python - Complex Beautiful Soup query

Question

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 /> 

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%">.

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

Answer 1

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).

If you want a one-liner:

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

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.