Fix #2206: Allow content-types "application/xxx+json" in ClientRespon…

…se.json() (#2819)

* Fix #2206: Allow content-types "application/xxx+json" in ClientResponse.json()

* Add test for custom content type; fix a bug in checking

CHANGES/2206.doc

@@ -0,0 +1 @@
+Change ```ClientResponse.json()``` documentation to reflect that it now allows "application/xxx+json" content-types

CHANGES/2206.feature

@@ -0,0 +1,2 @@
+Relax JSON content-type checking in the ``ClientResponse.json()`` to allow
+ "application/xxx+json" instead of strict "application/json".

aiohttp/client_reqrep.py

@@ -2,6 +2,7 @@
 import codecs
 import io
 import json
+import re
 import sys
 import traceback
 import warnings
@@ -39,6 +40,9 @@
 __all__ = ('ClientRequest', 'ClientResponse', 'RequestInfo', 'Fingerprint')
 
 
+json_re = re.compile('^application/(?:[\w.+-]+?\+)?json')
+
+
 @attr.s(frozen=True, slots=True)
 class ContentDisposition:
     type = attr.ib(type=str)
@@ -131,6 +135,12 @@ def _merge_ssl_params(ssl, verify_ssl, ssl_context, fingerprint):
 ConnectionKey = namedtuple('ConnectionKey', ['host', 'port', 'ssl'])
 
 
+def _is_expected_content_type(response_content_type, expected_content_type):
+    if expected_content_type == 'application/json':
+        return json_re.match(response_content_type)
+    return expected_content_type in response_content_type
+
+
 class ClientRequest:
     GET_METHODS = {
         hdrs.METH_GET,
@@ -859,7 +869,7 @@ async def json(self, *, encoding=None, loads=json.loads,
 
         if content_type:
             ctype = self.headers.get(hdrs.CONTENT_TYPE, '').lower()
-            if content_type not in ctype:
+            if not _is_expected_content_type(ctype, content_type):
                 raise ContentTypeError(
                     self.request_info,
                     self.history,

docs/client_advanced.rst

@@ -215,13 +215,18 @@ Disabling content type validation for JSON responses
 ----------------------------------------------------
 
 The standard explicitly restricts JSON ``Content-Type`` HTTP header to
-``apllication/json``. Unfortunately some servers send wrong type like
-``text/html`` or custom one, e.g. ``application/vnd.custom-type+json``.
+``application/json`` or any extended form, e.g. ``application/vnd.custom-type+json``.
+Unfortunately, some servers send a wrong type, like ``text/html``.
 
-In this case there are two options:
+This can be worked around in two ways:
 
-1. Pass expected type explicitly: ``await resp.json(content_type='custom')``.
-2. Disable the check entirely: ``await resp.json(content_type=None)``.
+1. Pass the expected type explicitly (in this case checking will be strict, without the extended form support,
+   so ``custom/xxx+type`` won't be accepted):
+
+   ``await resp.json(content_type='custom/type')``.
+2. Disable the check entirely:
+
+   ``await resp.json(content_type=None)``.
 
 .. _aiohttp-client-tracing:
 

tests/test_client_response.py

@@ -345,6 +345,45 @@ def side_effect(*args, **kwargs):
     assert response._connection is None
 
 
+async def test_json_extended_content_type(loop, session):
+    response = ClientResponse('get', URL('http://def-cl-resp.org'))
+    response._post_init(loop, session)
+
+    def side_effect(*args, **kwargs):
+        fut = loop.create_future()
+        fut.set_result('{"тест": "пройден"}'.encode('cp1251'))
+        return fut
+
+    response.headers = {
+        'Content-Type':
+            'application/this.is-1_content+subtype+json;charset=cp1251'}
+    content = response.content = mock.Mock()
+    content.read.side_effect = side_effect
+
+    res = await response.json()
+    assert res == {'тест': 'пройден'}
+    assert response._connection is None
+
+
+async def test_json_custom_content_type(loop, session):
+    response = ClientResponse('get', URL('http://def-cl-resp.org'))
+    response._post_init(loop, session)
+
+    def side_effect(*args, **kwargs):
+        fut = loop.create_future()
+        fut.set_result('{"тест": "пройден"}'.encode('cp1251'))
+        return fut
+
+    response.headers = {
+        'Content-Type': 'custom/type;charset=cp1251'}
+    content = response.content = mock.Mock()
+    content.read.side_effect = side_effect
+
+    res = await response.json(content_type='custom/type')
+    assert res == {'тест': 'пройден'}
+    assert response._connection is None
+
+
 async def test_json_custom_loader(loop, session):
     response = ClientResponse('get', URL('http://def-cl-resp.org'))
     response._post_init(loop, session)