Parsing XML with namespace in Python via 'ElementTree'

Question

I have the following XML which I want to parse using Python's `ElementTree`: ``` basketball league a group of sports teams that compete against each other in Basketball ``` I want to find all `owl:Class` tags and then extract the value of all `rdfs:label` instances inside them. I am using the following code: ``` tree = ET.parse("filename") root = tree.getroot() root.findall('owl:Class') ``` Because of the namespace, I am getting the following error. ``` SyntaxError: prefix 'owl' not found in prefix map ``` I tried reading the documen…

Accepted Answer

You need to give the `.find()`, `findall()` and `iterfind()` methods an explicit namespace dictionary:

```
namespaces = {'owl': 'http://www.w3.org/2002/07/owl#'} # add more as needed

root.findall('owl:Class', namespaces)
```

Prefixes are only looked up in the `namespaces` parameter you pass in. This means you can use any namespace prefix you like; the API splits off the `owl:` part, looks up the corresponding namespace URL in the `namespaces` dictionary, then changes the search to look for the XPath expression `{http://www.w3.org/2002/07/owl}Class` instead. You can use the same syntax yourself too of course:

```
root.findall('{http://www.w3.org/2002/07/owl#}Class')
```

Also see the Parsing XML with Namespaces section of the ElementTree documentation.

If you can switch to the `lxml` library things are better; that library supports the same ElementTree API, but collects namespaces for you in `.nsmap` attribute on elements and generally has superior namespaces support.

Parsing XML with namespace in Python via 'ElementTree'

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