Python XML ElementTree不能迭代()、find()或findall()

Question

我可以创建一个xml文件并循环执行根打印，但root.iter('tag')、root.find('tag')和root.findall('tag')将不起作用。

以下是XML:的示例

<?xml version='1.0' encoding='UTF-8'?>
<cpe-list xmlns:config="http://scap.nist.gov/schema/configuration/0.1" xmlns="http://cpe.mitre.org/dictionary/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:scap-core="http://scap.nist.gov/schema/scap-core/0.3" xmlns:cpe-23="http://scap.nist.gov/schema/cpe-extension/2.3" xmlns:ns6="http://scap.nist.gov/schema/scap-core/0.1" xmlns:meta="http://scap.nist.gov/schema/cpe-dictionary-metadata/0.2" xsi:schemaLocation="http://scap.nist.gov/schema/cpe-extension/2.3 https://scap.nist.gov/schema/cpe/2.3/cpe-dictionary-extension_2.3.xsd http://cpe.mitre.org/dictionary/2.0 https://scap.nist.gov/schema/cpe/2.3/cpe-dictionary_2.3.xsd http://scap.nist.gov/schema/cpe-dictionary-metadata/0.2 https://scap.nist.gov/schema/cpe/2.1/cpe-dictionary-metadata_0.2.xsd http://scap.nist.gov/schema/scap-core/0.3 https://scap.nist.gov/schema/nvd/scap-core_0.3.xsd http://scap.nist.gov/schema/configuration/0.1 https://scap.nist.gov/schema/nvd/configuration_0.1.xsd http://scap.nist.gov/schema/scap-core/0.1 https://scap.nist.gov/schema/nvd/scap-core_0.1.xsd">
<generator>
<product_name>National Vulnerability Database (NVD)</product_name>
<product_version>4.4</product_version>
<schema_version>2.3</schema_version>
<timestamp>2021-05-21T03:50:31.204Z</timestamp>
</generator>
<cpe-item name="cpe:/a:%240.99_kindle_books_project:%240.99_kindle_books:6::~~~android~~">
<title xml:lang="en-US">$0.99 Kindle Books project $0.99 Kindle Books (aka com.kindle.books.for99) for android 6.0</title>
<references>
<reference href="https://play.google.com/store/apps/details?id=com.kindle.books.for99">Product information</reference>
<reference href="https://docs.google.com/spreadsheets/d/1t5GXwjw82SyunALVJb2w0zi3FoLRIkfGPc7AMjRF0r4/edit?pli=1#gid=1053404143">Government Advisory</reference>
</references>
<cpe-23:cpe23-item name="cpe:2.3:a:$0.99_kindle_books_project:$0.99_kindle_books:6:*:*:*:*:android:*:*"/>
</cpe-item>
<cpe-item name="cpe:/a:%40thi.ng%2fegf_project:%40thi.ng%2fegf:-::~~~node.js~~">
<title xml:lang="en-US">@thi.ng/egf Project @thi.ng/egf for Node.js</title>
<references>
<reference href="https://github.com/thi-ng/umbrella/security/advisories/GHSA-rj44-gpjc-29r7">Advisory</reference>
<reference href="https://www.npmjs.com/package/@thi.ng/egf">Version</reference>
</references>
<cpe-23:cpe23-item name="cpe:2.3:a:@thi.ng/egf_project:@thi.ng/egf:-:*:*:*:*:node.js:*:*"/>
</cpe-item>
</cpe-list>

以下Python(3.7(代码有效：

import xml.etree.ElementTree as ET
infile = open(filename, "r")
xml = infile.read()
infile.close()
parser = ET.XMLParser(encoding="utf-8")
root = ET.fromstring(xml, parser=parser)
print(root.tag)
for child in root:
print(child.tag)
Output:
{http://cpe.mitre.org/dictionary/2.0}cpe-list
{http://cpe.mitre.org/dictionary/2.0}cpe-item
{http://cpe.mitre.org/dictionary/2.0}cpe-item
{http://cpe.mitre.org/dictionary/2.0}cpe-item
{http://cpe.mitre.org/dictionary/2.0}cpe-item
...

但当我尝试时：

for item in root.iter('cpe-item')或for item in root.iter('cpe-list')，无任何循环。当我尝试for item in root.findall('cpe-item')或root.findall('cpe-list')中的项时，没有任何循环。如果我尝试item = root.find('cpe-list')，item = None。

我不经常使用XML，但这对我来说似乎太过时了，因为我有一些其他项目的示例代码，在这些代码中，XML工作得非常好。网上的许多其他例子表明，这个确切的过程是正确的。

我做错了什么？我觉得奇怪的是，当我print(root.tag)或print(child.tag)时，标签打印之前有一些东西。我不知道为什么会这样。

Answer 1

您正被名称空间所困扰。关于它已经写了很多文章，从这里开始可能是一个好地方。

至于您的具体示例，tl；博士将完全无视它们。例如：

for item in root.findall('.//{*}cpe-item'):
print(item.tag)

另一种选择是咬紧牙关并声明名称空间：

ns = {"xx":"http://cpe.mitre.org/dictionary/2.0"}
for item in root.findall('.//xx:cpe-item', ns):
print(item.tag)

输出为

{http://cpe.mitre.org/dictionary/2.0}cpe-item
{http://cpe.mitre.org/dictionary/2.0}cpe-item