Python - How can I find out if a specific XML node is present using Python?

Question

Here is a sample of some XML code I have:

<VAST version="2.0">
<Ad id="602678">
<InLine>
<AdSystem>Acudeo Compatible</AdSystem>
<AdTitle>NonLinear Test Campaign 1</AdTitle>
<Description>NonLinear Test Campaign 1</Description>
<Creatives>
<Creative AdID="602678-NonLinear">
</Creative>
</Creatives>
</InLine>
</Ad>
</VAST>

This XML is served online so I hit a specific URL in order to get this data back. However, in some cases, nothing is returned so I am looking for a way to verify whether or not the "Creatives" node is present in whatever is returned at any given time. I have tried BeautifulSoup with no luck but I think that is more for HTML rather than XML. Any help is greatly appreciated, thanks.

What's wrong with plain-text checking? i.e. if "<Creatives>" in your_returned_payload: ... — zwer
– zwer, Commented Jun 7, 2017 at 2:18
I think the trouble I am having is with parsing the XML data itself after trying to pull it from the web URL I am hitting. I will update by POST with my code. — user7681184
– user7681184, Commented Jun 7, 2017 at 2:23

score 1 · Accepted Answer · 2017-06-07 09:31:54Z

1

Let's suppose you retrieve the XML from an URL like this:

import requests

r = requests.get(url)
if r.status_code == 200:
    xml_tag_exists(r)

Then you just have to build a simple function which will return True/False based on whether the required XML tag exists:

def xml_tag_exists(r):
    return '<Creatives>' in r.text

For example, let's take the following URL:

>>> import requests
>>> url = 'http://www.w3schools.com/xml/plant_catalog.xml'
>>> r = requests.get(url)
>>> if r.status_code == 200:
...     print(r.text)

The above will return an XML of the following form:

<CATALOG>
  <PLANT>
    <COMMON>Bloodroot</COMMON>
    <BOTANICAL>Sanguinaria canadensis</BOTANICAL>
    <ZONE>4</ZONE>
    <LIGHT>Mostly Shady</LIGHT>
    <PRICE>$2.44</PRICE>
    <AVAILABILITY>031599</AVAILABILITY>
  </PLANT>
  <PLANT>
    <COMMON>Columbine</COMMON>
    <BOTANICAL>Aquilegia canadensis</BOTANICAL>
    <ZONE>3</ZONE>
    <LIGHT>Mostly Shady</LIGHT>
    <PRICE>$9.37</PRICE>
    <AVAILABILITY>030699</AVAILABILITY>
  </PLANT>
  ...
</CATALOG>

Which if we check for some tag:

>>> if '<CATALOG>' in r.text:
...     print(True)
...
True

So, if I were to do this, I'd write something like this:

import requests


def xml_tag_exists(r):
    return '<Creatives>' in r.text


def main():
    r = requests.get('your_url_goes_here')
    if r.status_code == 200:
        xml_tag_exists(r)

if __name__ == '__main__':
    main()

edited Jun 7, 2017 at 9:31

answered Jun 7, 2017 at 5:13

user6165050

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2 Comments

zwer Over a year ago

That will work only if the returned content is only "<Creatives>" and nothing else.

user6165050 Over a year ago

@zwer it was just a typo. It was meant to be "<Creatives>" in r.text. Thanks for head-ups. Fixed now

Tomasz Adamczyk · Accepted Answer · 2017-06-07 05:20:39Z

0

You can also use XPath

from lxml import etree

f = StringIO(YOURS_XML)
tree = etree.parse(f)

creatives_node = tree.xpath('/Creatives')

answered Jun 7, 2017 at 5:20

Tomasz Adamczyk

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