net/http: Request.ParseForm doesn't support PATCH requests

[mattetti]

HTTP PATCH requests are defined in this rfc: https://tools.ietf.org/html/rfc5789

The problem is that the current implementation for ParseForm is hardcoded to only parse
forms coming from POST or PUT requests, ignoring PATCH requests:

https://code.google.com/p/go/source/browse/src/pkg/net/http/request.go#731

The PostForm field should also be populated when making PATCH requests, from what I
could see, the underlying parsePostForm function wouldn't have an issue parsing a PATCH
request but we have a condition check that is preventing the parsing:

if r.Method == "POST" || r.Method == "PUT" {
    r.PostForm, err = parsePostForm(r)
}

I would gladly submit a patch but I have yet to understand the process to create a
codereview request.

[robfig]

Comment 1:

Discussion on golang-nuts
https://groups.google.com/d/msg/golang-nuts/GjngdEKsUXA/TIMHxkQkSp8J

[rsc]

Comment 2:

At the very least, as a workaround, you can change r.Method before calling ParseForm and
then change it back. I'd like to see real uses of PATCH before changing the standard
package.

Labels changed: added release-go1.4.

Status changed to Thinking.

[mattetti]

Comment 3:

Thanks for work around suggestion, it's probably better than adding a PUT route.
> I'd like to see real uses of PATCH before changing the standard package.
Certainly, at Splice we track music producer saves. The "saves" are stored as resources
and can be partially updated (set a description for instance) by sending a PATCH
request. A PUT request would not be appropriate since we only make a partial change to
the resource.
Would you like me to explain more in details? Or did I miss the point of your question?

[mattetti]

Comment 4:

I added a Code Review request with a fix: https://golang.org/cl/70990044 
(thanks @nathany for walking me through the process)

[bradfitz]

Comment 5:

Chatted with Russ. This is fine for now. I still want to clean a lot of this up and
maybe as part of that we'll just always call parsePostForm if that Content-Type is URL
encoded. But the test in this CL will prevent us from regressing in Go 1.4.

Labels changed: added release-go1.3, removed release-go1.4.

Status changed to Accepted.

[bradfitz]

Comment 6:

This issue was closed by revision b38320b.

Status changed to Fixed.