Content-Length not set when using BodyJSON

[frankfil]

I have an API that I am making a POST call to with some data like the following code snippet:

// "object" is a struct
err := requests.URL("https://example.com/api/something").BodyJSON(object).Fetch(context.Background())

But the actual HTTP POST is missing the Content-Length Header, causing the server to respond with a 400 Bad Request (actually it probably should be 411 Length Required but that's a discussion I've yet to have with those devs).

The docs for NewRequestWithContext say the following:

If body is of type *bytes.Buffer, *bytes.Reader, or *strings.Reader, the returned request's ContentLength is set to its exact value (instead of -1), GetBody is populated (so 307 and 308 redirects can replay the body), and Body is set to NoBody if the ContentLength is 0.

A brief look at the BodyJSON func and it's returning an io.NopCloser so would I be correct in thinking this is why the Content-Length header is not being set?

So how can I get the header added with the correct value?

[earthboundkid]

The standard library is inconsistent about when it wants a Reader and when it wants a ReadCloser. I am adapting Readers into ReadClosers with io.NopCloser, but it looks like that is interfering with the Content Length setter. I think the fix is that I should write my own NopCloser type and just strip it off the body passed into NewRequestWithContext, but I’m not sure. I’ll poke around and see what I can figure out.

[earthboundkid]

See 184aed0. I'll take another look this afternoon to see if it can be merged in.

[earthboundkid]

I think 184aed0 should definitely go in, but another way to add a content length is with a custom transport:

func BufferedBodyTransport(rt http.RoundTripper) Transport {
	return RoundTripFunc(func(req *http.Request) (res *http.Response, err error) {
		var buf bytes.Buffer
		if _, err = io.Copy(&buf, req.Body); err != nil {
			return
		}
		// shallow copy req before modifying
		req2 := *req
		data := buf.Bytes()
		req2.Body = io.NopCloser(bytes.NewReader(data))
		req2.ContentLength = int64(len(data))
		req2.GetBody = func() (io.ReadCloser, error) {
			return io.NopCloser(bytes.NewReader(data)), nil
		}

		return rt.RoundTrip(&req2)
	})
}

Does that seem to have any other uses, or should people who need buffered bodies just save their data to a slice and use .BodyBytes?

[frankfil]

Your commit 184aed0 definitely solves the issue - thank you.

I can't think of a use for BufferedBodyTransport off the top of my head but others may find it useful. Even having this code to refer to as one method of modifying the transport is helpful.

[earthboundkid]

I made a wiki page and put it onto there: https://github.com/carlmjohnson/requests/wiki

[frankfil]

Tested your newly released tag and works perfectly - thank you!