🔎 Validation
Validator package
Fiber can make great use of the validator package to ensure correct validation of data to store.
You can find the detailed descriptions of the validations used in the fields contained on the structs below:
Validation Example
package main
import (
"fmt"
"log"
"strings"
"github.com/go-playground/validator/v10"
"github.com/gofiber/fiber/v2"
)
type (
User struct {
Name string `validate:"required,min=5,max=20"` // Required field, min 5 char long max 20
Age int `validate:"required,teener"` // Required field, and client needs to implement our 'teener' tag format which we'll see later
}
ErrorResponse struct {
Error bool
FailedField string
Tag string
Value interface{}
}
XValidator struct {
validator *validator.Validate
}
GlobalErrorHandlerResp struct {
Success bool `json:"success"`
Message string `json:"message"`
}
)
// This is the validator instance
// for more information see: https://github.com/go-playground/validator
var validate = validator.New()
func (v XValidator) Validate(data interface{}) []ErrorResponse {
validationErrors := []ErrorResponse{}
errs := validate.Struct(data)
if errs != nil {
for _, err := range errs.(validator.ValidationErrors) {
// In this case data object is actually holding the User struct
var elem ErrorResponse
elem.FailedField = err.Field() // Export struct field name
elem.Tag = err.Tag() // Export struct tag
elem.Value = err.Value() // Export field value
elem.Error = true
validationErrors = append(validationErrors, elem)
}
}
return validationErrors
}
func main() {
myValidator := &XValidator{
validator: validate,
}
app := fiber.New(fiber.Config{
// Global custom error handler
ErrorHandler: func(c *fiber.Ctx, err error) error {
return c.Status(fiber.StatusBadRequest).JSON(GlobalErrorHandlerResp{
Success: false,
Message: err.Error(),
})
},
})
// Custom struct validation tag format
myValidator.validator.RegisterValidation("teener", func(fl validator.FieldLevel) bool {
// User.Age needs to fit our needs, 12-18 years old.
return fl.Field().Int() >= 12 && fl.Field().Int() <= 18
})
app.Get("/", func(c *fiber.Ctx) error {
user := &User{
Name: c.Query("name"),
Age: c.QueryInt("age"),
}
// Validation
if errs := myValidator.Validate(user); len(errs) > 0 && errs[0].Error {
errMsgs := make([]string, 0)
for _, err := range errs {
errMsgs = append(errMsgs, fmt.Sprintf(
"[%s]: '%v' | Needs to implement '%s'",
err.FailedField,
err.Value,
err.Tag,
))
}
return &fiber.Error{
Code: fiber.ErrBadRequest.Code,
Message: strings.Join(errMsgs, " and "),
}
}
// Logic, validated with success
return c.SendString("Hello, World!")
})
log.Fatal(app.Listen(":3000"))
}
/**
OUTPUT
[1]
Request:
GET http://127.0.0.1:3000/
Response:
{"success":false,"message":"[Name]: '' | Needs to implement 'required' and [Age]: '0' | Needs to implement 'required'"}
[2]
Request:
GET http://127.0.0.1:3000/?name=efdal&age=9
Response:
{"success":false,"message":"[Age]: '9' | Needs to implement 'teener'"}
[3]
Request:
GET http://127.0.0.1:3000/?name=efdal&age=
Response:
{"success":false,"message":"[Age]: '0' | Needs to implement 'required'"}
[4]
Request:
GET http://127.0.0.1:3000/?name=efdal&age=18
Response:
Hello, World!
**/