How to validate data from a middleware go-gin

Question

Trying to learn golang, and I am lost on working with the context.Request.Body and its struct in a validation middleware

briefly how do they connect to each other, thanks in advance for your help

My middleware

package validations

import (
    "github.com/bihire/ikaze_server_app/entity"
    "net/http"
    "github.com/gin-gonic/gin"
    "github.com/go-playground/validator/v10"
)


func SignupValidator(c *gin.Context) {
    // user := c.Request.Body
    var user entity.User
    validate := validator.New()
    if err := validate.Struct(&user); err != nil {
        c.JSON(http.StatusBadRequest, gin.H{
            "error": err.Error(),
        })
    }

}

My struct

package entity

type User struct {
    Username         string `json:"username" validate:"required"`
    Email            string `json:"email"  validate:"email"`
    Password         string `json:"password" validate:"min=8,max=32,alphanum"`
    ConfirmPassword  string `json:"confirm_password" validate:"eqfield=Password,required"`
}

returned response error

{
    "error": "Key: 'User.Username' Error:Field validation for 'Username' failed on the 'required' tag\nKey: 'User.Email' Error:Field validation for 'Email' failed on the 'email' tag\nKey: 'User.Password' Error:Field validation for 'Password' failed on the 'min' tag\nKey: 'User.ConfirmPassword' Error:Field validation for 'ConfirmPassword' failed on the 'required' tag"
}{
    "username": "bihire",
    "email": "hgh@gmail.com",
    "password": "password",
    "confirm_password": "password"
}

router with middleware

auth.POST("login", gin.Logger(), validations.SignupValidator, func(ctx *gin.Context) {
            ctx.JSON(200, videoController.Save(ctx))
        })

Answer 1

Looks like you're missing the return:

func SignupValidator(c *gin.Context) gin.HandlerFunc {
    return func(c *gin.Context) {
       var user entity.User
       if err := c.ShouldBindJSON(&user); err == nil {           
         validate := validator.New()
         if err := validate.Struct(&user); err != nil {
              c.JSON(http.StatusBadRequest, gin.H{
                 "error": err.Error(),
          })
          c.Abort()
          return
         }
       }
       c.Next()
    }
}

Note that we call c.Abort() if the validation failed. This is because gin calls the next function in the chain even after you write the header (c.JSON()) using c.Next().