Added Link header (RFC8288) parsing

CHANGES/2948.feature

@@ -0,0 +1 @@
+Added and links property for ClientResponse object

aiohttp/client_reqrep.py

@@ -687,6 +687,37 @@ def history(self):
         """A sequence of of responses, if redirects occurred."""
         return self._history
 
+    @property
+    def links(self):
+        links_str = ", ".join(self.headers.getall("link", []))
+
+        links = MultiDict()
+
+        if not links_str:
+            return MultiDictProxy(links)
+
+        for val in re.split(r",(?=\s*<)", links_str):
+            url, params = re.match(r"\s*<(.*)>(.*)", val).groups()
+            params = params.split(";")[1:]
+
+            link = MultiDict()
+
+            for param in params:
+                key, _, value, _ = re.match(
+                    r"^\s*(\S*)\s*=\s*(['\"]?)(.*?)(\2)\s*$",
+                    param, re.M
+                ).groups()
+
+                link.add(key, value)
+
+            key = link.get("rel", url)
+
+            link.add("url", self.url.join(URL(url)))
+
+            links.add(key, MultiDictProxy(link))
+
+        return MultiDictProxy(links)
+
     async def start(self, connection, read_until_eof=False):
         """Start response processing."""
         self._closed = False

docs/client_reference.rst

@@ -1097,6 +1097,16 @@ Response object
       Unmodified HTTP headers of response as unconverted bytes, a sequence of
       ``(key, value)`` pairs.
 
+   .. attribute:: links
+
+      Link HTTP header parsed into a :class:`~multidict.MultiDictProxy`.
+
+      For each link, key is link param `rel` when it exists, or link url as
+      :class:`str` otherwise, and value is :class:`~multidict.MultiDictProxy`
+      of link params and url at key `url` as :class:`~yarl.URL` instance.
+
+      .. versionadded:: 3.2
+
    .. attribute:: content_type
 
       Read-only property with *content* part of *Content-Type* header.

tests/test_client_response.py

@@ -6,6 +6,7 @@
 from unittest import mock
 
 import pytest
+from multidict import CIMultiDict
 from yarl import URL
 
 import aiohttp
@@ -1033,3 +1034,159 @@ def test_response_real_url(loop, session):
                               session=session)
     assert response.url == url.with_fragment(None)
     assert response.real_url == url
+
+
+def test_response_links_comma_separated(loop, session):
+    url = URL('http://def-cl-resp.org/')
+    response = ClientResponse('get', url,
+                              request_info=mock.Mock(),
+                              writer=mock.Mock(),
+                              continue100=None,
+                              timer=TimerNoop(),
+                              auto_decompress=True,
+                              traces=[],
+                              loop=loop,
+                              session=session)
+    response.headers = CIMultiDict([
+        (
+            "Link",
+            ('<http://example.com/page/1.html>; rel=next, '
+             '<http://example.com/>; rel=home')
+        )
+    ])
+    assert (
+        response.links ==
+        {'next':
+         {'url': URL('http://example.com/page/1.html'),
+          'rel': 'next'},
+         'home':
+         {'url': URL('http://example.com/'),
+          'rel': 'home'}
+         }
+    )
+
+
+def test_response_links_multiple_headers(loop, session):
+    url = URL('http://def-cl-resp.org/')
+    response = ClientResponse('get', url,
+                              request_info=mock.Mock(),
+                              writer=mock.Mock(),
+                              continue100=None,
+                              timer=TimerNoop(),
+                              auto_decompress=True,
+                              traces=[],
+                              loop=loop,
+                              session=session)
+    response.headers = CIMultiDict([
+        (
+            "Link",
+            '<http://example.com/page/1.html>; rel=next'
+        ),
+        (
+            "Link",
+            '<http://example.com/>; rel=home'
+        )
+    ])
+    assert (
+        response.links ==
+        {'next':
+         {'url': URL('http://example.com/page/1.html'),
+          'rel': 'next'},
+         'home':
+         {'url': URL('http://example.com/'),
+          'rel': 'home'}
+         }
+    )
+
+
+def test_response_links_no_rel(loop, session):
+    url = URL('http://def-cl-resp.org/')
+    response = ClientResponse('get', url,
+                              request_info=mock.Mock(),
+                              writer=mock.Mock(),
+                              continue100=None,
+                              timer=TimerNoop(),
+                              auto_decompress=True,
+                              traces=[],
+                              loop=loop,
+                              session=session)
+    response.headers = CIMultiDict([
+        (
+            "Link",
+            '<http://example.com/>'
+        )
+    ])
+    assert (
+        response.links ==
+        {
+            'http://example.com/':
+            {'url': URL('http://example.com/')}
+        }
+    )
+
+
+def test_response_links_quoted(loop, session):
+    url = URL('http://def-cl-resp.org/')
+    response = ClientResponse('get', url,
+                              request_info=mock.Mock(),
+                              writer=mock.Mock(),
+                              continue100=None,
+                              timer=TimerNoop(),
+                              auto_decompress=True,
+                              traces=[],
+                              loop=loop,
+                              session=session)
+    response.headers = CIMultiDict([
+        (
+            "Link",
+            '<http://example.com/>; rel="home-page"'
+        ),
+    ])
+    assert (
+        response.links ==
+        {'home-page':
+         {'url': URL('http://example.com/'),
+          'rel': 'home-page'}
+         }
+    )
+
+
+def test_response_links_relative(loop, session):
+    url = URL('http://def-cl-resp.org/')
+    response = ClientResponse('get', url,
+                              request_info=mock.Mock(),
+                              writer=mock.Mock(),
+                              continue100=None,
+                              timer=TimerNoop(),
+                              auto_decompress=True,
+                              traces=[],
+                              loop=loop,
+                              session=session)
+    response.headers = CIMultiDict([
+        (
+            "Link",
+            '</relative/path>; rel=rel'
+        ),
+    ])
+    assert (
+        response.links ==
+        {'rel':
+         {'url': URL('http://def-cl-resp.org/relative/path'),
+          'rel': 'rel'}
+         }
+    )
+
+
+def test_response_links_empty(loop, session):
+    url = URL('http://def-cl-resp.org/')
+    response = ClientResponse('get', url,
+                              request_info=mock.Mock(),
+                              writer=mock.Mock(),
+                              continue100=None,
+                              timer=TimerNoop(),
+                              auto_decompress=True,
+                              traces=[],
+                              loop=loop,
+                              session=session)
+    response.headers = CIMultiDict()
+    assert response.links == {}