Django - UnboundLocalError：分配前引用的局部变量“image_link”

Question

我编写了一个解析新闻文章提要的函数。

def save_new_articles(feed, source_id, category_id):
    channel_feed_title = feed.channel.title.title()
    channel_feed_link = feed.channel.link
    channel_feed_desc = feed.channel.description
    official_source_id = source_id
    post_category_id = category_id

    for item in feed.entries:
        parsed_summary = item.summary
        soup = BeautifulSoup(parsed_summary, 'lxml')
        images = soup.findAll('img')
        for image in images:
            image_url_link = (image['src'])
            if image_url_link is not None:
                image_link = image_url_link
            else:
                image_link = "https://www.publicdomainpictures.net/pictures/280000/velka/not-found-image-15383864787lu.jpg"

        parsed_title = item.title
        formatted = re.sub("<.*?>", "", parsed_title)
        post_title = formatted

        post_link = item.link

        description = item.description
        output_summary = re.sub("<.*?>", "", description)

        title = item.title
        capital = title.title()
        tags = capital.split()

        date_published = parser.parse(item.published)

        if not Posts.objects.filter(guid=item.guid).exists():
            post = Posts(
                title = post_title,
                link = post_link,
                summary = output_summary,
                image_url = image_link,
                tags = tags,
                pub_date = date_published,
                guid = item.guid,
                feed_title = channel_feed_title,
                feed_link = channel_feed_link,
                feed_description = channel_feed_desc,
                source_id = official_source_id,
                category_id = post_category_id
            )
            post.save()
            
        else:
            logger.info("Duplicate Post Detected! Skipping...")

但是在运行代码时我得到：

image_url = image_link,
UnboundLocalError: local variable 'image_link' referenced before assignment

我不明白错误来自哪里，因为我在上面的image for loop statement 中定义了image_link。我已经检查了类似的答案，但我似乎没有找到合适的答案。请帮我调试一下。

Answer 1

当images（使用soup.findAll('img') 初始化）为空时会发生此错误。

可能您不仅有没有img 标签的item.summary，而且由于之前的一些错误，它也可能只是空的。

因此，要修复您的代码，您应该在此之前初始化 image_link：

if not Posts.objects.filter(guid=item.guid).exists():

按照我的假设，使用您的默认值：

image_link = "https://www.publicdomainpictures.net/pictures/280000/velka/not-found-image-15383864787lu.jpg"

例如，像这样，而不是：

        for image in images:
            image_url_link = (image['src'])
            if image_url_link is not None:
                image_link = image_url_link
            else:
                image_link = "https://www.publicdomainpictures.net/pictures/280000/velka/not-found-image-15383864787lu.jpg"

你可以这样：

        image_link = "https://www.publicdomainpictures.net/pictures/280000/velka/not-found-image-15383864787lu.jpg"
        for image in images:
            image_url_link = (image['src'])
            if image_url_link is not None:
                image_link = image_url_link