如何獲取具有特定標簽和屬性的子元素的 xml 元素

Question

我想找到具有某些子元素的 xml 元素。 子元素需要有一個給定的標簽和一個設置為特定值的屬性。

舉一個具體的例子（根據官方文檔）。 我想找到所有具有屬性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)

我沒有成功的嘗試：

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

這都給了：

SyntaxError：無效謂詞

---

以下解決方案顯然是錯誤的，因為發現了太多元素：

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

其中countries4包含所有具有屬性name="Austria"的元素，但包括partner元素。 countries5包含所有具有任何相鄰元素作為子元素的元素。

Answer 1

我想找到所有具有屬性 name="Austria" 的子元素鄰居的國家元素

見下文

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