Library/models/error.go

package models

import "fmt"

// ErrUsernameExists represents a "UsernameAlreadyExists" kind of error.
type ErrUsernameExists struct {
	UserID   int64
	Username string
}

// IsErrUsernameExists checks if an error is a ErrUsernameExists.
func IsErrUsernameExists(err error) bool {
	_, ok := err.(ErrUsernameExists)
	return ok
}

func (err ErrUsernameExists) Error() string {
	return fmt.Sprintf("a user with this username does already exist [user id: %d, username: %s]", err.UserID, err.Username)
}