Gin - part 2

November 11, 2019 Golang Gin

前言

繼續來玩gin囉~

Middleware

package main

import (
	"log"
	"net/http"

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

func main() {
	engine := gin.Default()
	engine.Any("/:name", middleware1, middleware2, middleware3, hello)
	engine.Run(":8081")
}

func hello(context *gin.Context) {
	name := context.Param("name")
	test := context.GetString("test")
	log.Printf("test: %s!", test)
	log.Printf("Hello %s!", name)
	context.String(http.StatusOK, "Hello %s!", name)
}

func middleware1(context *gin.Context) {
	buf := make([]byte, 1024)
	num, _ := context.Request.Body.Read(buf)
	log.Printf("middleware1: %s\n", string(buf[:num]))
	context.Next()
}

func middleware2(context *gin.Context) {
	log.Printf("middleware2: start")
	context.Next()
	log.Printf("middleware2: end")
}

func middleware3(context *gin.Context) {
	context.Set("test", "1234567890")
	context.Next()
}

output:

2019/11/12 23:43:49 middleware1: {
"hello": "world"
}
2019/11/12 23:43:49 middleware2: start
2019/11/12 23:43:49 test: 1234567890!
2019/11/12 23:43:49 Hello yooo!
2019/11/12 23:43:49 middleware2: end

middleware1他是將接收到的body資訊輸出到log中

func middleware1(context *gin.Context) {
	buf := make([]byte, 1024)
	num, _ := context.Request.Body.Read(buf)
	log.Printf("middleware1: %s\n", string(buf[:num]))
	context.Next()
}

middleware2他會先輸出middleware2: start後，等到後續都結束後，返回時才會輸出middleware2: end，比較django的middleware，context.Next()之前的就是request，之後的就是response

func middleware2(context *gin.Context) {
	log.Printf("middleware2: start")
	context.Next()
	log.Printf("middleware2: end")
}

middleware3在middlware中設新的值傳達到後續

func middleware3(context *gin.Context) {
	context.Set("test", "1234567890")
	context.Next()
}

middleware順序為:
進入: middleware1 -> middleware2 -> middleware3 -> hello
返回: hello -> middleware3 -> middleware2 -> middleware1

engine.Any("/:name", middleware1, middleware2, middleware3, hello)

區分middleware

剛剛的範例是專門給/:name這router在用的，假設我現在有個middleware想要所有router都使用，該怎麼做呢?

package main

import (
	"log"
	"net/http"

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

func main() {
	engine := gin.Default()
	engine.Use(middlewareGlobal)
	engine.Any("/demo", demo)
	engine.Any("/demo/:name", middleware1, middleware2, middleware3, hello)
	engine.Run(":8081")
}

func demo(context *gin.Context) {
	context.String(http.StatusOK, "demo")
}

func hello(context *gin.Context) {
	name := context.Param("name")
	test := context.GetString("test")
	log.Printf("test: %s!", test)
	log.Printf("Hello %s!", name)
	context.String(http.StatusOK, "Hello %s!", name)
}

func middlewareGlobal(context *gin.Context) {
	log.Printf("Global middleware")
	context.Next()
}

func middleware1(context *gin.Context) {
	buf := make([]byte, 1024)
	num, _ := context.Request.Body.Read(buf)
	log.Printf("middleware1: %s\n", string(buf[:num]))
	context.Next()
}

func middleware2(context *gin.Context) {
	log.Printf("middleware2: start")
	context.Next()
	log.Printf("middleware2: end")
}

func middleware3(context *gin.Context) {
	context.Set("test", "1234567890")
	context.Next()
}

output:

2019/11/12 23:57:40 Global middleware
2019/11/12 23:57:40 middleware1: {
"hello": "world"
}
2019/11/12 23:57:40 middleware2: start
2019/11/12 23:57:40 test: 1234567890!
2019/11/12 23:57:40 Hello yooooo!
2019/11/12 23:57:40 middleware2: end
[GIN] 2019/11/12 - 23:57:40 | 200 |     72.8047ms |       127.0.0.1 | POST     /demo/yooooo
2019/11/12 23:57:55 Global middleware
[GIN] 2019/11/12 - 23:57:55 | 200 |       997.3µs |       127.0.0.1 | GET      /demo

有時候可能出現api v1專用的middleware，比方說不同Version的api驗證方式不同的情況，可以怎麼做呢?

package main

import (
	"log"
	"net/http"

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

func main() {
	router := gin.Default()
	v1 := router.Group("/v1", apiV1middleware)
	{
		v1.GET("/welcome", welcomeV1)
	}
	v2 := router.Group("/v2")
	{
		v2.GET("/welcome", welcomeV2, apiV2middleware)
	}
	router.Run(":8081")
}

func welcomeV1(context *gin.Context) {
	context.String(http.StatusOK, "api v1 test")
}

func welcomeV2(context *gin.Context) {
	context.String(http.StatusOK, "api v2 test")
}

func apiV1middleware(context *gin.Context) {
	log.Printf("api v1 middlware")
}

func apiV2middleware(context *gin.Context) {
	log.Printf("api v2 middlware")
}

output:

2019/11/13 00:04:23 api v1 middlware
[GIN] 2019/11/13 - 00:04:23 | 200 |     71.8072ms |       127.0.0.1 | GET      /v1/welcome
2019/11/13 00:04:34 api v2 middlware
[GIN] 2019/11/13 - 00:04:34 | 200 |            0s |       127.0.0.1 | GET      /v2/welcome

Part2就先到這囉~~