复杂的 Beautiful Soup 查询 [英] Complex Beautiful Soup query

问题描述

这是我正在使用 Beautiful Soup 探索的 HTML 文件的片段.

Here is a snippet of an HTML file I'm exploring with Beautiful Soup.

<td width="50%">
    <strong class="sans"><a href="http:/website">Site</a></strong> <br /> 

我想为任何具有 并且位于 的行获取 代码>.

I would like to get the <a href> for any line which has the <strong class="sans"> and which is inside a <td width="50%">.

是否可以使用 Beautiful Soup 查询 HTML 文件中的多个条件?

Is it possible to query a HTML file for those multiple conditions using Beautiful Soup ?

推荐答案

BeautifulSoup 的搜索机制接受可调用的，文档似乎为您的案例推荐:如果您需要对标签的属性施加复杂或互锁的限制，请通过在名称的可调用对象中，...".(好吧……他们专门讨论属性，但建议反映了 BeautifulSoup API 的潜在精神.

BeautifulSoup's search mechanisms accept a callable, which the docs appear to recommend for your case: "If you need to impose complex or interlocking restrictions on a tag's attributes, pass in a callable object for name,...". (ok... they're talking about attributes specifically, but the advice reflects an underlying spirit to the BeautifulSoup API).

如果你想要一个单线:

soup.findAll(lambda tag: tag.name == 'a' and 
tag.findParent('strong', 'sans') and 
tag.findParent('strong', 'sans').findParent('td', attrs={'width':'50%'}))

我在这个例子中使用了一个 lambda，但在实践中，如果你有多个链式需求，你可能想要定义一个可调用函数，因为这个 lambda 必须创建两个 findParent('strong', 'sans') 调用以避免在 标签没有 strong 父标签时引发异常.使用适当的函数，可以使测试更有效率.

I've used a lambda in this example, but in practice you may want to define a callable function if you have multiple chained requirements as this lambda has to make two findParent('strong', 'sans') calls to avoid raising an exception if an <a> tag has no strong parent. Using a proper function, you could make the test more efficient.

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