gh-61290: Fix serializing attributes with the default_namespace option - #156747
Merged
serhiy-storchaka merged 3 commits intoSep 13, 2026
Merged
Conversation
… option The default namespace declaration does not apply to attribute names, so an unqualified attribute name can be written as is, and a qualified attribute name always needs a prefix, even if it is in the default namespace. They are now encoded separately from element names, and the namespaces table maps prefixes to URIs, because a URI can need both the default declaration and a prefixed one.
register_namespace("", uri) still makes it the default namespace, unless the
default_namespace option is used for other uri. Serializing such tree no
longer produces two xmlns attributes (pythongh-118416).
…ult-namespace-attrs # Conflicts: # Lib/test/test_xml_etree.py
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Serialization with the default_namespace option failed for any attribute without a namespace:
But a default namespace declaration does not apply to attribute names (Namespaces in XML, 6.2), so an unqualified attribute name can be written as is. For the same reason a qualified attribute name always needs a prefix, even if it is in the default namespace, and its namespace has to be declared twice:
lxml serializes it the same way. Attribute names are now encoded separately from element names, and the namespaces table maps prefixes to URIs, because one URI can need both the default declaration and a prefixed one.
This also fixes gh-113581, the same bug seen from the other side: a qualified attribute name in the default namespace was written without a prefix, so its namespace was silently lost when the document was parsed back.