100 lines
3.1 KiB
Go
100 lines
3.1 KiB
Go
package main
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import (
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"fmt"
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"reflect"
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"gopkg.in/go-playground/validator.v8"
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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 `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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var validate *validator.Validate
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func main() {
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config := &validator.Config{TagName: "validate"}
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validate = validator.New(config)
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validate.RegisterStructValidation(UserStructLevelValidation, User{})
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validateStruct()
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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(v *validator.Validate, structLevel *validator.StructLevel) {
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user := structLevel.CurrentStruct.Interface().(User)
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if len(user.FirstName) == 0 && len(user.LastName) == 0 {
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structLevel.ReportError(reflect.ValueOf(user.FirstName), "FirstName", "fname", "fnameorlname")
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structLevel.ReportError(reflect.ValueOf(user.LastName), "LastName", "lname", "fnameorlname")
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}
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// plus can to more, even with different tag than "fnameorlname"
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}
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func validateStruct() {
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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.com",
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FavouriteColor: "#000",
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Addresses: []*Address{address},
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}
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// returns nil or ValidationErrors ( map[string]*FieldError )
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errs := validate.Struct(user)
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if errs != nil {
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fmt.Println(errs) // output: Key: 'User.LastName' Error:Field validation for 'LastName' failed on the 'fnameorlname' tag
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// Key: 'User.FirstName' Error:Field validation for 'FirstName' failed on the 'fnameorlname' tag
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err := errs.(validator.ValidationErrors)["User.FirstName"]
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fmt.Println(err.Field) // output: FirstName
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fmt.Println(err.Tag) // output: fnameorlname
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fmt.Println(err.Kind) // output: string
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fmt.Println(err.Type) // output: string
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fmt.Println(err.Param) // output:
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fmt.Println(err.Value) // output:
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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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