在 python lxml 中查找前缀标签的技巧？

Question

我正在尝试使用 lxml 的 ElementTree etree 在我的 xml 文档中查找特定标签。 该标签如下所示：

<text:ageInformation>
    <text:statedAge>12</text:statedAge>
</text:ageInformation>

我希望使用 etree.find('text:statedAge')，但该方法不喜欢 'text' 前缀。 它提到我应该将“文本”添加到前缀映射中，但我不确定如何做到这一点。有什么建议吗？

编辑： 我希望能够写入 hr4e 前缀标签。 以下是该文档的重要部分：

<?xml version="1.0" encoding="utf-8"?>
<greenCCD xmlns="AlschulerAssociates::GreenCDA" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hr4e="hr4e::patientdata" xsi:schemaLocation="AlschulerAssociates::GreenCDA green_ccd.xsd">
  <header>
    <documentID root="18c41e51-5f4d-4d15-993e-2a932fed720a" />
    <title>Health Records for Everyone Continuity of Care Document</title>
    <version>
  <number>1</number>
</version>
<confidentiality codeSystem="2.16.840.1.113883.5.25" code="N" />
<documentTimestamp value="201105300211+0800" />
<personalInformation>
  <patientInformation>
    <personID root="2.16.840.1.113883.3.881.PI13023911" />
    <personAddress>
      <streetAddressLine nullFlavor="NI" />
      <city>Santa Cruz</city>
      <state nullFlavor="NI" />
      <postalCode nullFlavor="NI" />
    </personAddress>
    <personPhone nullFlavor="NI" />
    <personInformation>
      <personName>
        <given>Benjamin</given>
        <family>Keidan</family>
      </personName>
      <gender codeSystem="2.16.840.1.113883.5.1" code="M" />
      <personDateOfBirth value="NI" />
      <hr4e:ageInformation>
        <hr4e:statedAge>9424</hr4e:statedAge>
        <hr4e:estimatedAge>0912</hr4e:estimatedAge>
        <hr4e:yearInSchool>1</hr4e:yearInSchool>
        <hr4e:statusInSchool>attending</hr4e:statusInSchool>
      </hr4e:ageInformation>
    </personInformation>
    <hr4e:livingSituation>
      <hr4e:homeVillage>Putney</hr4e:homeVillage>
      <hr4e:tribe>Oromo</hr4e:tribe>
    </hr4e:livingSituation>
  </patientInformation>
</personalInformation>

Answer 1

命名空间前缀必须在 XML 文档中声明（映射到 URI）。然后您可以使用 {URI}localname 表示法 来查找 text:statedAge 和其他元素。像这样：

from lxml import etree

XML = """
<root xmlns:text="http://example.com">
 <text:ageInformation>
   <text:statedAge>12</text:statedAge>
 </text:ageInformation>
</root>"""

root = etree.fromstring(XML)

ageinfo = root.find("{http://example.com}ageInformation")
age = ageinfo.find("{http://example.com}statedAge")
print age.text

这将打印“12”。

另一种方法：

ageinfo = root.find("text:ageInformation",
                    namespaces={"text": "http://example.com"})
age = ageinfo.find("text:statedAge",
                   namespaces={"text": "http://example.com"})
print age.text

您还可以使用 XPath：

age = root.xpath("//text:statedAge",
                 namespaces={"text": "http://example.com"})[0]
print age.text

Answer 2

我最终不得不使用嵌套前缀：

from lxml import etree

XML = """
<greenCCD xmlns="AlschulerAssociates::GreenCDA" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:hr4e="hr4e::patientdata"  xsi:schemaLocation="AlschulerAssociates::GreenCDA green_ccd.xsd">
<personInformation>
 <hr4e:ageInformation>
   <hr4e:statedAge>12</hr4e:statedAge>
 </hr4e:ageInformation>
</personInformation>
</greenCCD>"""

root = etree.fromstring(XML)
#root = etree.parse("hr4e_patient.xml")

ageinfo = root.find("{AlschulerAssociates::GreenCDA}personInformation/{hr4e::patientdata}ageInformation")
age = ageinfo.find("{hr4e::patientdata}statedAge")
print age.text