I need to traverse the XML tree to add sub element when the value is less than 5. For example, this XML can be modified into
<?xml version="1.0" encoding="UTF-8"?>
<A value="45">
<B value="30">
<C value="10"/>
<C value ="20"/>
</B>
<B value="15">
<C value = "5" />
<C value = "10" />
</B>
</A>
this XML.
<?xml version="1.0" encoding="UTF-8"?>
<A value="45">
<B value="30">
<C value="10"/>
<C value ="20"/>
</B>
<B value="15">
<C value = "5"><D name="error"/></C>
<C value = "10" />
</B>
</A>
How can I do that with Python's ElementTree?
Creating XML Document using Python First, we import minidom for using xml. dom . Then we create the root element and append it to the XML. After that creating a child product of parent namely Geeks for Geeks.
The xml.etree.ElementTree module implements a simple and efficient API for parsing and creating XML data. Changed in version 3.3: This module will use a fast implementation whenever available.
You probably made a typo because in the example, an error element is appended as the child of an element whose value is 10, which is not less than 5. But I think this is the idea:
#!/usr/bin/env python
from xml.etree.ElementTree import fromstring, ElementTree, Element
def validate_node(elem):
for child in elem.getchildren():
validate_node(child)
value = child.attrib.get('value', '')
if not value.isdigit() or int(value) < 5:
child.append(Element('D', {'name': 'error'}))
if __name__ == '__main__':
import sys
xml = sys.stdin.read() # read XML from standard input
root = fromstring(xml) # parse into XML element tree
validate_node(root)
ElementTree(root).write(sys.stdout, encoding='utf-8')
# write resulting XML to standard output
Given this input:
<?xml version="1.0" encoding="UTF-8"?>
<A value="45">
<B value="30">
<C value="1"/>
<C value="20"/>
</B>
<B value="15">
<C value="5" />
<C value="10" />
<C value="foo" />
</B>
</A>
This is is the output:
<A value="45">
<B value="30">
<C value="1"><D name="error" /></C>
<C value="20" />
</B>
<B value="15">
<C value="5" />
<C value="10" />
<C value="foo"><D name="error" /></C>
</B>
</A>
ElementTree's iter (or getiterator for Python <2.7) willl recursively return all the nodes in a tree, then just test for your condition and create the SubElement:
from xml.etree import ElementTree as ET
tree = ET.parse(input)
for e in tree.getiterator():
if int(e.get('value')) < 5:
ET.SubElement(e,'D',dict(name='error'))
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