator.v9 for detailed usage docs.
##### Examples:
- [Simple ](https://github.com/go-playground/validator/blob/v9/_examples/simple/main.go )
- [Custom Field Types ](https://github.com/go-playground/validator/blob/v9/_examples/custom/main.go )
- [Struct Level ](https://github.com/go-playground/validator/blob/v9/_examples/struct-level/main.go )
- [Translations & Custom Errors ](https://github.com/go-playground/validator/blob/v9/_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 go1.9.2 darwin/amd64
```go
go test -bench=. -benchmem=true
BenchmarkFieldSuccess-8 20000000 79.9 ns/op 0 B/op 0 allocs/op
BenchmarkFieldSuccessParallel-8 50000000 25.0 ns/op 0 B/op 0 allocs/op
BenchmarkFieldFailure-8 5000000 281 ns/op 208 B/op 4 allocs/op
BenchmarkFieldFailureParallel-8 20000000 97.0 ns/op 208 B/op 4 allocs/op
BenchmarkFieldArrayDiveSuccess-8 3000000 591 ns/op 201 B/op 11 allocs/op
BenchmarkFieldArrayDiveSuccessParallel-8 10000000 195 ns/op 201 B/op 11 allocs/op
BenchmarkFieldArrayDiveFailure-8 2000000 878 ns/op 412 B/op 16 allocs/op
BenchmarkFieldArrayDiveFailureParallel-8 5000000 274 ns/op 413 B/op 16 allocs/op
BenchmarkFieldMapDiveSuccess-8 1000000 1279 ns/op 432 B/op 18 allocs/op
BenchmarkFieldMapDiveSuccessParallel-8 5000000 401 ns/op 432 B/op 18 allocs/op
BenchmarkFieldMapDiveFailure-8 1000000 1060 ns/op 512 B/op 16 allocs/op
BenchmarkFieldMapDiveFailureParallel-8 5000000 334 ns/op 512 B/op 16 allocs/op
BenchmarkFieldMapDiveWithKeysSuccess-8 1000000 1462 ns/op 480 B/op 21 allocs/op
BenchmarkFieldMapDiveWithKeysSuccessParallel-8 3000000 463 ns/op 480 B/op 21 allocs/op
BenchmarkFieldMapDiveWithKeysFailure-8 1000000 1414 ns/op 721 B/op 21 allocs/op
BenchmarkFieldMapDiveWithKeysFailureParallel-8 3000000 446 ns/op 721 B/op 21 allocs/op
BenchmarkFieldCustomTypeSuccess-8 10000000 211 ns/op 32 B/op 2 allocs/op
BenchmarkFieldCustomTypeSuccessParallel-8 20000000 65.9 ns/op 32 B/op 2 allocs/op
BenchmarkFieldCustomTypeFailure-8 5000000 270 ns/op 208 B/op 4 allocs/op
BenchmarkFieldCustomTypeFailureParallel-8 20000000 93.3 ns/op 208 B/op 4 allocs/op
BenchmarkFieldOrTagSuccess-8 2000000 729 ns/op 16 B/op 1 allocs/op
BenchmarkFieldOrTagSuccessParallel-8 5000000 367 ns/op 16 B/op 1 allocs/op
BenchmarkFieldOrTagFailure-8 3000000 472 ns/op 224 B/op 5 allocs/op
BenchmarkFieldOrTagFailureParallel-8 5000000 373 ns/op 224 B/op 5 allocs/op
BenchmarkStructLevelValidationSuccess-8 10000000 201 ns/op 32 B/op 2 allocs/op
BenchmarkStructLevelValidationSuccessParallel-8 20000000 66.3 ns/op 32 B/op 2 allocs/op
BenchmarkStructLevelValidationFailure-8 3000000 468 ns/op 304 B/op 8 allocs/op
BenchmarkStructLevelValidationFailureParallel-8 10000000 172 ns/op 304 B/op 8 allocs/op
BenchmarkStructSimpleCustomTypeSuccess-8 5000000 376 ns/op 32 B/op 2 allocs/op
BenchmarkStructSimpleCustomTypeSuccessParallel-8 20000000 126 ns/op 32 B/op 2 allocs/op
BenchmarkStructSimpleCustomTypeFailure-8 2000000 646 ns/op 424 B/op 9 allocs/op
BenchmarkStructSimpleCustomTypeFailureParallel-8 10000000 240 ns/op 440 B/op 10 allocs/op
BenchmarkStructFilteredSuccess-8 3000000 582 ns/op 288 B/op 9 allocs/op
BenchmarkStructFilteredSuccessParallel-8 10000000 198 ns/op 288 B/op 9 allocs/op
BenchmarkStructFilteredFailure-8 3000000 447 ns/op 256 B/op 7 allocs/op
BenchmarkStructFilteredFailureParallel-8 10000000 156 ns/op 256 B/op 7 allocs/op
BenchmarkStructPartialSuccess-8 3000000 536 ns/op 256 B/op 6 allocs/op
BenchmarkStructPartialSuccessParallel-8 10000000 175 ns/op 256 B/op 6 allocs/op
BenchmarkStructPartialFailure-8 2000000 738 ns/op 480 B/op 11 allocs/op
BenchmarkStructPartialFailureParallel-8 5000000 256 ns/op 480 B/op 11 allocs/op
BenchmarkStructExceptSuccess-8 2000000 835 ns/op 496 B/op 12 allocs/op
BenchmarkStructExceptSuccessParallel-8 10000000 163 ns/op 240 B/op 5 allocs/op
BenchmarkStructExceptFailure-8 2000000 682 ns/op 464 B/op 10 allocs/op
BenchmarkStructExceptFailureParallel-8 10000000 244 ns/op 464 B/op 10 allocs/op
BenchmarkStructSimpleCrossFieldSuccess-8 5000000 392 ns/op 72 B/op 3 allocs/op
BenchmarkStructSimpleCrossFieldSuccessParallel-8 20000000 126 ns/op 72 B/op 3 allocs/op
BenchmarkStructSimpleCrossFieldFailure-8 2000000 611 ns/op 304 B/op 8 allocs/op
BenchmarkStructSimpleCrossFieldFailureParallel-8 10000000 214 ns/op 304 B/op 8 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccess-8 3000000 567 ns/op 80 B/op 4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccessParallel-8 10000000 177 ns/op 80 B/op 4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailure-8 2000000 807 ns/op 320 B/op 9 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailureParallel-8 5000000 268 ns/op 320 B/op 9 allocs/op
BenchmarkStructSimpleSuccess-8 5000000 256 ns/op 0 B/op 0 allocs/op
BenchmarkStructSimpleSuccessParallel-8 20000000 76.3 ns/op 0 B/op 0 allocs/op
BenchmarkStructSimpleFailure-8 2000000 625 ns/op 424 B/op 9 allocs/op
BenchmarkStructSimpleFailureParallel-8 10000000 219 ns/op 424 B/op 9 allocs/op
BenchmarkStructComplexSuccess-8 1000000 1431 ns/op 128 B/op 8 allocs/op
BenchmarkStructComplexSuccessParallel-8 3000000 427 ns/op 128 B/op 8 allocs/op
BenchmarkStructComplexFailure-8 300000 4065 ns/op 3041 B/op 53 allocs/op
BenchmarkStructComplexFailureParallel-8 1000000 1478 ns/op 3041 B/op 53 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.
