02-Gin request parameters

One: request and request binding

1.1: Path parameters

• : Parameter name, means to take the middle part.
• *Parameter name, means all the data after fetching.
• Path parameters, obtained with context.Param().
• case:

package animal

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

func Routers(e *gin.Engine) {
    
    
	e.GET("/animal/:name/*action", testArgs)
}

package animal

import (
	"github.com/gin-gonic/gin"
	"net/http"
	"strings"
)

func testArgs(context *gin.Context) {
    
    
	// 请求：http://127.0.0.1:8080/animal/dog/jiao/wangwang
	name := context.Param("name")          // dog
	action := context.Param("action")      // /jiao/wangwang
	action = strings.Split(action, "/")[2] // wangwang
	context.String(http.StatusOK, "name is %s, action is %s", name, action)
}

1.2: Query String Parameters

• DefaultQuery() returns the default value if the parameter does not exist, and returns an empty string if Query() does not exist.
• DefaultQuery() case:

package animal

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

func Routers(e *gin.Engine) {
    
    
	e.GET("/animal/login", testArgs)
}

package animal

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

func testArgs(context *gin.Context) {
    
    
	// 请求： http://127.0.0.1:8080/animal/login?name=dog&password=1234567890
	name := context.DefaultQuery("name", "root")
	password := context.DefaultQuery("password", "123456")
	context.String(http.StatusOK, "name is %s, password is %s。", name, password)
}

• Query() case

package animal

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

func testArgs(context *gin.Context) {
    
    
	// 请求： http://127.0.0.1:8080/animal/login?name=dog&password=1234567890
	name := context.Query("name")
	password := context.Query("password")
	if name == "" || password == "" {
    
    
		context.String(http.StatusOK, "必要参数缺失")
	} else {
    
    
		context.String(http.StatusOK, "name is %s, password is %s。", name, password)
	}
}

1.3: Form parameters

• PostForm() can parse form parameters

func testArgs(context *gin.Context) {
    
    
	// 请求：multipart/form-data
	name := context.PostForm("name")
	password := context.PostForm("password")
	if name == "" || password == "" {
    
    
		context.String(http.StatusOK, "必要参数缺失")
	} else {
    
    
		context.String(http.StatusOK, "name is %s, password is %s。", name, password)
	}
}

• Form to upload files

package animal

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

func testArgs(context *gin.Context) {
    
    
	// 请求：multipart/form-data
	file, err := context.FormFile("file")
	if err != nil {
    
    
		context.String(500, "file upload fail, err msg is %s", err)
		return
	}
	err = context.SaveUploadedFile(file, file.Filename)
	if err != nil {
    
    
		context.String(500, "file save fail, err msg is %s", err)
		return
	}
	context.String(http.StatusOK, file.Filename)
}

1.4: JSON data

• The parameters are bound to the structure: context.ShouldBindJSON()
• Note: First, you need to instantiate a structure object, and then pass in the reference of the structure object.
• Why must the address be passed?
  • Because instantiated objects must be modified. If the essence of passing an object is to copy a new one, it will not change the current object.

package animal

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

type LoginJsonArgs struct {
    
    
	Name     string `json:"name" binding:"required"`
	Password string `json:"password" binding:"required"`
}

func testArgs(context *gin.Context) {
    
    
	// 请求：JSON数据
	// 获取JSON参数并绑定参数
	var loginArgs LoginJsonArgs
	err := context.ShouldBindJSON(&loginArgs)
	if err != nil {
    
    
		context.JSON(http.StatusBadRequest, gin.H{
    
    "error": err.Error()})
		return
	}
	// 校验参数
	if loginArgs.Name != "root" && loginArgs.Password != "123456" {
    
    
		context.JSON(http.StatusUnauthorized, gin.H{
    
    "status": "401", "msg": "args validated fail"})
	} else {
    
    
		context.JSON(http.StatusOK, gin.H{
    
    "status": "200", "msg": "login success"})
	}
}

1.5: Forms can also bind structures

• Restrict form binding in structure

type LoginJsonArgs struct {
    
    
	Name     string `form:"name" binding:"required"`
	Password string `form:"password" binding:"required"`
}

• The bound function uses Bind()

	var loginArgs LoginJsonArgs
	err := context.Bind(&loginArgs)
	if err != nil {
    
    
		context.JSON(http.StatusBadRequest, gin.H{
    
    "error": err.Error()})
		return
	}

1.6: Path parameter binding

• Struct Limit Binding

type LoginJsonArgs struct {
    
    
	Name     string `uri:"name" binding:"required"`
	Password string `uri:"password" binding:"required"`
}

• The bind function takes ShouldBindUri()

	var loginArgs LoginJsonArgs
	err := context.ShouldBindUri(&loginArgs)
	if err != nil {
    
    
		context.JSON(http.StatusBadRequest, gin.H{
    
    "error": err.Error()})
		return
	}

• modify route

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

func Routers(e *gin.Engine) {
    
    
	e.GET("/animal/login/:name/:password", testArgs)
}

1.7: Query string binding

• The structure restricts the binding parameters: the same as the Form form.

type LoginJsonArgs struct {
    
    
	Name     string `form:"name" binding:"required"`
	Password string `form:"password" binding:"required"`
}

• Modify the binding method

	var loginArgs LoginJsonArgs
	err := context.ShouldBindQuery(&loginArgs)
	if err != nil {
    
    
		context.JSON(http.StatusBadRequest, gin.H{
    
    "error": err.Error()})
		return
	}

1.8: Binding Header

• Structure limit request header parameters

type LoginJsonArgs struct {
    
    
	Name     string `header:"name" binding:"required"`
	Password string `header:"password" binding:"required"`
}

• Modify binding parameters

	var loginArgs LoginJsonArgs
	err := context.ShouldBindHeader(&loginArgs)
	if err != nil {
    
    
		context.JSON(http.StatusBadRequest, gin.H{
    
    "error": err.Error()})
		return
	}

1.9: Use the Bind or ShouldBind method?

• Difference: If Bind fails to bind, it will automatically add 400 status code information to the response header.
• It is recommended to use ShouldBind to let the front end judge based on the returned response information instead of using the status code of the response header.

Two: Response

2.1: Return JSON data

context.JSON(http.StatusOK, gin.H{
    
    "status": "200", "msg": "login success"})

2.2: return structure

• The essence is to convert it into JSON and return it

package animal

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

type LoginJsonArgs struct {
    
    
	Name     string `form:"name" binding:"required"`
	Password string `form:"password" binding:"required"`
}

func testArgs(context *gin.Context) {
    
    
	// 绑定Header
	var loginArgs LoginJsonArgs
	err := context.ShouldBindQuery(&loginArgs)
	if err != nil {
    
    
		context.JSON(http.StatusBadRequest, gin.H{
    
    "error": err.Error()})
		return
	}
	// 校验参数
	if loginArgs.Name != "root" && loginArgs.Password != "123456" {
    
    
		context.JSON(http.StatusUnauthorized, gin.H{
    
    "status": "401", "msg": "args validated fail"})
	} else {
    
    
		context.JSON(http.StatusOK, loginArgs)
	}
}

2.3: Return to protobuf

		// 自定义PB格式
		reps := []int64{
    
    int64(1), int64(2)}
		label := "resData"
		resData := &protoexample.Test{
    
    
			Label: &label,
			Reps:  reps,
		}
		context.ProtoBuf(200, resData)

2.4: Return redirection

 context.Redirect(http.StatusMovedPermanently, "XXX地址")

Three: asynchronous context

• In an asynchronous request, if the context is to be used, the context must be copied again.

package main

import (
    "log"
    "time"

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

func main() {
    
    
    r := gin.Default()
    // 1.异步
    r.GET("/long_async", func(c *gin.Context) {
    
    
        // 需要搞一个副本
        copyContext := c.Copy()
        // 异步处理
        go func() {
    
    
            time.Sleep(3 * time.Second)
            log.Println("异步执行：" + copyContext.Request.URL.Path)
        }()
    })
    r.Run(":8000")
}