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May 27, 2022 01:42
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Example of using a middleware with [httprouter](https://github.com/julienschmidt/httprouter)
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package main | |
import ( | |
"fmt" | |
"github.com/julienschmidt/httprouter" | |
"log" | |
"net/http" | |
) | |
// The type of our middleware consists of the original handler we want to wrap and a message | |
type Middleware struct { | |
next http.Handler | |
message string | |
} | |
// Make a constructor for our middleware type since its fields are not exported (in lowercase) | |
func NewMiddleware(next http.Handler, message string) *Middleware { | |
return &Middleware{next: next, message: message} | |
} | |
// Our middleware handler | |
func (m *Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request) { | |
// We can modify the request here; for simplicity, we will just log a message | |
log.Printf("msg: %s, Method: %s, URI: %s\n", m.message, r.Method, r.RequestURI) | |
m.next.ServeHTTP(w, r) | |
// We can modify the response here | |
} | |
// Our handle function | |
func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) { | |
fmt.Fprint(w, "Welcome!\n") | |
} | |
func main() { | |
router := httprouter.New() | |
router.GET("/", Index) | |
m := NewMiddleware(router, "I'm a middleware") | |
log.Fatal(http.ListenAndServe(":3000", m)) | |
} |
A very simple and straightforward example. Just what was after. Thank you.
I'm confused about line 22. How are you able to call func (variables) returnType { ... } without a function name? essentially, why didn't you write func middleHandler(variables) returnType { ... }? Thank you
I'm confused about line 22. How are you able to call func (variables) returnType { ... } without a function name? essentially, why didn't you write func middleHandler(variables) returnType { ... }? Thank you
func (m *Middleware) ServeHTTP(w http.ResponseWriter, r *http.Request)
(m *Middleware) means that this function belongs to this type
ServeHTTP is the name of the function
w and r are parameters, both of them postceded by their types.
thank you !
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Nice example, I think it will be more helpful if you add middleware2 and chain it with first middleware.