beautifulsoup: find_all on bs4.element.ResultSet object or list?

Question

Hi so I apply find_all on a beautifulsoup object, and find something, which is an bs4.element.ResultSet object or a list.

I want to further do find_all in there, but it's not allowed on a bs4.element.ResultSet object. I can loop through each element of the bs4.element.ResultSet object to do find_all. But can I avoid looping and just convert it back to a beautifulsoup object?

See code for details please. Thanks

html_1 = """
<table>
    <thead>
        <tr class="myClass">
            <th>A</th>
            <th>B</th>
            <th>C</th>
            <th>D</th>
        </tr>
    </thead>
</table>
"""
soup = BeautifulSoup(html_1, 'html.parser')

type(soup) #bs4.BeautifulSoup

# do find_all on beautifulsoup object
th_all = soup.find_all('th')

# the result is of type bs4.element.ResultSet or similarly list
type(th_all) #bs4.element.ResultSet
type(th_all[0:1]) #list

# now I want to further do find_all
th_all.find_all(text='A') #not work

# can I avoid this need of loop?
for th in th_all:
    th.find_all(text='A') #works

Solution

ResultSet class is a subclass of a list and not a Tag class which has the find* methods defined. Looping through the results of find_all() is the most common approach:

th_all = soup.find_all('th')
result = []
for th in th_all:
    result.extend(th.find_all(text='A'))

Usually, CSS selectors may help you solve it in one go except that not everything you can do with find_all() is possible with the select() method. For instance, there is no "text" search available in bs4 CSS selectors. But, if, for example, you had to find all, say, b elements inside th elements, you could do:

soup.select("th td")