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xml.etree.ElementTree findall() fails when using custom TreeBuilder #79122

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jackjansen opened this issue Oct 9, 2018 · 5 comments
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xml.etree.ElementTree findall() fails when using custom TreeBuilder #79122

jackjansen opened this issue Oct 9, 2018 · 5 comments
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@serhiy-storchaka
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3.7 (EOL) end of life 3.8 only security fixes stdlib Python modules in the Lib dir topic-XML type-bug An unexpected behavior, bug, or error

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@jackjansen
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BPO 34941
Nosy @jackjansen, @scoder, @serhiy-storchaka, @miss-islington
PRs
  • bpo-34941: Fix searching Element subclasses. #9766
  • [3.7] bpo-34941: Fix searching Element subclasses. (GH-9766) #9867
  • [3.6] bpo-34941: Fix searching Element subclasses. (GH-9766) #9868
    		•
    Files
  • testetns.py
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2018-10-14.08:41:19.590>
created_at = <Date 2018-10-09.09:32:14.985>
labels = ['expert-XML', '3.8', 'type-bug', 'library', '3.7']
title = 'xml.etree.ElementTree findall() fails when using custom TreeBuilder'
updated_at = <Date 2018-10-14.08:41:19.589>
user = 'https://github.com/jackjansen'

    bugs.python.org fields:

    activity = <Date 2018-10-14.08:41:19.589>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2018-10-14.08:41:19.590>
closer = 'serhiy.storchaka'
components = ['Library (Lib)', 'XML']
creation = <Date 2018-10-09.09:32:14.985>
creator = 'jackjansen'
dependencies = []
files = ['47859']
hgrepos = []
issue_num = 34941
keywords = ['patch']
message_count = 5.0
messages = ['327385', '327388', '327695', '327696', '327698']
nosy_count = 5.0
nosy_names = ['jackjansen', 'scoder', 'eli.bendersky', 'serhiy.storchaka', 'miss-islington']
pr_nums = ['9766', '9867', '9868']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue34941'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8']
    @jackjansen
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    When using a TreeBuilder with a custom factory (returning a subclass of Element with some extra functionality) there is an issue with findall().

    XPaths using an indexed predicate no longer work: the findall() result is always empty. The attached test script shows the problem.

    I have analysed this as far as finding that the issue is in ElementPath.prepare_predicate.<locals>.select(), the last one. Specifically, the statement
    elems = list(parent.findall(elem.tag))
    always returns an empty list (if the Element class is subclassed).

    When using Python 2.7 everything works fine. When adding a findall() method to the Element subclass that simply calls Element.findall() everything also works fine. I suspect some issue with the _elementtree C implementation but I don't understand it.

    @jackjansen jackjansen added 3.7 (EOL) end of life stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Oct 9, 2018
    @jackjansen
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    Correction to the last line:
    When using Python 2.7 everything works fine. When adding a findall() method to the Element subclass that simply calls ElementPath.findall() everything also works fine. I suspect some issue with the _elementtree C implementation but I don't understand it.

    @serhiy-storchaka serhiy-storchaka added topic-XML 3.8 only security fixes labels Oct 9, 2018
    @serhiy-storchaka serhiy-storchaka self-assigned this Oct 9, 2018
    @serhiy-storchaka
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    New changeset b11c566 by Serhiy Storchaka in branch 'master':
    bpo-34941: Fix searching Element subclasses. (GH-9766)
    b11c566

    @miss-islington
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    New changeset b1c8003 by Miss Islington (bot) in branch '3.7':
    bpo-34941: Fix searching Element subclasses. (GH-9766)
    b1c8003

    @serhiy-storchaka
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    New changeset 7c1c42b by Serhiy Storchaka in branch '3.6':
    [3.6] bpo-34941: Fix searching Element subclasses. (GH-9766) (GH-9868)
    7c1c42b

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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    @serhiy-storchaka serhiy-storchaka

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