$http is parsing a request to JSON ignoring the content-type

[jrivera294]

I'm submitting a ...

• bug report
• feature request
• other (Please do not submit support requests here (see above))

Current behavior:
The transformResponse is being executed based on a text/plain content, instead of the content-type headers, causing errors sometimes.

Expected / new behavior:
The transformResponse has to be called based on the content-type headers.

Minimal reproduction of the problem with instructions:
$http.get is trying parse to json a text/plain response (the content-type header from the server is "text/plain") when the text starts with "[" and ends with "]" characters.

Looking the documentation for baddata it says that it parses the body when the content-type header is application/json, and "the response looks like a valid JSON-stringified object or array".

And when I change the default transformResponse function to:
$http.get('/', { transformResponse: [function (data) { return data; }] })
To do nothing when it's called, the request works.

The $http request ignores the content-type response header and try to parse my response based in the body of the response?

Angular version: 1.6.2

Browser: all

Anything else:
I'm not sure how it detects that the body "looks like" a json to parse it automatically. But if the content-type of the response is "text/plain" it doesn't have to parse it, even if the body is a json object (not my case).

[Narretz]

Originally, AngularJS ignored the content type header completely and always tried to parse JSON: 7b6c1d0 This was changed to additionally always parse when the content-type header is set, and after that, only the json-likeness detection was updated.

Changing this would possibly break a lot of apps that simply don't set their content-type headers on the server correctly.

If you know that your response will always return text, you can detect this and skip the default transform, e.g. like this http://plnkr.co/edit/DgNEA1s62brfhVgsv6OL Or, if your API always returns text, remove the default http transform.

Note that the error you linked to is valid only from 1.6.4 onwards - before that you get a generic JSOn parse error.

But you are right that the error description is not correct about the workaround, because setting the header doesn't fix it.

[Narretz]

We could also employ some advanced heuristics to detect that this is not json, but this basically means we would have to parse the JSON. Pinging @gkalpak since he last worked on this code.

[jrivera294]

Question:

The responseType option shouldn't define the expected content-type?

And if that option doesn't do it, we can't add an option to set the expected content-type and don't try to parse to json?

Because even if we improve it with advanced heuristics, if we send a json object as text, or something that still appears to be a json we will have the same problem.

[Narretz]

Yes, this is the current status quo. Text that looks like json according to our detection will be parsed as such. We could add an option, but I don't know many devs would benefit from this, especially since there are workarounds.

[gkalpak]

At this point, I agree it is probably not worth addressing other than documenting the current behavior and work-around (as it could be a significant breaking change) 👍

[alexellis]

Hi folks,

I found this thread through Google and was not expecting the conclusion:

I agree it is probably not worth addressing

I think I'm seeing the same issue as described above but don't know how to get $http to stop parsing as JSON.

The HTTP call returns text/plain but the value looks similar to JSON (it is not JSON) and this breaks the page. I'm setting the request/response types to text but the success part of the promise never executes.. just the error part with a parsing error.

Please could you point me at the docs or workaround that I can use to prevent angular / $http from force-parsing text as if it were JSON? Related openfaas/faas#528

The plain-text value is: '[\n "foo" => "foo"\n]' and the content-type from the server is text/plain.

The code driving the page is here: https://github.com/openfaas/faas/blob/master/gateway/assets/script/bootstrap.js#L93

Thanks in advance for your help.