Package validator
================

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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.  
-   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)

Installation
------------

Use go get.

	go get gopkg.in/bluesuncorp/validator.v6

or to update

	go get -u gopkg.in/bluesuncorp/validator.v6

Then import the validator package into your own code.

	import "gopkg.in/bluesuncorp/validator.v6"

Usage and documentation
------

Please see http://godoc.org/gopkg.in/bluesuncorp/validator.v6 for detailed usage docs.

##### Examples:

Struct & Field validation
```go
package main

import (
	"fmt"

	"gopkg.in/bluesuncorp/validator.v6"
)

// 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:"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"`
}

var validate *validator.Validate

func main() {

	config := validator.Config{
		TagName:         "validate",
		ValidationFuncs: validator.BakedInValidators,
	}

	validate = validator.New(config)

	validateStruct()
	validateField()
}

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 )
	errs := validate.Struct(user)

	if errs != nil {

		fmt.Println(errs) // output: Key: "User.Age" Error:Field validation for "Age" failed on the "lte" tag
		//	                         Key: "User.Addresses[0].City" Error:Field validation for "City" failed on the "required" tag
		err := errs["User.Addresses[0].City"]
		fmt.Println(err.Field) // output: City
		fmt.Println(err.Tag)   // output: required
		fmt.Println(err.Kind)  // output: string
		fmt.Println(err.Type)  // output: string
		fmt.Println(err.Param) // output:
		fmt.Println(err.Value) // output:

		// from here you can create your own error messages in whatever language you wish
		return
	}

	// save user to database
}

func validateField() {
	myEmail := "joeybloggs.gmail.com"

	errs := validate.Field(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 (
	"errors"
	"fmt"
	"reflect"

	sql "database/sql/driver"

	"gopkg.in/bluesuncorp/validator.v6"
)

var validate *validator.Validate

type valuer struct {
	Name string
}

func (v valuer) Value() (sql.Value, error) {

	if v.Name == "errorme" {
		return nil, errors.New("some kind of error")
	}

	if v.Name == "blankme" {
		return "", nil
	}

	if len(v.Name) == 0 {
		return nil, nil
	}

	return v.Name, nil
}

// ValidateValuerType implements validator.CustomTypeFunc
func ValidateValuerType(field reflect.Value) interface{} {
	if valuer, ok := field.Interface().(sql.Valuer); ok {
		val, err := valuer.Value()
		if err != nil {
			// handle the error how you want
			return nil
		}

		return val
	}

	return nil
}

func main() {

	customTypes := map[reflect.Type]validator.CustomTypeFunc{}
	customTypes[reflect.TypeOf((*sql.Valuer)(nil))] = ValidateValuerType
	customTypes[reflect.TypeOf(valuer{})] = ValidateValuerType

	config := validator.Config{
		TagName:         "validate",
		ValidationFuncs: validator.BakedInValidators,
		CustomTypeFuncs: customTypes,
	}

	validate = validator.New(config)

	validateCustomFieldType()
}

func validateCustomFieldType() {
	val := valuer{
		Name: "blankme",
	}

	errs := validate.Field(val, "required")
	if errs != nil {
		fmt.Println(errs) // output: Key: "" Error:Field validation for "" failed on the "required" tag
		return
	}

	// all ok
}

```

Benchmarks
------
###### Run on MacBook Pro (Retina, 15-inch, Late 2013) 2.6 GHz Intel Core i7 16 GB 1600 MHz DDR3
NOTE: allocations for structs are up from v5, however ns/op for parallel operations are way down.
It was a decicion not to cache struct info because although it reduced allocation to v5 levels, it
hurt parallel performance too much.
```go
$ go test -cpu=4 -bench=. -benchmem=true
PASS
BenchmarkFieldSuccess-4	 					 5000000	       318 ns/op	      16 B/op	       1 allocs/op
BenchmarkFieldFailure-4	 					 5000000	       316 ns/op	      16 B/op	       1 allocs/op
BenchmarkFieldCustomTypeSuccess-4	 		 3000000	       492 ns/op	      32 B/op	       2 allocs/op
BenchmarkFieldCustomTypeFailure-4	 		 2000000	       843 ns/op	     416 B/op	       6 allocs/op
BenchmarkFieldOrTagSuccess-4	  			  500000	      2384 ns/op	      20 B/op	       2 allocs/op
BenchmarkFieldOrTagFailure-4	 			 1000000	      1295 ns/op	     384 B/op	       6 allocs/op
BenchmarkStructSimpleSuccess-4	 			 1000000	      1175 ns/op	      24 B/op	       3 allocs/op
BenchmarkStructSimpleFailure-4	 			 1000000	      1822 ns/op	     529 B/op	      11 allocs/op
BenchmarkStructSimpleCustomTypeSuccess-4	 1000000	      1302 ns/op	      56 B/op	       5 allocs/op
BenchmarkStructSimpleCustomTypeFailure-4	 1000000	      1847 ns/op	     577 B/op	      13 allocs/op
BenchmarkStructSimpleSuccessParallel-4	 	 5000000	       339 ns/op	      24 B/op	       3 allocs/op
BenchmarkStructSimpleFailureParallel-4	 	 2000000	       733 ns/op	     529 B/op	      11 allocs/op
BenchmarkStructComplexSuccess-4	  			  200000	      7104 ns/op	     368 B/op	      30 allocs/op
BenchmarkStructComplexFailure-4	  			  100000	     11996 ns/op	    2861 B/op	      72 allocs/op
BenchmarkStructComplexSuccessParallel-4	 	 1000000	      2252 ns/op	     368 B/op	      30 allocs/op
BenchmarkStructComplexFailureParallel-4	  	  300000	      4691 ns/op	    2862 B/op	      72 allocs/op
```

How to Contribute
------

There will always be a development branch for each version i.e. `v1-development`. In order to contribute, 
please make your pull requests against those branches.

If the changes being proposed or requested are breaking changes, please create an issue, for discussion 
or create a pull request against the highest development branch for example this package has a 
v1 and v1-development branch however, there will also be a v2-development brach even though v2 doesn't exist yet.

I strongly encourage everyone whom creates a custom validation function to contribute them and
help make this package even better.

License
------
Distributed under MIT License, please see license file in code for more details.