content_type not handled properly if it is a function

[bomb-on]

I have defined view decorator in my resource:

@view(renderer='json', content_type='application/json')

and when I call it without Content-Type properly defined, I get a 415 error.

However, if I want to call a function instead of defining a string for content_type

@view(renderer='json', content_type=content_type)

and in some other file i have defined that function:

def content_type(request):
    # interact with request
    return 'application/json'

it won't produce error 415, but it will return a 200 response.

Why is this happening? For some reason I'm sure it was working few months ago when I defined it in this way...

[leplatrem]

Why is this happening? For some reason I'm sure it was working few months ago when I defined it in this way...

I may be wrong, but I see nothing in the code base that would support providing content_type as a callable. That could be a relevant contribution IMO if you need it!

[bomb-on]

Hm, to be honest, I didn't go trough the code base, but I thought that this part of documentation is saying it is possible. Or is it only a service's feature?

[leplatrem]

OH! You are right, the documentation explicitly says it should work! That's a bug then! (either in code or documentation)

[amotl]

This should have worked, right. Have been there the other day (see #91) so will have a look if nobody is already into it.

[amotl]

Hey there, i had a look and found the following things:

• The documentation [1] is correct by stating

  The callable should return a list of accepted content types

  Here, @bomb-on tried to return a single internet media type as scalar, hence the misbehavior of Cornice

• However, when specifying the list of accepted content types as plain value, Cornice allows lists and scalars

To improve the functionality:

• Make content_type checks using callables capable of returning single internet media types as scalars, see properly handle content_type callables returning a single internet media type as scalar #350

[1] https://cornice.readthedocs.org/en/latest/validation.html#content-type-validation

Maybe consider relabeling this from "bug" to "enhancement".

[bomb-on]

Thanks for looking into this! I see you discussed it and changed the code base a bit, but just to check, does this mean that content_type can now accept functions?

[amotl]

@bomb-on: content_type always accepted functions, but the machinery was improved now to be able to cope with return values made of scalar strings. Before, it only accepted lists of media type strings but was poor on reporting that properly, so your use case failed somehow silently:

def content_type(request):
    # interact with request
    return 'application/json'

This should work now as we're using to_list(...) to always convert the callback return value to a list before propagating it internally.

[bomb-on]

@amotl ah, I understand now... Ok, thank you one more time guys for all the effort and keep up with good work ;)

[almet]

thanks for the kind words :)