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.
- 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
- 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:
Struct & Field validation
```go
package main
import (
"fmt"
"gopkg.in/go-playground/validator.v9"
)
// User contains user information
type User struct {
FirstName string `validate:"required"`
LastName string `validate:"required"`
Age uint8 `validate:"gte=0,lte=130"`
Email string `validate:"required,email"`
FavouriteColor string `validate:"iscolor"` // alias for 'hexcolor|rgb|rgba|hsl|hsla'
Addresses []*Address `validate:"required,dive,required"` // a person can have a home and cottage...
}
// Address houses a users address information
type Address struct {
Street string `validate:"required"`
City string `validate:"required"`
Planet string `validate:"required"`
Phone string `validate:"required"`
}
// use a single instance of Validate, it caches struct info
var validate *validator.Validate
func main() {
validate = validator.New()
validateStruct()
validateVariable()
}
func validateStruct() {
address := & Address{
Street: "Eavesdown Docks",
Planet: "Persphone",
Phone: "none",
}
user := & User{
FirstName: "Badger",
LastName: "Smith",
Age: 135,
Email: "Badger.Smith@gmail.com",
FavouriteColor: "#000-",
Addresses: []*Address{address},
}
// returns nil or ValidationErrors ( map[string]*FieldError )
err := validate.Struct(user)
if err != nil {
// this check is only needed when your code could produce
// an invalid value for validation such as interface with nil
// value most including myself do not usually have code like this.
if _, ok := err.(*validator.InvalidValidationError); ok {
fmt.Println(err)
return
}
for _, err := range err.(validator.ValidationErrors) {
fmt.Println(err.Namespace())
fmt.Println(err.Field())
fmt.Println(err.StructNamespace()) // can differ when a custom TagNameFunc is registered or
fmt.Println(err.StructField()) // by passing alt name to ReportError like below
fmt.Println(err.Tag())
fmt.Println(err.ActualTag())
fmt.Println(err.Kind())
fmt.Println(err.Type())
fmt.Println(err.Value())
fmt.Println(err.Param())
fmt.Println()
}
// from here you can create your own error messages in whatever language you wish
return
}
// save user to database
}
func validateVariable() {
myEmail := "joeybloggs.gmail.com"
errs := validate.Var(myEmail, "required,email")
if errs != nil {
fmt.Println(errs) // output: Key: "" Error:Field validation for "" failed on the "email" tag
return
}
// email ok, move on
}
```
Custom Field Type
```go
package main
import (
"database/sql"
"database/sql/driver"
"fmt"
"reflect"
"gopkg.in/go-playground/validator.v9"
)
// DbBackedUser User struct
type DbBackedUser struct {
Name sql.NullString `validate:"required"`
Age sql.NullInt64 `validate:"required"`
}
// use a single instance of Validate, it caches struct info
var validate *validator.Validate
func main() {
validate = validator.New()
// register all sql.Null* types to use the ValidateValuer CustomTypeFunc
validate.RegisterCustomTypeFunc(ValidateValuer, sql.NullString{}, sql.NullInt64{}, sql.NullBool{}, sql.NullFloat64{})
// build object for validation
x := DbBackedUser{Name: sql.NullString{String: "", Valid: true}, Age: sql.NullInt64{Int64: 0, Valid: false}}
err := validate.Struct(x)
if err != nil {
fmt.Printf("Err(s):\n%+v\n", err)
}
}
// ValidateValuer implements validator.CustomTypeFunc
func ValidateValuer(field reflect.Value) interface{} {
if valuer, ok := field.Interface().(driver.Valuer); ok {
val, err := valuer.Value()
if err == nil {
return val
}
// handle the error how you want
}
return nil
}
```
Struct Level Validation
```go
package main
import (
"fmt"
"gopkg.in/go-playground/validator.v9"
)
// User contains user information
type User struct {
FirstName string `json:"fname"`
LastName string `json:"lname"`
Age uint8 `validate:"gte=0,lte=130"`
Email string `validate:"required,email"`
FavouriteColor string `validate:"hexcolor|rgb|rgba"`
Addresses []*Address `validate:"required,dive,required"` // a person can have a home and cottage...
}
// Address houses a users address information
type Address struct {
Street string `validate:"required"`
City string `validate:"required"`
Planet string `validate:"required"`
Phone string `validate:"required"`
}
// use a single instance of Validate, it caches struct info
var validate *validator.Validate
func main() {
validate = validator.New()
// register validation for 'User'
// NOTE: only have to register a non-pointer type for 'User', validator
// interanlly dereferences during it's type checks.
validate.RegisterStructValidation(UserStructLevelValidation, User{})
// build 'User' info, normally posted data etc...
address := & Address{
Street: "Eavesdown Docks",
Planet: "Persphone",
Phone: "none",
City: "Unknown",
}
user := & User{
FirstName: "",
LastName: "",
Age: 45,
Email: "Badger.Smith@gmail.com",
FavouriteColor: "#000",
Addresses: []*Address{address},
}
// returns InvalidValidationError for bad validation input, nil or ValidationErrors ( []FieldError )
err := validate.Struct(user)
if err != nil {
// this check is only needed when your code could produce
// an invalid value for validation such as interface with nil
// value most including myself do not usually have code like this.
if _, ok := err.(*validator.InvalidValidationError); ok {
fmt.Println(err)
return
}
for _, err := range err.(validator.ValidationErrors) {
fmt.Println(err.Namespace())
fmt.Println(err.Field())
fmt.Println(err.StructNamespace()) // can differ when a custom TagNameFunc is registered or
fmt.Println(err.StructField()) // by passing alt name to ReportError like below
fmt.Println(err.Tag())
fmt.Println(err.ActualTag())
fmt.Println(err.Kind())
fmt.Println(err.Type())
fmt.Println(err.Value())
fmt.Println(err.Param())
fmt.Println()
}
// from here you can create your own error messages in whatever language you wish
return
}
// save user to database
}
// UserStructLevelValidation contains custom struct level validations that don't always
// make sense at the field validation level. For Example this function validates that either
// FirstName or LastName exist; could have done that with a custom field validation but then
// would have had to add it to both fields duplicating the logic + overhead, this way it's
// only validated once.
//
// NOTE: you may ask why wouldn't I just do this outside of validator, because doing this way
// hooks right into validator and you can combine with validation tags and still have a
// common error output format.
func UserStructLevelValidation(sl validator.StructLevel) {
user := sl.Current().Interface().(User)
if len(user.FirstName) == 0 & & len(user.LastName) == 0 {
sl.ReportError(user.FirstName, "FirstName", "fname", "fnameorlname", "")
sl.ReportError(user.LastName, "LastName", "lname", "fnameorlname", "")
}
// plus can to more, even with different tag than "fnameorlname"
}
```
Benchmarks
------
###### Run on MacBook Pro (Retina, 15-inch, Late 2013) 2.6 GHz Intel Core i7 16 GB 1600 MHz DDR3 using Go version go1.7 darwin/amd64
```go
BenchmarkFieldSuccess-8 20000000 108 ns/op 0 B/op 0 allocs/op
BenchmarkFieldSuccessParallel-8 50000000 35.7 ns/op 0 B/op 0 allocs/op
BenchmarkFieldFailure-8 5000000 320 ns/op 192 B/op 4 allocs/op
BenchmarkFieldFailureParallel-8 20000000 113 ns/op 192 B/op 4 allocs/op
BenchmarkFieldDiveSuccess-8 2000000 726 ns/op 201 B/op 11 allocs/op
BenchmarkFieldDiveSuccessParallel-8 10000000 263 ns/op 201 B/op 11 allocs/op
BenchmarkFieldDiveFailure-8 2000000 939 ns/op 396 B/op 16 allocs/op
BenchmarkFieldDiveFailureParallel-8 5000000 382 ns/op 397 B/op 16 allocs/op
BenchmarkFieldCustomTypeSuccess-8 5000000 268 ns/op 32 B/op 2 allocs/op
BenchmarkFieldCustomTypeSuccessParallel-8 20000000 87.8 ns/op 32 B/op 2 allocs/op
BenchmarkFieldCustomTypeFailure-8 5000000 310 ns/op 192 B/op 4 allocs/op
BenchmarkFieldCustomTypeFailureParallel-8 20000000 131 ns/op 192 B/op 4 allocs/op
BenchmarkFieldOrTagSuccess-8 2000000 889 ns/op 16 B/op 1 allocs/op
BenchmarkFieldOrTagSuccessParallel-8 5000000 418 ns/op 16 B/op 1 allocs/op
BenchmarkFieldOrTagFailure-8 3000000 546 ns/op 208 B/op 5 allocs/op
BenchmarkFieldOrTagFailureParallel-8 3000000 450 ns/op 208 B/op 5 allocs/op
BenchmarkStructLevelValidationSuccess-8 5000000 336 ns/op 32 B/op 2 allocs/op
BenchmarkStructLevelValidationSuccessParallel-8 20000000 123 ns/op 32 B/op 2 allocs/op
BenchmarkStructLevelValidationFailure-8 2000000 611 ns/op 288 B/op 8 allocs/op
BenchmarkStructLevelValidationFailureParallel-8 5000000 298 ns/op 288 B/op 8 allocs/op
BenchmarkStructSimpleCustomTypeSuccess-8 2000000 555 ns/op 32 B/op 2 allocs/op
BenchmarkStructSimpleCustomTypeSuccessParallel-8 10000000 197 ns/op 32 B/op 2 allocs/op
BenchmarkStructSimpleCustomTypeFailure-8 2000000 811 ns/op 392 B/op 9 allocs/op
BenchmarkStructSimpleCustomTypeFailureParallel-8 5000000 370 ns/op 408 B/op 10 allocs/op
BenchmarkStructPartialSuccess-8 2000000 676 ns/op 256 B/op 6 allocs/op
BenchmarkStructPartialSuccessParallel-8 5000000 301 ns/op 256 B/op 6 allocs/op
BenchmarkStructPartialFailure-8 1000000 1001 ns/op 464 B/op 11 allocs/op
BenchmarkStructPartialFailureParallel-8 3000000 436 ns/op 464 B/op 11 allocs/op
BenchmarkStructExceptSuccess-8 1000000 1038 ns/op 480 B/op 12 allocs/op
BenchmarkStructExceptSuccessParallel-8 10000000 281 ns/op 240 B/op 5 allocs/op
BenchmarkStructExceptFailure-8 2000000 863 ns/op 448 B/op 10 allocs/op
BenchmarkStructExceptFailureParallel-8 3000000 379 ns/op 448 B/op 10 allocs/op
BenchmarkStructSimpleCrossFieldSuccess-8 3000000 549 ns/op 72 B/op 3 allocs/op
BenchmarkStructSimpleCrossFieldSuccessParallel-8 10000000 192 ns/op 72 B/op 3 allocs/op
BenchmarkStructSimpleCrossFieldFailure-8 2000000 783 ns/op 288 B/op 8 allocs/op
BenchmarkStructSimpleCrossFieldFailureParallel-8 5000000 296 ns/op 288 B/op 8 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccess-8 2000000 837 ns/op 80 B/op 4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldSuccessParallel-8 5000000 284 ns/op 80 B/op 4 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailure-8 1000000 1110 ns/op 304 B/op 9 allocs/op
BenchmarkStructSimpleCrossStructCrossFieldFailureParallel-8 3000000 416 ns/op 304 B/op 9 allocs/op
BenchmarkStructSimpleSuccess-8 5000000 380 ns/op 0 B/op 0 allocs/op
BenchmarkStructSimpleSuccessParallel-8 20000000 114 ns/op 0 B/op 0 allocs/op
BenchmarkStructSimpleFailure-8 2000000 760 ns/op 392 B/op 9 allocs/op
BenchmarkStructSimpleFailureParallel-8 5000000 353 ns/op 392 B/op 9 allocs/op
BenchmarkStructComplexSuccess-8 1000000 2100 ns/op 128 B/op 8 allocs/op
BenchmarkStructComplexSuccessParallel-8 2000000 662 ns/op 128 B/op 8 allocs/op
BenchmarkStructComplexFailure-8 200000 5080 ns/op 2833 B/op 53 allocs/op
BenchmarkStructComplexFailureParallel-8 1000000 2159 ns/op 2833 B/op 53 allocs/op
```
Complimentary Software
----------------------
Here is a list of software that compliments 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.
* [Conform ](https://github.com/leebenson/conform ) - Trims, sanitizes & scrubs data based on struct tags.
How to Contribute
------
Make a pull request...
License
------
Distributed under MIT License, please see license file in code for more details.
