Why does this xpath expression return an empty list?

Question

I'm trying to parse this XML. It's a YouTube feed. I'm working based on code in the tutorial. I want to get all the entry nodes that are nested under the feed.

from lxml import etree
root = etree.fromstring(text)
entries = root.xpath("/feed/entry")
print entries

For some reason entries is an empty list. Why?

@NilsWerner I updated the link to point to pretty-printed XML. — mpenkov
– mpenkov, Commented Aug 22, 2013 at 5:49

Nils Werner · Accepted Answer · 2013-08-21 11:35:31Z

4

feed and all its children are actually in the http://www.w3.org/2005/Atom namespace. You need to tell your xpath that:

entries = root.xpath("/atom:feed/atom:entry", 
                     namespaces={'atom': 'http://www.w3.org/2005/Atom'})

or, if you want to change the default empty namespace:

entries = root.xpath("/feed/entry", 
                     namespaces={None: 'http://www.w3.org/2005/Atom'})

or, if you don't want to use shorthandles at all:

entries = root.xpath("/{http://www.w3.org/2005/Atom}feed/{http://www.w3.org/2005/Atom}entry")

To my knowledge the "local namespace" is implicitly assumed for the node you're working with so that operations on children in the same namespace do not require you to set it again. So you should be able to do something along the lines of:

feed = root.find("/atom:feed",
                     namespaces={'atom': 'http://www.w3.org/2005/Atom'})

title = feed.xpath("title")
entries = feed.xpath("entries")
# etc...

edited Aug 21, 2013 at 11:35

answered Aug 21, 2013 at 11:20

Nils Werner

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6 Comments

user1593705 Over a year ago

i think you could do it only if your are the author of this XML file to drop this namespace

Nils Werner Over a year ago

You should not "drop the namespace" as there is a reason why Atom feeds are using it. I've added a few more examples that could make your life easier.

BartoszKP Over a year ago

Some XPATH versions allow specifying "*" for any namespace if I recall correctly?

Nils Werner Over a year ago

You can use *[local-name()='feed'] to match an element feed of any namespace. That is considered to be bad practice though.

Michael Kay Over a year ago

@misha Is there any way to avoid specifying the prefix? Yes, use XPath 2.0. But that's not easy from Python.

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BartoszKP · Accepted Answer · 2013-08-21 11:16:59Z

1

It's because of the namespace in the XML. Here is an explanation: http://www.edankert.com/defaultnamespaces.html#Conclusion.

answered Aug 21, 2013 at 11:16

BartoszKP

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