Parsing XML with namespaces using ElementTree in Python

Question

I have an xml, small part of it looks like this:

Answer 1

From what I gather, it has something to do with the namespace recognition in ET.

from here http://effbot.org/zone/element-namespaces.htm

When you save an Element tree to XML, the standard Element serializer generates unique prefixes for all URI:s that appear in the tree. The prefixes usually have the form “ns” followed by a number. For example, the above elements might be serialized with the prefix ns0 for “http://www.w3.org/1999/xhtml” and ns1 for “http://effbot.org/namespace/letters”.

If you want to use specific prefixes, you can add prefix/uri mappings to a global table in the ElementTree module. In 1.3 and later, you do this by calling the register_namespace function. In earlier versions, you can access the internal table directly:

ElementTree 1.3

ET.register_namespace(prefix, uri)

ElementTree 1.2 (Python 2.5)

ET._namespace_map[uri] = prefix

Note the argument order; the function takes the prefix first, while the raw dictionary maps from URI:s to prefixes.

Answer 2

This snippet from your question,

for a in root.findall('{urn:com:xml:data}image'):
    print a.attrib

does not output anything because it only looks for direct {urn:com:xml:data}image children of the root of the tree.

This slightly modified code,

for a in root.findall('.//{urn:com:xml:data}image'):
    print a.attrib

will print {'imageId': '1'} because it uses .//, which selects matching subelements on all levels.

Reference: https://docs.python.org/2/library/xml.etree.elementtree.html#supported-xpath-syntax.

---

It is a bit annoying that ElementTree does not just retain the original namespace prefixes by default, but keep in mind that it is not the prefixes that matter anyway. The register_namespace() function can be used to set the wanted prefix when serializing the XML. The function does not have any effect on parsing or searching.