如何使用Beautiful Soup 4来查找属性

Question

I'm trying to parse html like the following:

<tbody>
    <tr class data-row="0">
        <td align="right"></td>
    </tr>
    <tr class data-row="1">
        <td align="right"></td>
    </tr>
    <tr class="thead over_theader" data-row="2">
        <td align="right"></td>
    </tr>
    <tr class="thead" data-row="3">
        <td align="right"></td>
    </tr>
    <tr class data-row="4">
        <td align="right"></td>
    </tr>
    <tr class data-row="5">
        <td align="right"></td>
    </tr>
</tbody>

I want to obtain all tr tags (and their children) where class is not specified. For the example above, that means I want the tr tags where data-row is not 2 or 3.

How do I do this using Beautiful Soup 4?

I tried

tableBody = soup.findAll('tbody')
rows = tableBody[0].findAll(attrs={"class":""})

but this returned a type bs4.element.ResultSet of length 8 (ie it included the tr children with td tags) when I wanted a bs4.element.ResultSet of length 4 (one for each tr tag with class = "" ).

Answer 1

Your method actually works for me when I specify the tr tag name:

>>> from bs4 import BeautifulSoup
>>> data = """
... <tbody>
...     <tr class data-row="0">
...         <td align="right"></td>
...     </tr>
...     <tr class data-row="1">
...         <td align="right"></td>
...     </tr>
...     <tr class="thead over_theader" data-row="2">
...         <td align="right"></td>
...     </tr>
...     <tr class="thead" data-row="3">
...         <td align="right"></td>
...     </tr>
...     <tr class data-row="4">
...         <td align="right"></td>
...     </tr>
...     <tr class data-row="5">
...         <td align="right"></td>
...     </tr>
... </tbody>
... """
>>> soup = BeautifulSoup(data, "html.parser")
>>> len(soup.find_all("tr", class_=""))
4

Alternatively, you can use a tr[class=""] CSS selector :

>>> len(soup.select('tr[class=""]'))
4

Answer 2

find_all will, by default, search recursively. So the td tags are valid matches.

Docs :

If you call mytag.find_all() , Beautiful Soup will examine all the descendants of mytag : its children, its children's children, and so on. If you only want Beautiful Soup to consider direct children, you can pass in recursive=False

So you might write, for example:

tableBody = soup.findAll('tbody')
rows = tableBody[0].find_all(attrs={"class":""}, recursive=False)

print(len(rows))
for r in rows:
    print('---')
    print(r)

Output:

4
---
<tr class="" data-row="0">
<td align="right"></td>
</tr>
---
<tr class="" data-row="1">
<td align="right"></td>
</tr>
---
<tr class="" data-row="4">
<td align="right"></td>
</tr>
---
<tr class="" data-row="5">
<td align="right"></td>
</tr>