Beautiful Soup

support string attribute on NavigableString objects

Bug #2044794 reported by Chris Papademetrious
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Beautiful Soup
Fix Committed
Wishlist
Unassigned

Bug Description

This is a wishlist item.

Currently, Tag and NavigableString objects use different mechanisms to change their text content:

* Tag objects use the "string" attribute
* NavigableString objects use the "replace_with()" method

For example,

====
>>> from bs4 import BeautifulSoup
>>> soup = BeautifulSoup('AAA<b>BBB</b>', 'lxml')
>>> soup.find(string=True).replace_with('CCC')
'AAA'
>>> soup.find('b').string = 'DDD'
>>> soup
<html><body><p>CCC<b>DDD</b></p></body></html>
====

It would be nice if NavigableString objects *also* supported the "string" attribute, which would be convenient for code that must handle both object types. (This is how I ran into this; I used conditionals for now.)

This gives no indication of error, but it has no effect:

===
>>> soup.find(string=True).string = 'EEE'
>>> soup
<html><body><p>CCC<b>DDD</b></p></body></html>
===

I think this enhancement request is consistent with the fact that the four basic object types already share many attributes and methods.

Revision history for this message
Leonard Richardson (leonardr) wrote :

It turns out this is already done; I implemented this in the 4.13 branch a while ago, while reconciling the type system, but I didn't mention it in the CHANGELOG.

Changed in beautifulsoup:
status: New → Fix Committed
importance: Undecided → Wishlist
Revision history for this message
Chris Papademetrious (chrispitude) wrote (last edit ):

Thanks for this enhancement! If I run the following code in the 4.13 branch:

====
from bs4 import BeautifulSoup
soup = BeautifulSoup('AAA<b>BBB</b>', 'lxml')
tag = soup.find('b')
navstr = soup.find(string=True)
====

I can indeed see that both types now allow .string to be read:

====
>>> tag.string
'BBB'
>>> navstr.string
'AAA'
====

However, only Tag allows .string to be modified:

====
>>> tag.string = 'CCC'
>>> navstr.string = 'DDD'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: can't set attribute 'string'
====

(This is the actual use case I ran into in my code.)

Is it possible to implement this?

Revision history for this message
Leonard Richardson (leonardr) wrote :

I could be wrong, but I don't think that's possible. NavigableString doesn't contain a string, it actually is a subclass of str, and Python strings are immutable. It would be like trying to get this to work:

"foo".string = "bar"

Revision history for this message
Chris Papademetrious (chrispitude) wrote :

That makes sense. Thank you!

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