example to encode/decode gob in gin https://github.com/gin-gonic/gin/issues/1357

app.go

package main

import (
	"bytes"
	"encoding/gob"
	"net/http"

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

type foobar interface {
	Bar() string
}

type foo struct {
	FooBar foobar `json:"foobar" binding:"required"`
}

// foofoo satisfies foobar interface
type foofoo struct {
	BarBar string `json:"barbar"`
}

func (f *foofoo) Bar() string { return f.BarBar }

func init() {
	// this is needed for gob encoding/decoding
	gob.Register(&foofoo{})
}

func main() {
	r := gin.New()
	r.GET("/json", func(c *gin.Context) {
		ff := foofoo{BarBar: "bar string"}
		f := foo{FooBar: &ff}
		c.JSON(http.StatusOK, f)
	})
	r.POST("/json-post", func(c *gin.Context) {
		var f foo
		// this should fail because Go cannot know the real type from JSON string.
		if err := c.ShouldBindJSON(&f); err != nil {
			errJSON(c, err)
			return
		}
		c.JSON(http.StatusOK, f)
	})
	r.GET("/gob", func(c *gin.Context) {
		ff := foofoo{BarBar: "bar string"}
		f := foo{FooBar: &ff}
		out := bytes.NewBuffer(nil)
		if err := gob.NewEncoder(out).Encode(&f); err != nil {
			errJSON(c, err)
			return
		}
		c.Data(http.StatusOK, "application/x-gob", out.Bytes())
	})
	r.POST("/gob-post", func(c *gin.Context) {
		h, err := c.FormFile("file")
		if err != nil {
			errJSON(c, err)
			return
		}
		file, err := h.Open()
		if err != nil {
			errJSON(c, err)
			return
		}
		var f foo
		if err := gob.NewDecoder(file).Decode(&f); err != nil {
			errJSON(c, err)
			return
		}
		c.JSON(http.StatusOK, f)
	})
	r.Run(":8080")
}

func errJSON(c *gin.Context, err error) {
	c.AbortWithStatusJSON(
		http.StatusInternalServerError,
		gin.H{"err": err.Error()},
	)
}