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120 lines
3.7 KiB
120 lines
3.7 KiB
package main
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import (
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"fmt"
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"reflect"
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"strings"
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"github.com/go-playground/validator/v10"
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)
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// User contains user information
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type User struct {
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FirstName string `json:"fname"`
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LastName string `json:"lname"`
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Age uint8 `validate:"gte=0,lte=130"`
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Email string `json:"e-mail" validate:"required,email"`
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FavouriteColor string `validate:"hexcolor|rgb|rgba"`
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Addresses []*Address `validate:"required,dive,required"` // a person can have a home and cottage...
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}
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// Address houses a users address information
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type Address struct {
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Street string `validate:"required"`
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City string `validate:"required"`
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Planet string `validate:"required"`
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Phone string `validate:"required"`
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}
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// use a single instance of Validate, it caches struct info
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var validate *validator.Validate
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func main() {
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validate = validator.New()
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// register function to get tag name from json tags.
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validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
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name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
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if name == "-" {
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return ""
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}
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return name
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})
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// register validation for 'User'
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// NOTE: only have to register a non-pointer type for 'User', validator
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// interanlly dereferences during it's type checks.
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validate.RegisterStructValidation(UserStructLevelValidation, User{})
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// build 'User' info, normally posted data etc...
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address := &Address{
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Street: "Eavesdown Docks",
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Planet: "Persphone",
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Phone: "none",
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City: "Unknown",
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}
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user := &User{
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FirstName: "",
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LastName: "",
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Age: 45,
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Email: "Badger.Smith@gmail",
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FavouriteColor: "#000",
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Addresses: []*Address{address},
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}
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// returns InvalidValidationError for bad validation input, nil or ValidationErrors ( []FieldError )
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err := validate.Struct(user)
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if err != nil {
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// this check is only needed when your code could produce
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// an invalid value for validation such as interface with nil
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// value most including myself do not usually have code like this.
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if _, ok := err.(*validator.InvalidValidationError); ok {
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fmt.Println(err)
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return
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}
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for _, err := range err.(validator.ValidationErrors) {
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fmt.Println(err.Namespace()) // can differ when a custom TagNameFunc is registered or
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fmt.Println(err.Field()) // by passing alt name to ReportError like below
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fmt.Println(err.StructNamespace())
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fmt.Println(err.StructField())
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fmt.Println(err.Tag())
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fmt.Println(err.ActualTag())
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fmt.Println(err.Kind())
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fmt.Println(err.Type())
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fmt.Println(err.Value())
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fmt.Println(err.Param())
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fmt.Println()
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}
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// from here you can create your own error messages in whatever language you wish
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return
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}
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// save user to database
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}
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// UserStructLevelValidation contains custom struct level validations that don't always
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// make sense at the field validation level. For Example this function validates that either
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// FirstName or LastName exist; could have done that with a custom field validation but then
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// would have had to add it to both fields duplicating the logic + overhead, this way it's
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// only validated once.
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//
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// NOTE: you may ask why wouldn't I just do this outside of validator, because doing this way
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// hooks right into validator and you can combine with validation tags and still have a
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// common error output format.
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func UserStructLevelValidation(sl validator.StructLevel) {
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user := sl.Current().Interface().(User)
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if len(user.FirstName) == 0 && len(user.LastName) == 0 {
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sl.ReportError(user.FirstName, "fname", "FirstName", "fnameorlname", "")
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sl.ReportError(user.LastName, "lname", "LastName", "fnameorlname", "")
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}
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// plus can do more, even with different tag than "fnameorlname"
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}
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