How to validate headers and body in Gin-Gonic?

Question

I have a Gin program. When a request comes, I want all of the fields of the variable data (type ProductCreate) to have values: UserId (from headers) and Name, Price (from JSON body). I used the below code and it works:

package main

import (
    "fmt"
    "github.com/gin-gonic/gin"
)

type ProductCreate struct {
    UserId int    `header:"user-id"`
    Name   string `json:"name"`
    Price  int    `json:"price"`
}

func main() {
    r := gin.Default()

    r.POST("/product", func(c *gin.Context) {
        var data ProductCreate

        // bind the headers to data
        if err := c.ShouldBindHeader(&data); err != nil {
            c.JSON(400, err.Error())
            return
        }

        // bind the body to data
        if err := c.ShouldBindJSON(&data); err != nil {
            c.JSON(400, err.Error())
            return
        }

        c.JSON(200, data)
    })

    r.Run(":8080")
}

After that, I wanted to make sure that fields must be provided so I edited the ProductCreate struct like this:

type ProductCreate struct {
    UserId int    `header:"user-id" binding:"required"`
    Name   string `json:"name" binding:"required"`
    Price  int    `json:"price" binding:"required"`
}

Then it raised an unexpected error when I tested it again:

Key: 'ProductCreate.Name' Error:Field validation for 'Name' failed on the 'required' tag\nKey: 'ProductCreate.Price' Error:Field validation for 'Price' failed on the 'required' tag

I realized the error happened at this:

// bind the headers to data
if err := c.ShouldBindHeader(&data); err != nil {
   c.JSON(400, err.Error())
   return
}

Is there any solution to resolve my problem?

You can split the structure `ProductCreate`, one gets `UserId` use `ShouldBindHeader` to validate, other gets `Name` and `Price` use `ShouldBindJSON` to validate. Then combine them after validate. — spike014, Jul 22 '22 at 07:37

Srikanth Bhandary · Accepted Answer · 2022-07-22T09:49:22.553

Can you try this?

curl --location --request POST 'http://localhost:8080/product' \
--header 'user-id: 20' \
--data-raw '{
    "name": "sr"   
}'

I tried your code and it works perfectly.

{
    "UserId": 20,
    "name": "sr",
    "price": 0
}

Gin version: github.com/gin-gonic/gin v1.8.1 // indirect

Soln:

package main

import (
    "github.com/gin-gonic/gin"
)

type ProductCreate struct {
    Name  *string `json:"name" binding:"required"`
    Price *int    `json:"price" binding:"required"`
}

type Header struct {
    UserId *int `header:"user-id" binding:"required"`
}

func main() {
    r := gin.Default()

    r.POST("/product", func(c *gin.Context) {
        data := &ProductCreate{}
        header := &Header{}

        // bind the headers to data
        if err := c.ShouldBindHeader(header); err != nil {
            c.JSON(400, err.Error())
            return
        }

        // bind the body to data
        if err := c.ShouldBindJSON(data); err != nil {
            c.JSON(400, err.Error())
            return
        }

        c.JSON(200, data)
    })

    r.Run(":8080")
}

It can't. Please read again my question. There is a part I have edited ProductCreate struct (added binding:"required"`). — Ben Alpha, Jul 22 '22 at 09:28
@BenAlpha as so mentioned, I have split the header and body. This should work — Srikanth Bhandary, Jul 22 '22 at 09:50
Your solution is one of the solutions I considered. Actually, I have tried to find out a more concise and elegant solution that I think Gin has supported. Anyway, thanks for the effort. — Ben Alpha, Jul 22 '22 at 10:58

How to validate headers and body in Gin-Gonic?

1 Answers1