如何获取具有特定标签和属性的子元素的 xml 元素

Question

我想找到具有某些子元素的 xml 元素。 子元素需要有一个给定的标签和一个设置为特定值的属性。

举一个具体的例子（根据官方文档）。 我想找到所有具有属性name="Austria"的子元素neighbor的country元素：

import xml.etree.ElementTree as ET

data = """<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <neighbor name="Malaysia" direction="N"/>
        <partner name="Austria"/>
    </country>
    <country name="Panama">
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
</data>
"""

root = ET.fromstring(data)

我没有成功的尝试：

countries1 = root.findall('.//country[neighbor@name="Austria"]')
countries2 = root.findall('.//country[neighbor][@name="Austria"]')
countries3 = root.findall('.//country[neighbor[@name="Austria"]]')

这都给了：

SyntaxError：无效谓词

---

以下解决方案显然是错误的，因为发现了太多元素：

countries4 = root.findall('.//country/*[@name="Austria"]')
countries5 = root.findall('.//country/[neighbor]')

其中countries4包含所有具有属性name="Austria"的元素，但包括partner元素。 countries5包含所有具有任何相邻元素作为子元素的元素。

Answer 1

我想找到所有具有属性 name="Austria" 的子元素邻居的国家元素

见下文

import xml.etree.ElementTree as ET

data = """<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <neighbor name="Malaysia" direction="N"/>
        <partner name="Austria"/>
    </country>
    <country name="Panama">
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
</data>
"""

root = ET.fromstring(data)
countries_with_austria_as_neighbor = [c.attrib['name'] for c in root.findall('.//country') if
                                      'Austria' in [n.attrib['name'] for n in c.findall('neighbor')]]
print(countries_with_austria_as_neighbor)

output

['Liechtenstein']

Answer 2

import xml.etree.ElementTree as ET

data = """<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <neighbor name="Malaysia" direction="N"/>
        <partner name="Austria"/>
    </country>
    <country name="Panama">
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
    <country name="Liechtenstein">
        <neighbor name="Austria" direction="dummy"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    
</data>
"""

root = ET.fromstring(data)
for x in root.findall(".//country/neighbor[@name='Austria']"):
    print(x.attrib)

Output：

{'name': 'Austria', 'direction': 'E'}
{'name': 'Austria', 'direction': 'dummy'}

// : Selects all subelements, on all levels beneath the current element. For example, .//egg selects all egg elements in the entire tree. Selects all subelements, on all levels beneath the current element. For example, .//egg selects all egg elements in the entire tree.

[@attrib='value'] ： Selects all elements for which the given attribute has the given value. The value cannot contain quotes Selects all elements for which the given attribute has the given value. The value cannot contain quotes

for x in root.find('.'):
    if x[0].attrib['name'] == 'Austria':
                   print(x.attrib['name']) 

Output： Liechtenstein