lxml

Bug #2055758
Comment #0

Comment 0 for bug 2055758

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kwunlyou (zju-liukun) wrote on 2024-03-02:

I have a XML and need to remove a few types of tags. I used the iter method to check each element. I noticed if there is a nested element its child is also deleted. The following tag will not be deleted. For example as follows, the tag delete2 is a child of delete1 and both will be removed. The tag section can be deleted for some reason. Is this a bug? Or did I miss something? Thanks.

# %%
from lxml import etree

# unexpected output when nested elements are deleted
xml_str = """
<spdoc>
  <commentary>
    <body>
      <delete1>
        <delete2>
        </delete2>
      </delete1>
      <section name="delete">
      </section>
    </body>
  </commentary>
</spdoc>
"""
# works
# xml_str = """
# <spdoc>
# <commentary>
# <body>
# <delete1>
# </delete1>

Versions:
Python : sys.version_info(major=3, minor=10, micro=13, releaselevel='final', serial=0)
lxml.etree : (5, 1, 0, 0)
libxml used : (2, 12, 3)
libxml compiled : (2, 12, 3)
libxslt used : (1, 1, 39)
libxslt compiled : (1, 1, 39)
# <delete2>
# </delete2>
# <section name="delete">
# </section>
# </body>
# </commentary>
# </spdoc>
# """

root = etree.fromstring(xml_str)
for element in root.iter():
    is_remove = False
    if element.tag == "delete1":
        is_remove = True
    if element.tag == "delete2":
        is_remove = True
    if element.tag == "section" and element.attrib.get("name") == "delete":
        is_remove = True
    print(f"{element} {is_remove}")
    if is_remove:
        element.getparent().remove(element)

print(etree.tostring(root, encoding="utf-8").decode("utf-8"))

# the unexpected output is :

# <Element spdoc at 0x103489680> False
# <Element commentary at 0x103489640> False
# <Element body at 0x1034b5540> False
# <Element delete1 at 0x1037eb700> True
# <Element delete2 at 0x1037eba40> True
# <spdoc>
# <commentary>
# <body>
# <section name="delete">
# </section>
# </body>
# </commentary>
# </spdoc>

# %%
from lxml import etree

# unexpected output when nested elements are deleted
xml_str = """  
<spdoc>
  <commentary>
    <body>
      <delete1>
        <delete2>
        </delete2>
      </delete1>
      <section name="delete">
      </section>
    </body>
  </commentary>
</spdoc>
"""
# works
# xml_str = """  
# <spdoc>
#   <commentary>
#     <body>
#       <delete1>
#       </delete1>

Versions:
Python              : sys.version_info(major=3, minor=10, micro=13, releaselevel='final', serial=0)
lxml.etree          : (5, 1, 0, 0)
libxml used         : (2, 12, 3)
libxml compiled     : (2, 12, 3)
libxslt used        : (1, 1, 39)
libxslt compiled    : (1, 1, 39)
#       <delete2>
#       </delete2>      
#       <section name="delete">
#       </section>
#     </body>
#   </commentary>
# </spdoc>
# """

print(etree.tostring(root, encoding="utf-8").decode("utf-8"))

# the unexpected output is :

# <Element spdoc at 0x103489680> False
# <Element commentary at 0x103489640> False
# <Element body at 0x1034b5540> False
# <Element delete1 at 0x1037eb700> True
# <Element delete2 at 0x1037eba40> True
# <spdoc>
#   <commentary>
#     <body>
#       <section name="delete">
#       </section>
#     </body>
#   </commentary>
# </spdoc>