如何在Python中通过标记查找XML元素

Question

我很难识别Python中正确的元素。我真正想看到的是recently-used.xbel.中最新访问的文件因此，我想对每个文件进行迭代，以找到具有最新的修改的或最新的访问的文件--这是XML文件的样子。

<?xml version="1.0" encoding="UTF-8"?>
<xbel version="1.0"
      xmlns:bookmark="http://www.freedesktop.org/standards/desktop-bookmarks"
      xmlns:mime="http://www.freedesktop.org/standards/shared-mime-info"
>
  <bookmark href="file:///tmp/google-chrome-stable_current_amd64.deb" added="2021-09-14T12:09:05Z" modified="2021-09-14T12:09:05Z" visited="2021-09-15T09:12:13Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="application/vnd.debian.binary-package"/>
        <bookmark:applications>
          <bookmark:application name="Firefox" exec="&apos;firefox %u&apos;" modified="2021-09-14T12:09:05Z" count="1"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///home/test/Git/testprog" added="2021-09-15T09:12:13Z" modified="2021-09-15T09:12:13Z" visited="2021-09-15T09:12:13Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="inode/directory"/>
        <bookmark:applications>
          <bookmark:application name="code" exec="&apos;code %u&apos;" modified="2021-09-15T09:12:13Z" count="1"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///home/test/.local/share/recently-used.xbel" added="2021-09-15T09:51:57Z" modified="2021-09-15T09:51:57Z" visited="2021-09-15T09:51:57Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="application/x-xbel"/>
        <bookmark:applications>
          <bookmark:application name="code" exec="&apos;code %u&apos;" modified="2021-09-15T09:51:57Z" count="1"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///tmp/slack-desktop-4.19.2-amd64.deb" added="2021-09-15T11:45:49Z" modified="2021-09-15T11:45:49Z" visited="2021-09-16T13:26:26Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="application/vnd.debian.binary-package"/>
        <bookmark:applications>
          <bookmark:application name="Firefox" exec="&apos;firefox %u&apos;" modified="2021-09-15T11:45:49Z" count="1"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///home/test/Downloads/google-chrome-stable_current_amd64.deb" added="2021-09-15T11:52:39Z" modified="2021-09-15T11:52:39Z" visited="2021-09-16T13:26:26Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="application/vnd.debian.binary-package"/>
        <bookmark:applications>
          <bookmark:application name="Firefox" exec="&apos;firefox %u&apos;" modified="2021-09-15T11:52:39Z" count="1"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///home/test/Documents/libretest" added="2021-09-15T11:58:53Z" modified="2021-09-15T11:58:53Z" visited="2021-09-16T13:26:26Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="application/octet-stream"/>
        <bookmark:applications>
          <bookmark:application name="LibreOffice 6.4" exec="&apos;soffice %u&apos;" modified="2021-09-15T11:58:53Z" count="1"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///home/test/Documents/libretest.odt" added="2021-09-15T11:58:53Z" modified="2021-09-15T15:42:04Z" visited="2021-09-16T13:26:26Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="application/vnd.oasis.opendocument.text"/>
        <bookmark:applications>
          <bookmark:application name="LibreOffice 6.4" exec="&apos;soffice %u&apos;" modified="2021-09-15T15:42:04Z" count="12"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
  <bookmark href="file:///home/test/Git/node-socket" added="2021-09-16T13:26:25Z" modified="2021-09-16T13:26:49Z" visited="2021-09-16T13:26:26Z">
    <info>
      <metadata owner="http://freedesktop.org">
        <mime:mime-type type="inode/directory"/>
        <bookmark:applications>
          <bookmark:application name="code" exec="&apos;code %u&apos;" modified="2021-09-16T13:26:49Z" count="2"/>
        </bookmark:applications>
      </metadata>
    </info>
  </bookmark>
</xbel>

在我的代码中，我试图访问bookmark:applications，但没有成功。

    home = str(Path.home())
    root = ET.parse(home + '/.local/share/recently-used.xbel').getroot()
    print(root)
    print('lower')
    for bookmark in root.iter('bookmark'):
        print(bookmark)
        for applications in bookmark.find('applications'):
            print(applications)

访问bookmark:applications和查找上次访问的正确方法是什么？

Answer 1

这对于访问书签非常有用:应用程序和dataframe将帮助您获得最新访问/修改的带有应用程序名称的书签。

import xml.etree.ElementTree as ET
import pandas as pd

root = ET.parse('/content/sample.xml').getroot()
lst = []

for bookmark in bookmarklist:
  bookmark_lst = []
  print(bookmark.attrib)
  bookmark_lst.append(bookmark.attrib['href'])
  bookmark_lst.append(bookmark.attrib['modified'])
  bookmark_lst.append(bookmark.attrib['visited'])
  for ele in list(bookmark.iter()) :
    if 'application' in ele.tag:
      if 'name' in ele.attrib:
        bookmark_lst.append(ele.attrib['name'])
  lst.append(bookmark_lst)

df = pd.DataFrame(lst,columns ['href','modified','visited','application_name'])

df['modified'] = pd.to_datetime(df['modified'])
df['visited'] = pd.to_datetime(df['visited'])

least_recent_date = df['visited'].min()
most_recent_date = df['visited'].max()

Answer 2

from lxml import etree

NS = {"n": "http://www.freedesktop.org/standards/desktop-bookmarks"}

root = etree.parse("book.xml")
bookmarks = root.xpath("//bookmark")
most_recent_bookmark = max(
    bookmarks,
    key=lambda bmark: bmark.xpath(
        "string(.//n:application/@modified)",
        namespaces=NS,
    ),
)

print("Most recent href: " + most_recent_bookmark.xpath("string(@href)"))
print(
    "Most recent modified: "
    + most_recent_bookmark.xpath("string(.//n:application/@modified)", namespaces=NS)
)

输出：

Most recent href: file:///home/test/Git/node-socket
Most recent modified: 2021-09-16T13:26:49Z

您遇到的问题是，如何在原始xml中指定由bookmark:表示的名称空间，在代码示例中指定n:表示的名称空间。xpath()、find()和findall()函数都允许您提供名称空间字典。

https://docs.python.org/3/library/xml.etree.elementtree.html#xml.etree.ElementTree.Element.findall

如果如您所说的，名称空间可能会发生变化，则可以使用XPath .//*[local-name() = 'application']/@modified代替没有命名空间参数的.//n:application/@modified。(但是，看到生产者任意更改名称空间，我会感到惊讶，因为它只是要求所有消耗数据的东西都中断。url与"application“一样是节点名称的一部分。)