mirror of
https://github.com/dnlbauer/django-signposting.git
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0cd321112f
* use rdflib to extract signposts from jsonld * use rdflib to extract signposts from jsonld * linting * unit tests for jsonld middleware * update readme * update flake pipeline --------- Co-authored-by: Daniel Bauer <daniel.bauer@senckenberg.de>
130 lines
4.4 KiB
Python
130 lines
4.4 KiB
Python
from typing import Callable
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from django.http import HttpRequest, HttpResponse
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from signposting import Signpost, LinkRel
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from bs4 import BeautifulSoup
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import re
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import json
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from django.utils.deprecation import MiddlewareMixin
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from django.conf import settings
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from rdflib import Graph
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from . import sparql
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class SignpostingMiddleware:
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def __init__(self, get_response: Callable[[HttpRequest], HttpResponse]):
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self.get_response = get_response
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def __call__(self, request: HttpRequest) -> HttpResponse:
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response = self.get_response(request)
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# no signposts on errors
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if response.status_code >= 400:
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return response
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if not hasattr(response, "_signposts"):
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return response
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self._add_signposts(response, response._signposts)
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return response
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def _add_signposts(self, response: HttpResponse, signposts: list[Signpost]):
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"""Adds signposting headers to the respones.
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params:
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response - the response object
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signposts - a list of Signposts
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"""
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link_snippets = []
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for signpost in signposts:
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link_snippets.append(f'<{signpost.target}> ; rel="{signpost.rel}"')
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if signpost.type:
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link_snippets[-1] += f' ; type="{signpost.type}"'
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response["Link"] = " , ".join(link_snippets)
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class JsonLdSignpostingParserMiddleware(MiddlewareMixin):
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def is_url(self, url: str) -> bool:
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url_pattern = re.compile(
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r"^(https?|ftp)://" # protocol
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r"(?:(?:[a-zA-Z0-9-_]+\.)?[a-zA-Z0-9-]+\.[a-zA-Z]{2,6})" # domain
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r"(?::\d{1,5})?" # optional port
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r"(?:/.*)?$" # path
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)
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return bool(url_pattern.match(url))
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def select_url(self, elements: tuple[str, ...]) -> str | None:
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for elem in elements[::-1]:
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if self.is_url(str(elem)):
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return str(elem)
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return None
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def _jsonld_to_signposts(self, jsonld: dict) -> dict:
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signposts = []
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# TODO use jsonld context in query as prefix
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g = Graph().parse(data=json.dumps(jsonld), format="json-ld")
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rootElement = next(iter(sparql.root_element_query(g)), None)
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if rootElement:
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rootElement = rootElement[0]
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else:
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print("No root element found")
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return {}
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types = sparql.type_query(g, rootElement)
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for type in types:
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signposts.append(Signpost(LinkRel.type, str(type[0])))
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authors = sparql.author_query(g, rootElement)
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for author in authors:
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author = self.select_url(author)
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if author:
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signposts.append(Signpost(LinkRel.author, author))
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license = next(iter(sparql.license_query(g, rootElement)), [])
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license = self.select_url(license)
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if license:
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signposts.append(Signpost(LinkRel.license, license))
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citations = sparql.cite_query(g, rootElement)
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for citation in citations:
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citation = self.select_url(citation)
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if citation:
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signposts.append(Signpost(LinkRel.cite_as, citation))
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sameas = sparql.sameas_query(g, rootElement)
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for sa in sameas:
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sa_media_type = sa[-1]
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sa = self.select_url(sa[:-1])
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if sa:
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signposts.append(Signpost(LinkRel.describedby, sa, sa_media_type))
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items = sparql.item_query(g, rootElement)
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for item in items:
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item_media_type = item[-1]
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item = self.select_url(item[:-1])
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if item:
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signposts.append(Signpost(LinkRel.item, item, item_media_type))
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return signposts
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def process_response(
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self, request: HttpRequest, response: HttpResponse
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) -> HttpResponse:
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if not getattr(settings, "SIGNPOSTING_PARSE_JSONLD", True):
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return response
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if response.get("Content-Type", "").startswith("text/html"):
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soup = BeautifulSoup(response.content, "html.parser")
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for script in soup.find_all("script", type="application/ld+json"):
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try:
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jsonld = json.loads(script.string)
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signposts = self._jsonld_to_signposts(jsonld)
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response._signposts = signposts
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except json.JSONDecodeError as e:
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print(e)
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continue
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return response
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