Validations

Validations provides a means to validate GORM models when creating and updating them.

Register GORM Callbacks

Validations uses GORM callbacks to handle validations, so you will need to register callbacks first:

package main
import (
  "github.com/a69/validations"
  "github.com/jinzhu/gorm"
)

func main() {
  db, err := gorm.Open("sqlite3", "demo_db")
  if err!=nil{
    panic(err)
  }
  validations.RegisterCallbacks(db)
}

Usage

After callbacks have been registered, attempting to create or update any record will trigger the Validate method that you have implemented for your model. If your implementation adds or returns an error, the attempt will be aborted.

type User struct {
  gorm.Model
  Age uint
}

func (user User) Validate(db *gorm.DB) {
  if user.Age <= 18 {
    db.AddError(errors.New("age need to be 18+"))
  }
}

db.Create(&User{Age: 10})         // won't insert the record into database, as the `Validate` method will return error

var user User{Age: 20}
db.Create(&user)                  // user with age 20 will be inserted into database
db.Model(&user).Update("age", 10) // user's age won't be updated, will return error `age need to be 18+`

// If you have added more than one error, could get all of them with `db.GetErrors()`
func (user User) Validate(db *gorm.DB) {
  if user.Age <= 18 {
    db.AddError(errors.New("age need to be 18+"))
  }
  if user.Name == "" {
    db.AddError(errors.New("name can't be blank"))
  }
}

db.Create(&User{}).GetErrors() // => []error{"age need to be 18+", "name can't be blank"}

Govalidator integration

Validations supports govalidator, so you could add a tag into your struct for some common validations, such as check required, numeric, length, etc.

type User struct {
  gorm.Model
  Name           string `valid:"required"`
  Password       string `valid:"length(6|20)"`
  SecurePassword string `valid:"numeric"`
  Email          string `valid:"email"`
}

Customize errors on form field

If you want to create specific validation errors for each form field, you could register your error like this:

func (user User) Validate(db *gorm.DB) {
  if user.Age <= 18 {
    db.AddError(validations.NewError(user, "Age", "age need to be 18+"))
  }
}

License