Check if XML Element has children or not, in ElementTree

Question

I retrieve an XML documents this way:

import xml.etree.ElementTree as ET

root = ET.parse(urllib2.urlopen(url))
for child in root.findall("item"):
  a1 = child[0].text # ok
  a2 = child[1].text # ok
  a3 = child[2].text # ok
  a4 = child[3].text # BOOM
  # ...

The XML looks like this:

<item>
  <a1>value1</a1>
  <a2>value2</a2>
  <a3>value3</a3>
  <a4>
    <a11>value222</a11>
    <a22>value22</a22>
  </a4>
</item>

How do I check if a4 (in this particular case, but it might've been any other element) has children?

Answer 1

You could try the list function on the element:

>>> xml = """<item>
  <a1>value1</a1>
  <a2>value2</a2>
  <a3>value3</a3>
  <a4>
    <a11>value222</a11>
    <a22>value22</a22>
  </a4>
</item>"""
>>> root = ET.fromstring(xml)
>>> list(root[0])
[]
>>> list(root[3])
[<Element 'a11' at 0x2321e10>, <Element 'a22' at 0x2321e48>]
>>> len(list(root[3]))
2
>>> print "has children" if len(list(root[3])) else "no child"
has children
>>> print "has children" if len(list(root[2])) else "no child"
no child
>>> # Or simpler, without a call to list within len, it also works:
>>> print "has children" if len(root[3]) else "no child"
has children

I modified your sample because the findall function call on the item root did not work (as findall will search for direct descendants, and not the current element). If you want to access text of the subchildren afterward in your working program, you could do:

for child in root.findall("item"):
  # if there are children, get their text content as well.
  if len(child): 
    for subchild in child:
      subchild.text
  # else just get the current child text.
  else:
    child.text

This would be a good fit for a recursive though.

Answer 2

The simplest way I have been able to find is to use the bool value of the element directly. This means you can use a4 in a conditional statement as-is:

a4 = Element('a4')
if a4:
    print('Has kids')
else:
    print('No kids yet')

a4.append(Element('x'))
if a4:
    print('Has kids now')
else:
    print('Still no kids')

Running this code will print

No kids yet
Has kids now

The boolean value of an element does not say anything about text, tail or attributes. It only indicates the presence or absence of children, which is what the original question was asking.

Answer 3

I would personally recommend that you use an xml parser that fully supports xpath expressions. The subset supported by xml.etree is insufficient for tasks like this.

For example, in lxml I can do:

"give me all children of the children of the <item> node":

doc.xpath('//item/*/child::*') #equivalent to '//item/*/*', if you're being terse
Out[18]: [<Element a11 at 0x7f60ec1c1348>, <Element a22 at 0x7f60ec1c1888>]

or,

"give me all of <item>'s children that have no children themselves":

doc.xpath('/item/*[count(child::*) = 0]')
Out[20]: 
[<Element a1 at 0x7f60ec1c1588>,
 <Element a2 at 0x7f60ec1c15c8>,
 <Element a3 at 0x7f60ec1c1608>]

or,

"give me ALL of the elements that don't have any children":

doc.xpath('//*[count(child::*) = 0]')
Out[29]: 
[<Element a1 at 0x7f60ec1c1588>,
 <Element a2 at 0x7f60ec1c15c8>,
 <Element a3 at 0x7f60ec1c1608>,
 <Element a11 at 0x7f60ec1c1348>,
 <Element a22 at 0x7f60ec1c1888>]

# and if I only care about the text from those nodes...
doc.xpath('//*[count(child::*) = 0]/text()')
Out[30]: ['value1', 'value2', 'value3', 'value222', 'value22']

Answer 4

As of today, using Python 3.9 you can use the len() function on an ElementTree element.

In this case, for example:

if len(child[3]) > 0:
    a4 = child[3].text

Answer 5

Update 2022:

The elements are iterable, and also the length operation is implemented. So you can directly use it to check whether an element as children like this:

import xml.etree.ElementTree as ET
xml = """<item>
  <a1>value1</a1>
  <a2>value2</a2>
  <a3>value3</a3>
  <a4>
    <a11>value222</a11>
    <a22>value22</a22>
  </a4>
</item>"""
root = ET.fromstring(xml)

def traverse(e_):
    for c in e_:
        if not c:  # element c has no children
            print(f"text of element: '{c.text}'")
        else:
            traverse(c)

traverse(root)

Produces the following output:

traverse(root)

text of element: 'value1'
text of element: 'value2'
text of element: 'value3'
text of element: 'value222'
text of element: 'value22'

Deprecated solution (Python 2.7, <Python 3.9):

The element class has the get children method. So you should use something like this, to check if there are children and store result in a dictionary by key=tag name:

result = {}
for child in root.findall("item"):
   if child.getchildren() == []:
      result[child.tag] = child.text

Answer 6

You can use the iter method

import xml.etree.ElementTree as ET

etree = ET.parse('file.xml')
root = etree.getroot()
a = []
for child in root.iter():
    if child.text:
        if len(child.text.split()) > 0:
            a.append(child.text)
print(a)

Answer 7

It is possible to use a very simple method

list(<element>)

if list is empty then there is no child there.