how to wrap function to gin(c *gin.Context)

[awkj]

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• go version: go 1.12.4

• gin version (or commit ref): 1.3.0

• operating system: Mac/Linux

Description

My work function alway is signature

function(ctx context.Contex, req SomeStrcut) ( ret OtherStrcut,err error)

I wish to add a wrap function to wrap it, when err is nil I return

c.JSON(200, 
    gin.H{
      "code":err.Code,
      "msg":err.Error(),
      "data":nil,
     }

other return

c.JSON(200, 
    gin.H{
      "code":0,
      "msg":"",
      "data":ret,
     }

and , if gin must implement `func (c *gin.Context) to add router I try to write as

func Sum(ctx context.Context, req Req) (ret Resp, err error) {
    return
}

func Router() *gin.Engine {
    r := gin.Default()

    r.POST("/sum", func(c *gin.Context) {
        var req controller.Req
        err := c.ShouldBindJSON(&req)
        if err != nil && err != io.EOF {
            WriteJSON(c, nil, err)
            return
        }

        resp, err := controller.Sum(c.Request.Context(), req)
        WriteJSON(c, resp, err)
    })

    return r
}

func WriteJSON(c *gin.Context, resp interface{}, err error) {
    if err != nil {
        c.JSON(200, gin.H{
            "code":    400,
            "message": err.Error(),
            "data":    nil,
        })
    } else {
        c.JSON(200, gin.H{
            "code":    0,
            "message": "",
            "data":    resp,
        })
    }
}

but I must add this repeat code when I add a function, have better solution to write it ?

Screenshots

[erikbos]

Try

package main

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

func main() {
    r := gin.Default()
    r.POST("/status", wrapper(handler))
    r.Run(":8080")
}

func wrapper(f func(c *gin.Context) (string, error)) gin.HandlerFunc {

    return func(c *gin.Context) {
        _, err := f(c)
        if err != nil {
            c.JSON(503, gin.H{"status": err})
            return
        }
        c.JSON(200, gin.H{"status": "OK"})
    }
}

func handler(c *gin.Context) (string, error) {

    var status string
    if err := c.ShouldBindJSON(&status); err != nil {
        return "failed", err
    }
    return status, nil
}