Default charset does not apply to JSON responses

[href]

I've tested WebOb 1.7rc1 with Morepath and I've noticed that the default UTF-8 charset of the response only applies to text responses:

>>> from webob import Response
>>> Response("{}", content_type="text/plain")
<Response at 0x100f188d0 200 OK>
>>> Response("{}", content_type="application/json")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/denis/.virtualenvs/morepath/lib/python3.5/site-packages/webob/response.py", line 311, in __init__
    "You cannot set the body to a text value without a "
TypeError: You cannot set the body to a text value without a charset

Now I have no problem setting the charset of JSON responses explicitly (and as of today Morepath does), but I was wondering if this might be a bug.

I would have expected that the JSON response also uses the default charset defined on the Response class.

[ztane]

#196 and #197

[mmerickel]

It appears that default_body_encoding is not being used in the __init__. This is probably a bug. If you were doing response.text = "{}" things should work fine.

As far as the charset, you can see the linked issues from @ztane to understand that 1.7 explicitly changes this behavior in webob with regard to application/json.

[digitalresistor]

default_body_encoding is not used in in Response() on purpose. This is not a bug. Passing a body that is "text" is not supported if the Content-Type doesn't have a charset. Pass it as text instead

Like so:

>>> res = Response(text='{}', content_type='application/json') 
>>> res.body
b'{}'

When passing JSON, I would recommend:

>>> res = Response(json_body={}, content_type='application/json')
>>> res.body
b'{}'

Or

>>> res = Response(json_body={})
>>> res.content_type
'application/json'
>>> res.body
b'{}'

[digitalresistor]

Response("{}", content_type="text/plain")

Automatically adds the default charset:

>>> res = Response("{}", content_type="text/plain")
>>> res.headers['Content-Type']
'text/plain; charset=UTF-8'

Which allows you to set body to a "text" object to not break what has been allowed since WebOb 1.1. However I still fully believe that passing a body that is not a bytes object is something that might cause more issues than it is worth and it was disallowed explicitly on Content-Types that don't have a charset... so that things like this don't accidentally cause breakage:

Response('some text', content_type='image/jpeg')

I'd rather that raise an error than silently setting the body.

---

WebOb 1.6.x treats application/json as special, that special casing has been removed and it is now treated like all other non-text Content-Type's.

This meant there was inconsistent handling, for example:

>>> res = Response('{}', content_type='application/json')
>>> res.headers['Content-Type']
'application/json'
>>> res.text = '{}'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/~/python3.5/site-packages/webob/response.py", line 427, in _text__set
    "You cannot access Response.text unless charset is set")
AttributeError: You cannot access Response.text unless charset is set
>>>
>>> res = Response('test', content_type='image/jpeg')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/~/python3.5/site-packages/webob/response.py", line 139, in __init__
    "You cannot set the body to a text value without a "
TypeError: You cannot set the body to a text value without a charset

[href]

Ok I understand. Thanks for clearing this up for me - and sorry for missing the existing issues.

[digitalresistor]

I've documented this better in: http://docs.webob.org/en/1.7-branch/whatsnew-1.7.html#backwards-incompatibility as well documenting it in http://docs.webob.org/en/1.7-branch/api/response.html#webob.response.Response

Hopefully this will help other users that may run into the same issue.