How to select data for xml Element with specific attribute value?

Question

Given:

<foo>
 <bar key="true">text1</bar>
 <bar key="false">text2</bar>
 <bar key="true">text3</bar>
 <bar key="true">text4</bar>
</foo>

I want to get the text for the bar element where the key attribute = "false".

My application is Python 2.5.5 on GAE. The XML is not true xml, but I can load it as an ElementTree and fetch data normally.

Code example:

result = urllib2.urlopen(url).read()
xml = ElementTree.fromstring(result)
str = xml.find("./bar").attrib['key']

to get the first value. I've tried various xpath queries that I think should work but I've obviously got the syntax wrong.

UPDATE:

str = xml.findtext("./bar[@key='false']")

Throws error:

  File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/xml/etree/ElementPath.py", line 93, in __init__
    "expected path separator (%s)" % (op or tag)
SyntaxError: expected path separator ([)

findtext seems like an odd way of using xpath, especially considering stackoverflow.com/questions/8692/how-to-use-xpath-in-python shows a different method. — Andrew T Finnell
– Andrew T Finnell, Commented Jan 1, 2011 at 17:06
Merydith: Please, use a full complain XPath engine like lxml and not basic ElementTree API. — user357812
– user357812, Commented Jan 1, 2011 at 17:12

Josh O'Brien · Accepted Answer · 2011-12-07 20:10:46Z

3

I might be wrong but I dont think that the "./bar[@key='false']" notation works in Python 2.5.5 (or at least not with the ElementTree that comes with it). I have observed the same problem in Python 2.6.5, but it does work in Python 2.7.1. I guess you will have to use another library or try the "experimental" GAE with Python 2.7.

edited Dec 7, 2011 at 20:10

Josh O'Brien

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answered Dec 7, 2011 at 19:45

chuckshop

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1 Comment

Nick Farina Over a year ago

Looking at the source of ElementTree as included with Python 2.5, it does seem that attribute selectors aren't supported.

Oded · Accepted Answer · 2011-01-01 15:55:42Z

2

This XPath will select the bar nodes whose key attribute is equal to false:

/foo/bar[@key='false']

If the current context node is the foo node then this will also work:

./bar[@key='false']

answered Jan 1, 2011 at 15:55

Oded

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3 Comments

Will Curran Over a year ago

I thought that was the syntax, but it returns and error (see update to original post).

Oded Over a year ago

@Will Merydith - Are you sure the current context node is foo? Try the first example.

Will Curran Over a year ago

I'm pretty certain because the rest of my code is working (grabbing lots of data from this xml). If I try the first example I get the error: "SyntaxError: cannot use absolute path on element"

Community · Accepted Answer · 2017-05-23 12:15:15Z

1

Based on the answer here, the XPath selector functionality was not implemented in ElementTree until version 1.3, which ships with Python 2.7, as @cdemers said.

edited May 23, 2017 at 12:15

CommunityBot

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answered Nov 27, 2012 at 20:55

Ken Bellows

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Comments

aaviram · Accepted Answer · 2015-11-19 15:50:21Z

0

"[@attrib]" which you are using is only introduced in ElementTree 1.3: http://effbot.org/zone/element-xpath.htm

which was introduced only to Python 2.7:

https://docs.python.org/2/library/xml.etree.elementtree.html

As other people here mentioned, you need to get this attribute differently or upgrade Python for that code to work.

answered Nov 19, 2015 at 15:50

aaviram

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