问题描述
这是一个后续问题,,因为那里的解决方案需要伪造一个请求,这对单元测试非常有用,但不适用于直播服务器。
我想转储HTTP响应,我的web服务响应它从用户接收到的请求而返回到日志文件(或控制台)中。输出应该告诉我头是什么和JSON有效载荷。
这是怎么回事?
如果有一个httputil.DumpResponse等价物将http.ResponseWriter作为参数而不是http.Response,那么这将是完美的,但目前我只能从http.ResponseWriter访问Header
r = mux.NewRouter()
r.HandleFunc(/ path,func(w http.ResponseWriter,r * http.Request){
fmt.Printf(r.HandleFunc / path \\\
)
resp:= server.NewResponse()
defer resp.Close()
r.ParseForm()
//服务器在这里做一些工作
// ...
//在这里插入调试代码,类似于
//
// dump = http.DumpResponseFromWriter(w)
// fmt.Printf(%s \ n,dump)
});
http.Handle(/ path,r)
中间件链接
这个问题的常见解决方案是所谓的中间件链。有几个库提供这种功能,例如。
这是一种延续形式,在这里写下你的中间件函数的样式(取自negroni的自述文件):
func MyMiddleware (rw http.ResponseWriter,r * http.Request,next http.HandlerFunc){
//在
next(rw,r)
之前做一些事情//在$ b之后做一些事
$ b
然后negroni为您提供一个HTTP处理程序,以正确的顺序调用您的中间件。 / p>
我们可以稍微不同的方式实现这个解决方案,这个方法的功能不如神奇功能更强大(如函数式编程)方法。定义处理程序组合子如下:
func NewFooHandler(next http.HandlerFunc)http.HandlerFunc {
return func(w http://ResponseWriter,r * http.Request){
//在
next(r,w)
之前做一些事情//在
之后做一些事情
}
然后将您的连锁店定义为一个组合:
h:= NewFooHandler(NewBarHandler(NewBazHandler(Sink)))
现在 h
是一个 http.HandlerFunc
,它会执行foo,然后是bar,然后是baz。 Sink
只是一个空的最后一个处理程序,它什么都不做(用来完成链接。)
应用这个解决您的问题
定义处理程序组合器:
func NewResponseLoggingHandler (下一个http.HandlerFunc)http.HandlerFunc {
返回func(w http.ResponseWriter,r * http.Request){
//转出记录器的响应编写器
//所有后续处理程序
c:= httptest.NewRecorder()
next(c,r)
//将所有内容从响应记录器
//复制到实际响应编写器
for k,v:= range c.HeaderMap {
w.Header()[k] = v
}
w.WriteHeader(c.Code)
c.Body.WriteTo(w)
}
}
现在问题归结为处理程序管理。您可能希望将此处理程序应用于某个类别的所有链。为此,您可以再次使用组合器(这与Negroni的 Classic()
方法)相当:
<$ p $
$ func NewDefaultHandler(next http.HandlerFunc)http.HandlerFunc {
return NewResponseLoggingHandler(NewOtherStuffHandler(next))
}
之后,每当你开始这样的连锁时:
h:= NewDefaultHandler(...)
它会自动包含响应记录和所有默认的东西你在 NewDefaultHandler
中定义的。
This is a follow-up question to In go, how to inspect the http response that is written to http.ResponseWriter? since the solution there requires faking a request, which works great for a unit test but not on a live server.
I would like to dump out HTTP response that my web service is returning in response to requests it receives from users into a log file (or to console). The output should tell me what the headers are and the JSON payload.
How does one go about that?
If there were a httputil.DumpResponse equivalent that takes a http.ResponseWriter as argument rather than http.Response it would be perfect, but currently I can only access the Header from http.ResponseWriter
r = mux.NewRouter()
r.HandleFunc("/path", func (w http.ResponseWriter, r *http.Request) {
fmt.Printf("r.HandleFunc /path\n")
resp := server.NewResponse()
defer resp.Close()
r.ParseForm()
// Server does some work here
// ...
// Insert debug code here, something like
//
// dump = http.DumpResponseFromWriter(w)
// fmt.Printf("%s\n", dump)
});
http.Handle("/path", r)
Middleware Chaining
A common solution to this problem is the so called middleware chain. There are several libraries that provide this functionality e.g. negroni.
It's a form of continuation-passing style where you write your middleware functions like this (taken from negroni's readme):
func MyMiddleware(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
// do some stuff before
next(rw, r)
// do some stuff after
}
And then negroni gives you an HTTP handler that calls your middlewares in the right order.
We could implement this solution slightly differently to a less magical and more functional (as in functional programming) approach. Define handler combinators as follows:
func NewFooHandler(next http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
// do some stuff before
next(r,w)
// do some stuff after
}
}
Then define your chain as a combination:
h := NewFooHandler(NewBarHandler(NewBazHandler(Sink)))
Now h
is an http.HandlerFunc
that does foo, then bar, then baz. Sink
is just an empty last handler, that does nothing (to "finish" the chain.)
Applying this solution to your problem
Define a handler combinator:
func NewResponseLoggingHandler(next http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
// switch out response writer for a recorder
// for all subsequent handlers
c := httptest.NewRecorder()
next(c, r)
// copy everything from response recorder
// to actual response writer
for k, v := range c.HeaderMap {
w.Header()[k] = v
}
w.WriteHeader(c.Code)
c.Body.WriteTo(w)
}
}
Now the problem boils down to handler management. You'll probably want this handler applied to all chains in a certain category. For this, you can use combinators again (this is somewhat equivalent to negroni's Classic()
method):
func NewDefaultHandler(next http.HandlerFunc) http.HandlerFunc {
return NewResponseLoggingHandler(NewOtherStuffHandler(next))
}
After this, whenever you start a chain like this:
h := NewDefaultHandler(...)
It will automatically include response logging and all the default stuff that you defined in NewDefaultHandler
.
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