How to use Middleware
This article mainly explains "how to use middleware". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's ideas to study and learn "how to use middleware".
Middle ware
Use the scene:
Auth authority authentication cross-domain other transactions that need to be processed before business processing
Let's continue with the last phase of the project.
Check the catalogue.
➜go-gin-test tree-L 3
.
├── go.mod
├── go.sum
├── hello
├── mian.go
└── routerex
└── router.go
Create a new mid directory under the routerex directory and a new mid.go file under the mid directory
First of all, we define a middleware. Its function is to verify whether the request is legal after the request arrives at the service, but before the business is processed.
Edit mid.go
Package mid
Import (
"github.com/gin-gonic/gin"
)
Func midAuth (c * gin.Context) {
/ / obtain the requested ip address
Ip: = c.ClientIP ()
/ / if the source of the request address is incorrect, prevent the request from continuing
If ip! = "baidu.com" {
Println ("incorrect ip address") c.Abort () return
}
/ / process the request
C.Next ()
}
Edit router.go
Package routerex
Import (
"example.com/m/v2/routerex/mid"
"github.com/gin-gonic/gin"
)
Func InitRouter (g * gin.Engine) {
G1: = g.Group ("G1")
/ / Middleware
G1.Use (mid.MidAuth)
G1.GET ("/ hello1", func (c * gin.Context) {
C.JSON (200, gin.H {
"msg": "Hello G1"
})
})
G2: = g.Group ("G2")
G2.GET ("/ hello2", func (c * gin.Context) {
C.JSON (200, gin.H {
"msg": "Hello G2"
})
})
}
Execute go build-o hello to compile to an executable file
➜go-gin-test go build-o hello
➜go-gin-test ls
Go.mod go.sum hello mian.go
Execute. / hello to get our service running
Open a browser to access http://localhost:8080/g1/hello1
Image.png [GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.
[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
-using env: export GIN_MODE=release
-using code: gin.SetMode (gin.ReleaseMode)
[GIN-debug] GET / g1/hello1-- > example.com/m/v2/routerex.InitRouter.func1 (4 handlers)
[GIN-debug] GET / g2/hello2-- > example.com/m/v2/routerex.InitRouter.func2 (3 handlers)
[GIN-debug] Environment variable PORT is undefined. Using port: 8080 by default
[GIN-debug] Listening and serving HTTP on: 8080
Incorrect ip address
[GIN] 2021-04-06-17:00:38 | 200 | 61.658 μ s |:: 1 | GET "/ g1/hello1"
You can see that there is no output on our browser.
But in the background log, we saw that the ip address we printed in the code was incorrect.
Through this way of thinking, we can achieve the requirements of many business or scenarios.
The following code is a general cross-domain middleware
Func midCors (c * gin.Context) {
C.Header ("Access-Control-Allow-Origin", c.Request.Header.Get ("Origin"))
C.Header ("Access-Control-Allow-Headers", "*")
C.Header ("Access-Control-Allow-Methods", "*")
C.Header ("Access-Control-Allow-Credentials", "true")
/ / release all OPTIONS methods
If c.Request.Method = = "OPTIONS" {
C.AbortWithStatus (http.StatusNoContent)
}
/ / process the request
C.Next ()
} how POST and GET get the value Parameters in path (url path parameter) name: = c.Param ("name") Querystring parameters// this word has a default value
Firstname: = c.DefaultQuery ("firstname", "Guest") Multipart/Urlencoded Form (form) / / No default value
Message: = c.PostForm ("message")
/ / have default value
Nick: = c.DefaultPostForm ("nick", "anonymous") Map as querystring or postform parameters (Map or form) ids: = c.QueryMap ("ids")
Names: = c.PostFormMap ("names") file (file type) form, _: = c.MultipartForm ()
Files: = form.File ["upload []"] JSON// structure
J: = J {}
C.BindJSON (j)
Of course, in addition to the common ways mentioned above, gin also provides a richer way to get parameters.
Thank you for your reading, the above is the content of "how to use middleware", after the study of this article, I believe you have a deeper understanding of how to use middleware, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!
