valis

package main

import (
	"fmt"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/is"
)

func main() {
	type User struct {
		Name string
		Age  int
	}

	u := &User{}
	if err := valis.Validate(
		&u,
		valis.Field(&u.Name, is.NonZero),
		valis.Field(&u.Age, is.Min(20)),
	); err != nil {
		fmt.Println(err)
	}

	u.Name = "Alice"
	u.Age = 20
	if err := valis.Validate(
		&u,
		valis.Field(&u.Name, is.NonZero),
		valis.Field(&u.Age, is.Min(20)),
	); err != nil {
		fmt.Println(err)
	}

}

Output:

(non_zero) .Name can't be blank (or zero)
(gte) .Age must be greater than or equal to 20

package main

import (
	"fmt"
	"github.com/soranoba/valis/to"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/is"
)

func main() {
	arr := []interface{}{0, 1, 2, 3, "1", "2", "3"}

	v := valis.NewValidator()
	if err := v.Validate(&arr, valis.Each(to.Int(is.Min(2)))); err != nil {
		fmt.Println(err)
	}

}

Output:

(gte) [0] must be greater than or equal to 2
(gte) [1] must be greater than or equal to 2
(gte) [4] must be greater than or equal to 2

package main

import (
	"fmt"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/is"
)

func main() {
	type User struct {
		Name string `json:"name"`
		Age  int    `json:"age"`
	}

	v := valis.NewValidator()
	v.SetErrorCollectorFactoryFunc(func() valis.ErrorCollector {
		// You can create ErrorCollectors yourself that will generate your own error.
		// If you want to change only the attribute name, please change NameResolver.
		return valis.NewStandardErrorCollector(valis.JSONLocationNameResolver)
	})

	u := User{}
	if err := v.Validate(
		&u,
		valis.Field(&u.Name, is.NonZero),
		valis.Field(&u.Age, is.Min(20)),
	); err != nil {
		fmt.Println(err)
	}

}

Output:

(non_zero) .name can't be blank (or zero)
(gte) .age must be greater than or equal to 20

package main

import (
	"fmt"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/is"
	"github.com/soranoba/valis/when"
)

func main() {
	arr := []interface{}{0, 1, 2, 3, "a", "b", "c", "A", "B", "C"}

	v := valis.NewValidator()

	if err := v.Validate(
		&arr,
		valis.Each(
			when.IsNumeric(is.In(1, 2, 3)).
				Else(is.In("a", "b", "c")),
		),
	); err != nil {
		fmt.Println(err)
	}

}

Output:

(inclusion) [0] is not included in [1 2 3]
(inclusion) [7] is not included in [a b c]
(inclusion) [8] is not included in [a b c]
(inclusion) [9] is not included in [a b c]

package main

import (
	"fmt"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/tagrule"
	"github.com/soranoba/valis/when"
)

func main() {
	type User struct {
		Name    *string `required:"true"`
		Age     int     `validate:"min=20"`
		Company struct {
			Location *string `required:"true"`
		}
	}

	v := valis.NewValidator()
	// Use the CommonRule if you want to automatically search and validate all hierarchies.
	v.SetCommonRules(when.IsStruct(valis.EachFields(tagrule.Required, tagrule.Validate)))

	user := User{}
	if err := v.Validate(&user); err != nil {
		fmt.Println(err)
	}

}

Output:

(required) .Name is required
(gte) .Age must be greater than or equal to 20
(required) .Company.Location is required

package main

import (
	"fmt"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/tagrule"
	"github.com/soranoba/valis/when"
)

func main() {
	type User struct {
		Name *string `required:"true"`
		Age  int     `validate:"min=20"`
	}

	v := valis.NewValidator()
	u := User{}
	if err := v.Validate(&u, when.IsStruct(valis.EachFields(tagrule.Required, tagrule.Validate))); err != nil {
		fmt.Println(err)
	}

}

Output:

(required) .Name is required
(gte) .Age must be greater than or equal to 20

package main

import (
	"encoding/json"
	"fmt"

	"github.com/soranoba/valis"
	"github.com/soranoba/valis/is"
	"github.com/soranoba/valis/translations"
	"golang.org/x/text/language"
	"golang.org/x/text/message"
	"golang.org/x/text/message/catalog"
)

func main() {
	type User struct {
		Name string
		Age  int
	}

	// It is recommended to have the catalog in a global variable etc. instead of creating it every time.
	// We welcome your contributions if it does not exist the language you use.
	c := translations.NewCatalog(catalog.Fallback(language.English))
	for _, f := range translations.AllPredefinedCatalogRegistrationFunc {
		c.Set(f)
	}

	u := User{}
	if err := valis.Validate(
		&u,
		valis.Field(&u.Name, is.NonZero),
		valis.Field(&u.Age, is.Min(20)),
	); err != nil {
		for _, lang := range []language.Tag{language.English, language.Japanese} {
			p := message.NewPrinter(lang, message.Catalog(c))
			// When you change the ErrorCollector and create errors other than ValidationError, you need an alternative.
			m := err.(*valis.ValidationError).Translate(p)
			b, _ := json.MarshalIndent(m, "", "  ")
			fmt.Printf("%s\n", b)
		}
	}

}

Output:

{
  ".Age": [
    "must be greater than or equal to 20"
  ],
  ".Name": [
    "can't be blank (or zero)"
  ]
}
{
  ".Age": [
    "は20より大きい値にする必要があります"
  ],
  ".Name": [
    "を空白にすることはできません"
  ]
}

package main

import (
	"errors"
	"fmt"

	"github.com/soranoba/valis"
)

type ValidatableUser struct {
	Name string
}

func (u *ValidatableUser) Validate() error {
	if u.Name == "" {
		return errors.New("name is empty")
	}
	return nil
}

func main() {
	v := valis.NewValidator()

	// *ValidatableUser is implemented `Validate() error`
	// Validate returns nil, when Name is not empty. Otherwise, it returns an error.
	user := ValidatableUser{}
	if err := v.Validate(&user, valis.ValidatableRule); err != nil {
		fmt.Println(err)
	}

}

Output:

(custom) name is empty