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package main
import (
"net/http"
"reflect"
"github.com/gin-gonic/gin"
"github.com/gin-gonic/gin/binding"
validator "gopkg.in/go-playground/validator.v8"
)
// User contains user information.
type User struct {
FirstName string `json:"fname"`
LastName string `json:"lname"`
Email string `binding:"required,email"`
}
// UserStructLevelValidation contains custom struct level validations that don't always
// make sense at the field validation level. For example, this function validates that either
// FirstName or LastName exist; could have done that with a custom field validation but then
// would have had to add it to both fields duplicating the logic + overhead, this way it's
// only validated once.
//
// NOTE: you may ask why wouldn't not just do this outside of validator. Doing this way
// hooks right into validator and you can combine with validation tags and still have a
// common error output format.
func UserStructLevelValidation(v *validator.Validate, structLevel *validator.StructLevel) {
user := structLevel.CurrentStruct.Interface().(User)
if len(user.FirstName) == 0 && len(user.LastName) == 0 {
structLevel.ReportError(
reflect.ValueOf(user.FirstName), "FirstName", "fname", "fnameorlname",
)
structLevel.ReportError(
reflect.ValueOf(user.LastName), "LastName", "lname", "fnameorlname",
)
}
// plus can to more, even with different tag than "fnameorlname"
}
func main() {
route := gin.Default()
if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
v.RegisterStructValidation(UserStructLevelValidation, User{})
}
route.POST("/user", validateUser)
route.Run(":8085")
}
func validateUser(c *gin.Context) {
var u User
if err := c.ShouldBindJSON(&u); err == nil {
c.JSON(http.StatusOK, gin.H{"message": "User validation successful."})
} else {
c.JSON(http.StatusBadRequest, gin.H{
"message": "User validation failed!",
"error": err.Error(),
})
}
}
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