Reading body of http.Request without modifying request state?

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Try reading into a buffer and then using the buffer to back two new readers, one for you to use, and one for subsequent consumers to use. For example, imagine that we want to modify the following code:

doStuff(r.Body) // r is an http.Request

We could do:

buf, _ := ioutil.ReadAll(r.Body)
rdr1 := ioutil.NopCloser(bytes.NewBuffer(buf))
rdr2 := ioutil.NopCloser(bytes.NewBuffer(buf))

doStuff(rdr1)
r.Body = rdr2 // OK since rdr2 implements the io.ReadCloser interface

// Now the program can continue oblivious to the fact that
// r.Body was ever touched.

Note that *bytes.Buffer does not have a Close() error method, so it doesn’t implement the io.ReadCloser interface. Thus, we have to wrap our *bytes.Buffer values in calls to ioutil.NopCloser.

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