10 Handler
Lunny Xiao edited this page 7 years ago

Handler

Handler is the middleware of tango. In tango, almost everything will be Handler. Write your Handlers are easy.

type Handler interface {
    Handle(*tango.Context)
}

For example:

func MyHandler() tango.HandlerFunc {
    return func(ctx *tango.Context) {
        fmt.Println("this is my first tango handler")
        ctx.Next()
    }
}

t := tango.Classic()
t.Use(MyHandler())
t.Run()

Another form:

type HelloHandler struct {}

func (HelloHandler) Handle(ctx *tango.Context) {
    fmt.Println("before")
    ctx.Next()
    fmt.Println("after")
}

t := tango.Classic()
t.Use(new(HelloHandler))
t.Run()

Also, you can directly use a function as your handler:

tg.Use(func(ctx *tango.Context){
    fmt.Println("before")
    ctx.Next()
    fmt.Println("after")
})

For compitable, tango supports your old form handler via UseHandler()

tg.UseHandler(http.Handler(func(resp http.ResponseWriter, req *http.Request) {
     
}))

Old handler will be called before action invoked.

Call stack

When a request call by tango, below is the call stack:

tango.ServeHttp
|--Handler1
      |--Handler2
            |-- ...HandlerN
                      |---Action(If matched)
                ...HandlerN--|
         Handler2 ----|
   Handler1--|
(end)--|

In your Handler, all codes before ctx.Next() will be called before Action(If matched) will be called. All codes after ctx.Next() will be called after Action(If matched) called.

Of course, If your handler DO NOT call ctx.Next(). All call stack after will be not executed.