Golang Gotchas

HTTP Responses#

If you’ve a http.ResponseWriter object and using it to directly write the response to the connection, the order in which you write different parts of response is very important:

// First write headers.
wr.Header().Set("Content-Type", "text/plain; version=0.0.4")
// Then set the status code. And yes, this is the function name for setting status code!
wr.WriteHeader(http.StatusOK)
// Then finally write the response body.
wr.Write([]byte("hello world"))

NOTE

• Headers should be written first. If any extra header is set after calling WriteHeader it’s a no-op.
• Body should be after WriteHeader. Else it’s a no-op.