validator_struct.go

package main

import (
	"encoding/json"
	"fmt"
	"github.com/go-playground/validator/v10"
)

func UnmarshalFoo(data []byte) (Foo, error) {
	var r Foo
	err := json.Unmarshal(data, &r)
	return r, err
}

func (r *Foo) MarshalFoo() ([]byte, error) {
	return json.Marshal(r)
}

type Foo struct {
	Property1  string   `json:"prop1" validate:"ne=BABA,required"`
	Property2  string   `json:"prop2" validate:"required"`
}


var validate *validator.Validate

func main() {
	fmt.Println("BEGIN")

	validate = validator.New()

	invalidInput:= "{\"prop1\":\"BABA\",\"prop2\":\"value2\"}"
	validInput := "{\"prop1\":\"value1\",\"prop2\":\"value2\"}"

	invalidInputBytes := []byte(invalidInput)
	validInputBytes := []byte(validInput)

	validObject, err := UnmarshalFoo(validInputBytes)
	if err != nil {
		fmt.Printf("ERROR UNMARSHAL: %s\n\n", err)
	}
	fmt.Printf("UNMARSHALED RESULT invalid input: %s\n\n", validObject)

	invalidObject, err := UnmarshalFoo(invalidInputBytes)
	if err != nil {
		fmt.Printf("ERROR UNMARSHAL: %s\n\n", err)
	}
	fmt.Printf("UNMARSHALED RESULT valid input: %s\n\n", invalidObject)

	errs := validate.Struct(invalidObject)
	if errs!= nil {
	     	for k, v := range errs.(validator.ValidationErrors) {
            		// Create error messages based on errors returned ...
            		fmt.Println(k, v)
            	}
	}else {
		fmt.Println("VALID INPUT")
	}

	errs = validate.Struct(validObject)
	if err != nil {
	     	for k, v := range errs.(validator.ValidationErrors) {
            		// Create error messages based on errors returned ...
            		fmt.Println(k, v)
            	}
	}else {
		fmt.Println("VALID INPUT")
	}

	fmt.Printf("END")
}