Issue handling multiple types in one header

[tunnckoCore]

stated at helapkg/hela#22

Problem is that some API service - Alipay, sending request content-type header like that

application/x-www-form-urlencoded; text/html; charset=utf-8

I dont know why they send it like that, but there's no logic for me. We've tried in different ways, but didn't work.

is(req, ['x-www-form-urlencoded', 'html'])
is(req, ['application/x-www-form-urlencoded', 'text/html'])

It's not koa-better-body implementation issue, cuz it support extendTypes option that pass things to koa this.is/this.request.is

[tunnckoCore]

I think it would not be correct to support (if cant currently) thing like that and maybe we should pass the problem to Alipay tracker to fix their header?

[dougwilson]

Right, this module explicitly rejects that header value on purpose. The reason is that we detect if the type of a request is something; if the value in the content-type header is not a valid type, we're no longer comparing types, but rather random strings. In order to do intelligent type comparisons, like ignoring the parameters, we have to at least know it's actually a content-type header value.

There are really only two good courses of action here:

1. Get them to fix their header.
2. Re-write the header value before calling this module, either by altering the content-type header or calling is.is with the altered type (probably after calling is.hasBody).

[dougwilson]

You can also find some previous discussion on this exact Alipay issue in #12

[dougwilson]

It's also amusing to search Google for the string "application/x-www-form-urlencoded; text/html; charset=utf-8", as you see people using all kind of different language like Ruby, Java, C#, and more also having issues with Alipay's dumb header.

[dougwilson]

And for reference, you can find the exact format the Content-Type's value needs to be in at http://tools.ietf.org/html/rfc7231#section-3.1.1.5 . The issue with that header is that the second semicolon is an illegal character and no longer matches the RFC's ABNF expression for the Content-Type header.

[tunnckoCore]

Hm, okey. Just didn't have time to look at google.
So Alipay issue and we won't do anything, and with reason.

So @daiwhea, that's the way currently.

app.use(function * (next) {
  if (this.request.header['content-type'] === 'application/x-www-form-urlencoded; text/html; charset=utf-8') {
    this.request.header['content-type'] = 'application/x-www-form-urlencoded'
    // or 
    // this.request.header['content-type'] = 'application/x-www-form-urlencoded; charset=utf-8'
  }
  yield next
})

I'll think to do something on koa-better-body.

[dougwilson]

One option with koa-better-body is you could perhaps even take a function as the type to match, which is what I allow with the body-parser module (https://github.com/expressjs/body-parser#type).

If a function, the type option is called as fn(req) and the request is parsed if it returns a truthy value.