如何提取XML中无xml:lang属性的<sample>元素内容？

你的XML内容 #

<components version="1.0.0">
    <component type="foo">
        <sample>Foo</sample>
        <sample xml:lang="a">abc</sample>
        <sample xml:lang="b">efj</sample>
    </component>
</components>

现有Python解析代码 #

from lxml import etree

def parse(path: str):
    return etree.parse(path)

def components(path: str) -> list:
    components = parse(path).xpath("/components/component")
    return list(components)

def sample(path: str) -> str:
    sample = components(path)[0].find("sample").text
    return str(sample)

path = "test.xml"
print(sample(path))

实现方法 #

方法一：用XPath直接筛选（推荐） #

利用XPath的条件表达式，直接定位没有xml:lang属性的<sample>元素，代码简洁高效：

from lxml import etree

def parse(path: str):
    return etree.parse(path)

def get_sample_without_lang(path: str) -> str:
    # XPath语法：not(@xml:lang) 表示元素不存在xml:lang属性
    target_sample = parse(path).xpath("/components/component/sample[not(@xml:lang)]")[0]
    return target_sample.text

path = "test.xml"
print(get_sample_without_lang(path))  # 输出：Foo

方法二：遍历元素检查属性 #

如果需要遍历所有<sample>元素再判断，可以通过元素的attrib字典或get()方法检查属性是否存在：

from lxml import etree

def parse(path: str):
    return etree.parse(path)

def components(path: str) -> list:
    components = parse(path).xpath("/components/component")
    return list(components)

def get_sample_without_lang(path: str) -> str:
    target_component = components(path)[0]
    # 遍历所有<sample>子元素
    for sample_elem in target_component.findall("sample"):
        # 方式1：检查attrib字典中是否不含xml:lang
        if "xml:lang" not in sample_elem.attrib:
            return sample_elem.text
        # 方式2：用get方法，属性不存在时返回None
        # if sample_elem.get("xml:lang") is None:
        #     return sample_elem.text
    return ""  # 未找到符合条件的元素时返回空字符串

path = "test.xml"
print(get_sample_without_lang(path))  # 输出：Foo

内容的提问来源于stack exchange，提问作者user22990699