Python和libxml2:如何使用XPATH在xml节点中进行迭代 [英] Python and libxml2: how to iterate in xml nodes with XPATH
问题描述
我在从XML树中检索信息时遇到问题.
I have a problem with retrieving information from a XML tree.
我的XML具有以下形状:
My XML has this shape:
<?xml version="1.0"?>
<records xmlns="http://www.mysyte.com/foo">
<record>
<id>first</id>
<name>john</name>
<papers>
<paper>john_1</paper>
<paper>john_2</paper>
</papers>
</record>
<record>
<id>second</id>
<name>mike</name>
<papers>
<paper>mike_a</paper>
<paper>mike_b</paper>
</papers>
</record>
<record>
<id>third</id>
<name>albert</name>
<papers>
<paper>paper of al</paper>
<paper>other paper</paper>
</papers>
</record>
</records>
我想要做的是提取数据元组,如下所示:
What I want to do is to extract tuples of data like the follow:
[{'code': 'first', 'name': 'john'},
{'code': 'second', 'name': 'mike'},
{'code': 'third', 'name': 'albert'}]
现在,我编写了以下python代码:
Now I wrote this python code:
try:
doc = libxml2.parseDoc(xml)
except (libxml2.parserError, TypeError):
print "Problems loading XML"
ctxt = doc.xpathNewContext()
ctxt.xpathRegisterNs("pre", "http://www.mysyte.com/foo")
record_nodes = ctxt.xpathEval('/pre:records/pre:record')
for record_node in record_nodes:
id = record_node.xpathEval('id')[0].content
name = record_node.xpathEval('name')[0].content
ret_list.append({'code': id, 'name': name})
我的问题是我没有任何结果,给人的印象是,当我在节点上进行迭代时,我在XPATH上做错了事.
My problem is that I don't have any result and I have the impression that I'm doing something wrong with the XPATH when I iterate on the nodes.
我还尝试使用这些XPATH作为ID和名称:
I also tried with these XPATHs for the id and the name:
/id
/name
/record/id
/record/name
/pre:id
/pre:name
依此类推,但有任何结果(顺便说一句,如果我在子查询中使用前缀,则会出错).
and so on, but with any result (BTW if I use the prefix in the sub queries I have an error).
有什么主意吗?
推荐答案
这是一个建议.请注意setContextNode()
方法:
Here is a suggestion. Note the setContextNode()
method:
import libxml2
xml = "test.xml"
doc = libxml2.parseFile(xml)
ctxt = doc.xpathNewContext()
ctxt.xpathRegisterNs("pre","http://www.mysyte.com/foo")
ret_list = []
record_nodes = ctxt.xpathEval('/pre:records/pre:record')
for node in record_nodes:
ctxt.setContextNode(node)
_id = ctxt.xpathEval('pre:id')[0].content
name = ctxt.xpathEval('pre:name')[0].content
ret_list.append({'code': _id, 'name': name})
print ret_list
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