previews.py 文件源码

def fetch_og_preview(content, urls):
    """Fetch first opengraph entry for a list of urls."""
    for url in urls:
        # See first if recently cached already
        if OpenGraphCache.objects.filter(url=url, modified__gte=now() - datetime.timedelta(days=7)).exists():
            opengraph = OpenGraphCache.objects.get(url=url)
            Content.objects.filter(id=content.id).update(opengraph=opengraph)
            return opengraph
        try:
            og = OpenGraph(url=url, parser="lxml")
        except AttributeError:
            continue
        if not og or ("title" not in og and "site_name" not in og and "description" not in og and "image" not in og):
            continue
        try:
            title = og.title if "title" in og else og.site_name if "site_name" in og else ""
            description = og.description if "description" in og else ""
            image = og.image if "image" in og and not content.is_nsfw else ""
            try:
                with transaction.atomic():
                    opengraph = OpenGraphCache.objects.create(
                        url=url,
                        title=truncate_letters(safe_text(title), 250),
                        description=safe_text(description),
                        image=safe_text(image),
                    )
            except DataError:
                continue
        except IntegrityError:
            # Some other process got ahead of us
            opengraph = OpenGraphCache.objects.get(url=url)
            Content.objects.filter(id=content.id).update(opengraph=opengraph)
            return opengraph
        Content.objects.filter(id=content.id).update(opengraph=opengraph)
        return opengraph
    return False