Doc: State that Request.ParseForm() does not parse JSON payloads

[danieljsummers]

What did you expect to see?

I spent a good deal of time trying to determine why my XHR-style "forms" (actually JSON) were coming in blank.

What did you see instead?

After much debugging, head-desking, and searching, I discovered that this doesn't work that way. I've learned, but other people who have used other server frameworks may make the same mistake I did. In fact, I discovered it on Stack Overflow through someone else having the same problem.

I realize that a change to ParseForm would need to go through the language change proposal process. Obviously, nothing needs to be added to the language to be able to parse JSON payloads. However, I believe that a short note in this comment would help people understand that they'll need to parse JSON bodies themselves.

I'd be happy to update the comment to that effect, but before I go through that effort, I wanted to ask the team if that sort of thing would be welcome. So - let me know. :) (and thank you for your time)

[meirf]

The doc includes:

For other HTTP methods, or when the Content-Type is not application/x-www-form-urlencoded, the request Body is not read, and r.PostForm is initialized to a non-nil, empty value.

I assume your case is application/json.

Am I misunderstanding your case or maybe the doc does not spell out this lacking prominent enough for your liking?

[danieljsummers]

You're right that it does say that; I guess the negative implications of that statement didn't register with me.

I also probably ran down a rabbit trail because the router I was using at the time (Vestigo) puts its parameters in the form. I actually changed routers, thinking that Vestigo was whacking my posted values. Then, the form was always empty! :) (As one would expect, but that was the point where I got really confused.)

When I found the solution on Stack Overflow, I thought "Oh - of course." But, seeing the activity on that question, I thought it might be nice to call out this implication explicitly.

[meirf]

We generally want to keeps docs as succinct as possible since verbose docs leads to people ignoring them completely. Currently the doc is concise and correct on this matter.

It is staggering how popular that SO question is - 150k views. So maybe including something short about json being an example of unsupported content type could be helpful.

[pciet]

Which kind of HTTP method is your request? (https://tools.ietf.org/html/rfc2616#section-5.1.1)

[danieljsummers]

Mine was a POST, as was the one being discussed in the Stack Overflow thread.

[meirf]

@danieljsummers all things considered, I think you should close this issue and we should rely on current docs which seem ok.

[danieljsummers]

via PR, or without action?