XML：从名称空间生成带有前缀的标记

Question

我需要使用表示名称空间的不同前缀生成XML：

例如，我有以下名称空间列表：

class XMLNamespaces:
   empty="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2" 
   cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2" 
   cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2" 
   ccts="urn:un:unece:uncefact:documentation:2" 
   ds="http://www.w3.org/2000/09/xmldsig#" 
   ext="urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2" 
   qdt="urn:oasis:names:specification:ubl:schema:xsd:QualifiedDatatypes-2" 
   sac="urn:sunat:names:specification:ubl:peru:schema:xsd:SunatAggregateComponents-1" 
   udt="urn:un:unece:uncefact:data:specification:UnqualifiedDataTypesSchemaModule:2" 
   xsi="http://www.w3.org/2001/XMLSchema-instance"
# create XML 

NSMAP={None:XMLNamespaces.empty, 'cac':XMLNamespaces.cac, 'cbc':XMLNamespaces.cbc,
        'ccts':XMLNamespaces.ccts, 'ds':XMLNamespaces.ds, 'ext':XMLNamespaces.ext,
        'qdt':XMLNamespaces.qdt, 'sac':XMLNamespaces.sac, 'udt':XMLNamespaces.udt,
        'xsi':XMLNamespaces.xsi}

我想生成这个结构：

只有发票标签具有完整的名称空间。

<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2" 
xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2" 
xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2" 
xmlns:ccts="urn:un:unece:uncefact:documentation:2" 
xmlns:ds="http://www.w3.org/2000/09/xmldsig#" 
xmlns:ext="urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2" 
xmlns:qdt="urn:oasis:names:specification:ubl:schema:xsd:QualifiedDatatypes-2" 
xmlns:sac="urn:sunat:names:specification:ubl:peru:schema:xsd:SunatAggregateComponents-1" 
xmlns:udt="urn:un:unece:uncefact:data:specification:UnqualifiedDataTypesSchemaModule:2" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <ext:UBLExtensions>
     <ext:UBLExtension>
         <ext:ExtensionContent>
            <sac:AdditionalInformation>
            </sac:AdditionalInformation>
         </ext:ExtensionContent>
     </ext:UBLExtension>
</Invoice>

我的代码：

from lxml import etree
from lxml.etree import Element, SubElement, QName, tostring

class XMLNamespaces:
   empty="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2" 
   cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2" 
   cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2" 
   ccts="urn:un:unece:uncefact:documentation:2" 
   ds="http://www.w3.org/2000/09/xmldsig#" 
   ext="urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2" 
   qdt="urn:oasis:names:specification:ubl:schema:xsd:QualifiedDatatypes-2" 
   sac="urn:sunat:names:specification:ubl:peru:schema:xsd:SunatAggregateComponents-1" 
   udt="urn:un:unece:uncefact:data:specification:UnqualifiedDataTypesSchemaModule:2" 
   xsi="http://www.w3.org/2001/XMLSchema-instance"


NSMAP={None:XMLNamespaces.empty, 'cac':XMLNamespaces.cac, 'cbc':XMLNamespaces.cbc,
        'ccts':XMLNamespaces.ccts, 'ds':XMLNamespaces.ds, 'ext':XMLNamespaces.ext,
        'qdt':XMLNamespaces.qdt, 'sac':XMLNamespaces.sac, 'udt':XMLNamespaces.udt,
        'xsi':XMLNamespaces.xsi}


invoice = etree.Element("Invoice", nsmap=NSMAP) # lxml only!
ublextensions = etree.SubElement(invoice, "UBLExtensions", nsmap=NSMAP['ext'])

print(etree.tostring(invoice, pretty_print=True))

但它的回报是：

File "xml-building.py", line 27, in <module>
    ublextensions = etree.SubElement(invoice, "UBLExtensions", nsmap=NSMAP['ext'])
  File "src\lxml\etree.pyx", line 3135, in lxml.etree.SubElement
  File "src\lxml\apihelpers.pxi", line 199, in lxml.etree._makeSubElement
  File "src\lxml\apihelpers.pxi", line 193, in lxml.etree._makeSubElement
  File "src\lxml\apihelpers.pxi", line 213, in lxml.etree._setNodeNamespaces
  File "src\lxml\apihelpers.pxi", line 274, in lxml.etree._iter_nsmap
TypeError: 'in <string>' requires string as left operand, not NoneType

Answer 1

您不需要在子元素中添加nsmap。删除该名称，并在每个元素的id之前的花括号中添加所需的名称空间（请参见下文，我使用了一个额外的字典）。它将根据您的需要工作：

from lxml import etree
from lxml.etree import Element, SubElement, QName, tostring

class XMLNamespaces:
   empty="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2"
   cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2"
   cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2"
   ccts="urn:un:unece:uncefact:documentation:2"
   ds="http://www.w3.org/2000/09/xmldsig#"
   ext="urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2"
   qdt="urn:oasis:names:specification:ubl:schema:xsd:QualifiedDatatypes-2"
   sac="urn:sunat:names:specification:ubl:peru:schema:xsd:SunatAggregateComponents-1"
   udt="urn:un:unece:uncefact:data:specification:UnqualifiedDataTypesSchemaModule:2"
   xsi="http://www.w3.org/2001/XMLSchema-instance"

NSMAP={None:XMLNamespaces.empty, 'cac':XMLNamespaces.cac, 'cbc':XMLNamespaces.cbc,
        'ccts':XMLNamespaces.ccts, 'ds':XMLNamespaces.ds, 'ext':XMLNamespaces.ext,
        'qdt':XMLNamespaces.qdt, 'sac':XMLNamespaces.sac, 'udt':XMLNamespaces.udt,
        'xsi':XMLNamespaces.xsi}

ns = {k:'{' + v + '}' for k,v in NSMAP.items()}

invoice = etree.Element("Invoice", nsmap=NSMAP) # lxml only!
ublextensions = etree.SubElement(invoice, f"{ns['ext']}UBLExtensions")
ublextension = etree.SubElement(ublextensions, f"{ns['ext']}UBLExtension")
extcontent = etree.SubElement(ublextension, f"{ns['ext']}ExtensionContent")
addinfo = etree.SubElement(extcontent, f"{ns['sac']}AdditionalInformation")

print(etree.tostring(invoice, pretty_print=True).decode('ascii'))

结果:

<Invoice xmlns="urn:oasis:names:specification:ubl:schema:xsd:Invoice-2"
 xmlns:cac="urn:oasis:names:specification:ubl:schema:xsd:CommonAggregateComponents-2"
 xmlns:cbc="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponents-2"
 xmlns:ccts="urn:un:unece:uncefact:documentation:2"
 xmlns:ds="http://www.w3.org/2000/09/xmldsig#"
 xmlns:ext="urn:oasis:names:specification:ubl:schema:xsd:CommonExtensionComponents-2"
 xmlns:qdt="urn:oasis:names:specification:ubl:schema:xsd:QualifiedDatatypes-2"
 xmlns:sac="urn:sunat:names:specification:ubl:peru:schema:xsd:SunatAggregateComponents-1"
 xmlns:udt="urn:un:unece:uncefact:data:specification:UnqualifiedDataTypesSchemaModule:2"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  <ext:UBLExtensions>
    <ext:UBLExtension>
      <ext:ExtensionContent>
        <sac:AdditionalInformation/>
      </ext:ExtensionContent>
    </ext:UBLExtension>
  </ext:UBLExtensions>
</Invoice>