Fix up preview URL API. Add tests.
This includes: - Splitting out methods of a class into stand alone functions, to make them easier to test. - Adding unit tests to split out functions, testing HTML -> preview. - Handle the fact that elements in lxml may have tail text.
This commit is contained in:
Erik Johnston
parent
7c6f4f9427
commit
48b5829aea
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@ -163,7 +163,7 @@ class PreviewUrlResource(Resource):
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logger.debug("got media_info of '%s'" % media_info)
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if self._is_media(media_info['media_type']):
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if _is_media(media_info['media_type']):
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dims = yield self.media_repo._generate_local_thumbnails(
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media_info['filesystem_id'], media_info
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)
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@ -184,11 +184,9 @@ class PreviewUrlResource(Resource):
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logger.warn("Couldn't get dims for %s" % url)
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# define our OG response for this media
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elif self._is_html(media_info['media_type']):
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elif _is_html(media_info['media_type']):
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# TODO: somehow stop a big HTML tree from exploding synapse's RAM
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from lxml import etree
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file = open(media_info['filename'])
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body = file.read()
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file.close()
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@ -199,17 +197,35 @@ class PreviewUrlResource(Resource):
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match = re.match(r'.*; *charset=(.*?)(;|$)', media_info['media_type'], re.I)
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encoding = match.group(1) if match else "utf-8"
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try:
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parser = etree.HTMLParser(recover=True, encoding=encoding)
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tree = etree.fromstring(body, parser)
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og = yield self._calc_og(tree, media_info, requester)
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except UnicodeDecodeError:
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# blindly try decoding the body as utf-8, which seems to fix
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# the charset mismatches on https://google.com
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parser = etree.HTMLParser(recover=True, encoding=encoding)
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tree = etree.fromstring(body.decode('utf-8', 'ignore'), parser)
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og = yield self._calc_og(tree, media_info, requester)
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og = decode_and_calc_og(body, media_info['uri'], encoding)
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# pre-cache the image for posterity
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# FIXME: it might be cleaner to use the same flow as the main /preview_url
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# request itself and benefit from the same caching etc. But for now we
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# just rely on the caching on the master request to speed things up.
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if 'og:image' in og and og['og:image']:
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image_info = yield self._download_url(
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_rebase_url(og['og:image'], media_info['uri']), requester.user
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)
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if _is_media(image_info['media_type']):
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# TODO: make sure we don't choke on white-on-transparent images
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dims = yield self.media_repo._generate_local_thumbnails(
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image_info['filesystem_id'], image_info
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)
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if dims:
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og["og:image:width"] = dims['width']
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og["og:image:height"] = dims['height']
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else:
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logger.warn("Couldn't get dims for %s" % og["og:image"])
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og["og:image"] = "mxc://%s/%s" % (
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self.server_name, image_info['filesystem_id']
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)
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og["og:image:type"] = image_info['media_type']
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og["matrix:image:size"] = image_info['media_length']
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else:
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del og["og:image"]
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else:
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logger.warn("Failed to find any OG data in %s", url)
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og = {}
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@ -232,139 +248,6 @@ class PreviewUrlResource(Resource):
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respond_with_json_bytes(request, 200, json.dumps(og), send_cors=True)
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@defer.inlineCallbacks
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def _calc_og(self, tree, media_info, requester):
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# suck our tree into lxml and define our OG response.
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# if we see any image URLs in the OG response, then spider them
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# (although the client could choose to do this by asking for previews of those
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# URLs to avoid DoSing the server)
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# "og:type" : "video",
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# "og:url" : "https://www.youtube.com/watch?v=LXDBoHyjmtw",
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# "og:site_name" : "YouTube",
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# "og:video:type" : "application/x-shockwave-flash",
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# "og:description" : "Fun stuff happening here",
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# "og:title" : "RemoteJam - Matrix team hack for Disrupt Europe Hackathon",
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# "og:image" : "https://i.ytimg.com/vi/LXDBoHyjmtw/maxresdefault.jpg",
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# "og:video:url" : "http://www.youtube.com/v/LXDBoHyjmtw?version=3&autohide=1",
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# "og:video:width" : "1280"
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# "og:video:height" : "720",
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# "og:video:secure_url": "https://www.youtube.com/v/LXDBoHyjmtw?version=3",
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og = {}
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for tag in tree.xpath("//*/meta[starts-with(@property, 'og:')]"):
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if 'content' in tag.attrib:
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og[tag.attrib['property']] = tag.attrib['content']
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# TODO: grab article: meta tags too, e.g.:
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# "article:publisher" : "https://www.facebook.com/thethudonline" />
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# "article:author" content="https://www.facebook.com/thethudonline" />
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# "article:tag" content="baby" />
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# "article:section" content="Breaking News" />
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# "article:published_time" content="2016-03-31T19:58:24+00:00" />
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# "article:modified_time" content="2016-04-01T18:31:53+00:00" />
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if 'og:title' not in og:
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# do some basic spidering of the HTML
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title = tree.xpath("(//title)[1] | (//h1)[1] | (//h2)[1] | (//h3)[1]")
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og['og:title'] = title[0].text.strip() if title else None
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if 'og:image' not in og:
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# TODO: extract a favicon failing all else
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meta_image = tree.xpath(
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"//*/meta[translate(@itemprop, 'IMAGE', 'image')='image']/@content"
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)
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if meta_image:
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og['og:image'] = self._rebase_url(meta_image[0], media_info['uri'])
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else:
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# TODO: consider inlined CSS styles as well as width & height attribs
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images = tree.xpath("//img[@src][number(@width)>10][number(@height)>10]")
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images = sorted(images, key=lambda i: (
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-1 * float(i.attrib['width']) * float(i.attrib['height'])
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))
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if not images:
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images = tree.xpath("//img[@src]")
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if images:
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og['og:image'] = images[0].attrib['src']
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# pre-cache the image for posterity
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# FIXME: it might be cleaner to use the same flow as the main /preview_url
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# request itself and benefit from the same caching etc. But for now we
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# just rely on the caching on the master request to speed things up.
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if 'og:image' in og and og['og:image']:
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image_info = yield self._download_url(
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self._rebase_url(og['og:image'], media_info['uri']), requester.user
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)
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if self._is_media(image_info['media_type']):
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# TODO: make sure we don't choke on white-on-transparent images
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dims = yield self.media_repo._generate_local_thumbnails(
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image_info['filesystem_id'], image_info
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)
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if dims:
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og["og:image:width"] = dims['width']
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og["og:image:height"] = dims['height']
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else:
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logger.warn("Couldn't get dims for %s" % og["og:image"])
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og["og:image"] = "mxc://%s/%s" % (
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self.server_name, image_info['filesystem_id']
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)
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og["og:image:type"] = image_info['media_type']
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og["matrix:image:size"] = image_info['media_length']
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else:
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del og["og:image"]
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if 'og:description' not in og:
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meta_description = tree.xpath(
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"//*/meta"
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"[translate(@name, 'DESCRIPTION', 'description')='description']"
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"/@content")
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if meta_description:
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og['og:description'] = meta_description[0]
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else:
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# grab any text nodes which are inside the <body/> tag...
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# unless they are within an HTML5 semantic markup tag...
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# <header/>, <nav/>, <aside/>, <footer/>
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# ...or if they are within a <script/> or <style/> tag.
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# This is a very very very coarse approximation to a plain text
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# render of the page.
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# We don't just use XPATH here as that is slow on some machines.
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# We clone `tree` as we modify it.
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cloned_tree = deepcopy(tree.find("body"))
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TAGS_TO_REMOVE = ("header", "nav", "aside", "footer", "script", "style",)
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for el in cloned_tree.iter(TAGS_TO_REMOVE):
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el.getparent().remove(el)
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# Split all the text nodes into paragraphs (by splitting on new
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# lines)
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text_nodes = (
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re.sub(r'\s+', '\n', el.text).strip()
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for el in cloned_tree.iter()
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if el.text and isinstance(el.tag, basestring) # Removes comments
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)
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og['og:description'] = summarize_paragraphs(text_nodes)
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# TODO: delete the url downloads to stop diskfilling,
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# as we only ever cared about its OG
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defer.returnValue(og)
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def _rebase_url(self, url, base):
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base = list(urlparse.urlparse(base))
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url = list(urlparse.urlparse(url))
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if not url[0]: # fix up schema
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url[0] = base[0] or "http"
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if not url[1]: # fix up hostname
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url[1] = base[1]
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if not url[2].startswith('/'):
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url[2] = re.sub(r'/[^/]+$', '/', base[2]) + url[2]
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return urlparse.urlunparse(url)
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@defer.inlineCallbacks
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def _download_url(self, url, user):
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# TODO: we should probably honour robots.txt... except in practice
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@ -445,17 +328,173 @@ class PreviewUrlResource(Resource):
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"etag": headers["ETag"][0] if "ETag" in headers else None,
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})
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def _is_media(self, content_type):
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if content_type.lower().startswith("image/"):
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return True
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def _is_html(self, content_type):
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content_type = content_type.lower()
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if (
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content_type.startswith("text/html") or
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content_type.startswith("application/xhtml")
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):
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return True
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def decode_and_calc_og(body, media_uri, request_encoding=None):
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from lxml import etree
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try:
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parser = etree.HTMLParser(recover=True, encoding=request_encoding)
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tree = etree.fromstring(body, parser)
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og = _calc_og(tree, media_uri)
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except UnicodeDecodeError:
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# blindly try decoding the body as utf-8, which seems to fix
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# the charset mismatches on https://google.com
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parser = etree.HTMLParser(recover=True, encoding=request_encoding)
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tree = etree.fromstring(body.decode('utf-8', 'ignore'), parser)
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og = _calc_og(tree, media_uri)
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return og
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def _calc_og(tree, media_uri):
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# suck our tree into lxml and define our OG response.
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# if we see any image URLs in the OG response, then spider them
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# (although the client could choose to do this by asking for previews of those
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# URLs to avoid DoSing the server)
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# "og:type" : "video",
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# "og:url" : "https://www.youtube.com/watch?v=LXDBoHyjmtw",
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# "og:site_name" : "YouTube",
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# "og:video:type" : "application/x-shockwave-flash",
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# "og:description" : "Fun stuff happening here",
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# "og:title" : "RemoteJam - Matrix team hack for Disrupt Europe Hackathon",
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# "og:image" : "https://i.ytimg.com/vi/LXDBoHyjmtw/maxresdefault.jpg",
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# "og:video:url" : "http://www.youtube.com/v/LXDBoHyjmtw?version=3&autohide=1",
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# "og:video:width" : "1280"
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# "og:video:height" : "720",
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# "og:video:secure_url": "https://www.youtube.com/v/LXDBoHyjmtw?version=3",
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og = {}
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for tag in tree.xpath("//*/meta[starts-with(@property, 'og:')]"):
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if 'content' in tag.attrib:
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og[tag.attrib['property']] = tag.attrib['content']
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# TODO: grab article: meta tags too, e.g.:
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# "article:publisher" : "https://www.facebook.com/thethudonline" />
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# "article:author" content="https://www.facebook.com/thethudonline" />
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# "article:tag" content="baby" />
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# "article:section" content="Breaking News" />
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# "article:published_time" content="2016-03-31T19:58:24+00:00" />
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# "article:modified_time" content="2016-04-01T18:31:53+00:00" />
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if 'og:title' not in og:
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# do some basic spidering of the HTML
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title = tree.xpath("(//title)[1] | (//h1)[1] | (//h2)[1] | (//h3)[1]")
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og['og:title'] = title[0].text.strip() if title else None
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if 'og:image' not in og:
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# TODO: extract a favicon failing all else
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meta_image = tree.xpath(
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"//*/meta[translate(@itemprop, 'IMAGE', 'image')='image']/@content"
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)
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if meta_image:
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og['og:image'] = _rebase_url(meta_image[0], media_uri)
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else:
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# TODO: consider inlined CSS styles as well as width & height attribs
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images = tree.xpath("//img[@src][number(@width)>10][number(@height)>10]")
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images = sorted(images, key=lambda i: (
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-1 * float(i.attrib['width']) * float(i.attrib['height'])
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))
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if not images:
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images = tree.xpath("//img[@src]")
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if images:
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og['og:image'] = images[0].attrib['src']
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if 'og:description' not in og:
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meta_description = tree.xpath(
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"//*/meta"
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"[translate(@name, 'DESCRIPTION', 'description')='description']"
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"/@content")
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if meta_description:
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og['og:description'] = meta_description[0]
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else:
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# grab any text nodes which are inside the <body/> tag...
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# unless they are within an HTML5 semantic markup tag...
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# <header/>, <nav/>, <aside/>, <footer/>
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# ...or if they are within a <script/> or <style/> tag.
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# This is a very very very coarse approximation to a plain text
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# render of the page.
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# We don't just use XPATH here as that is slow on some machines.
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from lxml import etree
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TAGS_TO_REMOVE = (
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"header", "nav", "aside", "footer", "script", "style", etree.Comment
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)
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# Split all the text nodes into paragraphs (by splitting on new
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# lines)
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text_nodes = (
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re.sub(r'\s+', '\n', el).strip()
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for el in _iterate_over_text(tree.find("body"), *TAGS_TO_REMOVE)
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)
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og['og:description'] = summarize_paragraphs(text_nodes)
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# TODO: delete the url downloads to stop diskfilling,
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# as we only ever cared about its OG
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return og
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def _iterate_over_text(tree, *tags_to_ignore):
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"""Iterate over the tree returning text nodes in a depth first fashion,
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skipping text nodes inside certain tags.
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"""
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import itertools
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# This is basically a stack that we extend using itertools.chain.
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# This will either consist of an element to iterate over *or* a string
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# to be returned.
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elements = iter([tree])
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while True:
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el = elements.next()
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if isinstance(el, basestring):
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yield el
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elif el.tag not in tags_to_ignore:
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# el.text is the text before the first child, so we can immediately
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# return it if the text exists.
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if el.text:
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yield el.text
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# We add to the stack all the elements children, interspersed with
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# each child's tail text (if it exists). The tail text of a node
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# is text that comes *after* the node, so we always include it even
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# if we ignore the child node.
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elements = itertools.chain(
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itertools.chain.from_iterable( # Basically a flatmap
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[child, child.tail] if child.tail else [child]
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for child in el.iterchildren()
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),
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elements
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)
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def _rebase_url(url, base):
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base = list(urlparse.urlparse(base))
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url = list(urlparse.urlparse(url))
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if not url[0]: # fix up schema
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url[0] = base[0] or "http"
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if not url[1]: # fix up hostname
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url[1] = base[1]
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if not url[2].startswith('/'):
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url[2] = re.sub(r'/[^/]+$', '/', base[2]) + url[2]
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return urlparse.urlunparse(url)
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def _is_media(content_type):
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if content_type.lower().startswith("image/"):
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return True
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def _is_html(content_type):
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content_type = content_type.lower()
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if (
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content_type.startswith("text/html") or
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content_type.startswith("application/xhtml")
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):
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return True
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def summarize_paragraphs(text_nodes, min_size=200, max_size=500):
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@ -15,7 +15,9 @@
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from . import unittest
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from synapse.rest.media.v1.preview_url_resource import summarize_paragraphs
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from synapse.rest.media.v1.preview_url_resource import (
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summarize_paragraphs, decode_and_calc_og
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)
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class PreviewTestCase(unittest.TestCase):
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@ -137,3 +139,79 @@ class PreviewTestCase(unittest.TestCase):
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" of old wooden houses in Northern Norway, the oldest house dating from"
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" 1789. The Arctic Cathedral, a modern church…"
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)
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class PreviewUrlTestCase(unittest.TestCase):
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def test_simple(self):
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html = """
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<html>
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<head><title>Foo</title></head>
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<body>
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Some text.
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</body>
|
||||
</html>
|
||||
"""
|
||||
|
||||
og = decode_and_calc_og(html, "http://example.com/test.html")
|
||||
|
||||
self.assertEquals(og, {
|
||||
"og:title": "Foo",
|
||||
"og:description": "Some text."
|
||||
})
|
||||
|
||||
def test_comment(self):
|
||||
html = """
|
||||
<html>
|
||||
<head><title>Foo</title></head>
|
||||
<body>
|
||||
<!-- HTML comment -->
|
||||
Some text.
|
||||
</body>
|
||||
</html>
|
||||
"""
|
||||
|
||||
og = decode_and_calc_og(html, "http://example.com/test.html")
|
||||
|
||||
self.assertEquals(og, {
|
||||
"og:title": "Foo",
|
||||
"og:description": "Some text."
|
||||
})
|
||||
|
||||
def test_comment2(self):
|
||||
html = """
|
||||
<html>
|
||||
<head><title>Foo</title></head>
|
||||
<body>
|
||||
Some text.
|
||||
<!-- HTML comment -->
|
||||
Some more text.
|
||||
<p>Text</p>
|
||||
More text
|
||||
</body>
|
||||
</html>
|
||||
"""
|
||||
|
||||
og = decode_and_calc_og(html, "http://example.com/test.html")
|
||||
|
||||
self.assertEquals(og, {
|
||||
"og:title": "Foo",
|
||||
"og:description": "Some text.\n\nSome more text.\n\nText\n\nMore text"
|
||||
})
|
||||
|
||||
def test_script(self):
|
||||
html = """
|
||||
<html>
|
||||
<head><title>Foo</title></head>
|
||||
<body>
|
||||
<script> (function() {})() </script>
|
||||
Some text.
|
||||
</body>
|
||||
</html>
|
||||
"""
|
||||
|
||||
og = decode_and_calc_og(html, "http://example.com/test.html")
|
||||
|
||||
self.assertEquals(og, {
|
||||
"og:title": "Foo",
|
||||
"og:description": "Some text."
|
||||
})
|
||||
|
|
|
|||
Loading…
Reference in New Issue