如何使用lxml（节点与其他命名空间）添加名称空间前缀？

Question

I need to get this xml:

<s:Envelope xmlns:a="http://www.w3.org/2005/08/addressing" xmlns:s="http://www.w3.or/2003/05/soap-envelope">
   <s:Header>
       <a:Action s:mustUnderstand="1">Action</a:Action>
   </s:Header>
</s:Envelope>

As I understand < Action > node and it's attribute "mustUnderstand" is under different namespaces. What I achieved now:

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

class XMLNamespaces:
   s = 'http://www.w3.org/2003/05/soap-envelope'
   a = 'http://www.w3.org/2005/08/addressing'


root = Element(QName(XMLNamespaces.s, 'Envelope'), nsmap={'s':XMLNamespaces.s, 'a':XMLNamespaces.a})

header = SubElement(root, QName(XMLNamespaces.s, 'Header'))
action  = SubElement(header, QName(XMLNamespaces.a, 'Action'))
action.attrib['mustUnderstand'] = "1"
action.text = 'Action'

print tostring(root, pretty_print=True)

And result:

<s:Envelope xmlns:a="http://www.w3.org/2005/08/addressing" xmlns:s="http://www.w3.org/2003/05/soap-envelope">
   <s:Header>
      <a:Action mustUnderstand="1">http://schemas.xmlsoap.org/ws/2004/09/transfer/Create</a:Action>
    </s:Header>
</s:Envelope>

As we can see, no namespace prefix in front of "mustUnderstand" attribute. So is it possible to get " s: mustUnderstand" with lxml? if yes, then how?

Answer 1

只需使用QName，就像使用元素名称一样：

action.attrib[QName(XMLNamespaces.s, 'mustUnderstand')] = "1"

Answer 2

Also if you want to create all attributes in single SubElement sentence, you can exploit its feature that attributes are just a dictionary:

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

class XMLNamespaces:
   s = 'http://www.w3.org/2003/05/soap-envelope'
   a = 'http://www.w3.org/2005/08/addressing'

root = Element(QName(XMLNamespaces.s, 'Envelope'), nsmap={'s':XMLNamespaces.s, 'a':XMLNamespaces.a})

header = SubElement(root, QName(XMLNamespaces.s, 'Header'))
action  = SubElement(header, QName(XMLNamespaces.a, 'Action'), attrib={
    'notUnderstand':'1',
    QName(XMLNamespaces.s, 'mustUnderstand'):'1'
    })

print (tounicode(root, pretty_print=True))

The result is:

<s:Envelope xmlns:a="http://www.w3.org/2005/08/addressing" xmlns:s="http://www.w3.org/2003/05/soap-envelope">
  <s:Header>
    <a:Action notUnderstand="1" s:mustUnderstand="1"/>
  </s:Header>
</s:Envelope>