lxml - XML Document with multiple NameSpaces

Question

is it possible to construct a XML as this one using lxml?

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns0="http://xmlns.CLT.com/consume/ENTBUS" xmlns:ns1="http://xmlns.CLT.com/Core/ENTBUS" xmlns:ns2="http://xmlns.CLT.com/output/EBO">
   <soapenv:Header/>
   <soapenv:Body>
      <ns0:ConsumptionRequestENTBUS>
         <ns1:ENTBUSHeader>
            <ns1:ENTBUSID>1</ns1:ENTBUSID>
         </ns1:ENTBUSHeader>
         <ns0:Zone>
            <ns2:Consumption>
               <ns2:BusCode>1</ns2:BusCode>
            </ns2:Consumption>
         </ns0:Zone>
      </ns0:ConsumptionRequestENTBUS>
   </soapenv:Body>
</soapenv:Envelope>

I tried building the root element as below but it fails. And almost every element needs to be namespace referenced.

>>> from lxml import etree
>>> root = etree.Element("soapenv:Envelope")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "lxml.etree.pyx", line 2811, in lxml.etree.Element (src\lxml\lxml.etree.c:65389)
  File "apihelpers.pxi", line 103, in lxml.etree._makeElement (src\lxml\lxml.etree.c:13898)
  File "apihelpers.pxi", line 1575, in lxml.etree._tagValidOrRaise (src\lxml\lxml.etree.c:27955)
ValueError: Invalid tag name u'soapenv:Envelope'

Thanks

Answer 1

I was able to solve this in the following manner. Any suggestions to make this better are most welcome.

>>> from lxml import etree
>>> SOAPENV_NAMESPACE = "http://schemas.xmlsoap.org/soap/envelope"
>>> SOAPENV = "{%s}" % SOAPENV_NAMESPACE
>>> ns0_NAMESPACE = "http://xmlns.CLT.com/consume/ENTBUS"
>>> ns0 = "{%s}" % ns0_NAMESPACE
>>> ns1_NAMESPACE = "http://xmlns.CLT.com/Core/ENTBUS"
>>> ns1 = "{%s}" % ns1_NAMESPACE
>>> ns2_NAMESPACE = "http://xmlns.CLT.com/output/EBO"
>>> ns2 = "{%s}" % ns2_NAMESPACE
>>> NSMAP = {'SoapEnv' : SOAPENV_NAMESPACE,'ns0':ns0_NAMESPACE,'ns1':ns1_NAMESPACE,'ns2':ns2_NAMESPACE}
>>> envelope = etree.Element(SOAPENV + "Envelope", nsmap=NSMAP)
>>> ConsumptionRequestENTBUS=etree.SubElement(envelope, ns0 + "ConsumptionRequestENTBUS", nsmap=NSMAP)
>>> ENTBUS=etree.SubElement(ConsumptionRequestENTBUS, ns1 + "ENTBUS", nsmap=NSMAP)
>>> ENTBUSHeader=etree.SubElement(ENTBUS, ns1 + "ENTBUSHeader", nsmap=NSMAP)
>>> ENTBUSDetail=etree.SubElement(ENTBUSHeader, ns2 + "ENTBUSDetail", nsmap=NSMAP)
>>> print(etree.tostring(envelope, pretty_print=True))
<SoapEnv:Envelope xmlns:ns0="http://xmlns.CLT.com/consume/ENTBUS" xmlns:ns1="http://xmlns.CLT.com/Core/ENTBUS" xmlns:ns2="h
ttp://xmlns.CLT.com/output/EBO" xmlns:SoapEnv="http://schemas.xmlsoap.org/soap/envelope">
  <ns0:ConsumptionRequestENTBUS>
    <ns1:ENTBUS>
      <ns1:ENTBUSHeader>
        <ns2:ENTBUSDetail/>
      </ns1:ENTBUSHeader>
    </ns1:ENTBUS>
  </ns0:ConsumptionRequestENTBUS>
</SoapEnv:Envelope>

Answer 2

The lxml tutorial does have a section on namespaces . However, if you're actually communicating with a SOAP webservice, I'd recommend using a proper library like suds or soapbox if possible.

Answer 3

Not sure if it's better but an alternative way to do it would be:

from lxml import etree
from lxml.builder import ElementMaker


nslist = {
        'soapenv':'http://schemas.xmlsoap.org/soap/envelope/',
        'ns0':'http://xmlns.CLT.com/consume/ENTBUS',
        'ns1':'http://xmlns.CLT.com/Core/ENTBUS',
        'ns2':'http://xmlns.CLT.com/output/EBO', 
        None: 'http://schemas.xmlsoap.org/soap/envelope/'}
 
E = ElementMaker(namespace="http://schemas.xmlsoap.org/soap/envelope/", nsmap=nslist)
E0 = ElementMaker(namespace="http://xmlns.CLT.com/consume/ENTBUS", nsmap={'ns0':'http://xmlns.CLT.com/consume/ENTBUS'})
E1 = ElementMaker(namespace="http://xmlns.CLT.com/Core/ENTBUS", nsmap={'ns0':'http://xmlns.CLT.com/Core/ENTBUS'})
E2 = ElementMaker(namespace="http://xmlns.CLT.com/output/EBO", nsmap={'ns2':'http://xmlns.CLT.com/output/EBO'})

out = E.Envelope(
    E.Header(), 
    E.Body(
        E0.ConsumptionRequestENTBUS(
            E1.ENTBUSHeader(
                E1.ENTBUSID('1')
            ),
            E0.Zone(
                E2.Consumption(
                    E2.BusCode('1')
                )
            )
        )
    )
)

print(etree.tostring(out, encoding="UTF-8", standalone="yes", pretty_print=True))