add xml node to xml file with python

Question

I wonder if it is better add an element by opening file, search 'good place' and add string which contains xml code. Or use some library... i have no idea. I know how can i get nodes and properties from xml through for example lxml but what's the simpliest and the best way to add?

Answer 1

You could use lxml.etree.Element to make the xml node(s), and use append or insert to attach them into xml document:

data='''\
<root>
<node1>
  <node2 a1="x1"> ... </node2>
  <node2 a1="x2"> ... </node2>
  <node2 a1="x1"> ... </node2>
</node1>
</root>
'''
doc = lxml.etree.XML(data)
e=doc.find('node1')
child = lxml.etree.Element("node3",attrib={'a1':'x3'})
child.text='...'
e.insert(1,child)
print(lxml.etree.tostring(doc))

yields:

<root>
    <node1>
      <node2 a1="x1"> ... </node2>
      <node3 a1="x3">...</node3><node2 a1="x2"> ... </node2>
      <node2 a1="x1"> ... </node2>
    </node1>
    </root>

Answer 2

The safest way to add nodes to an XML document is to load it into a DOM, add the nodes programmatically and write it out again. There are several Python XML libraries. I have used minidom, but I have no reason to recommend it specifically over the others.