Unintended namespace overwriting across independent models

[Visparu]

Hi there,

first off, thanks a ton for this module. It has drastically helped me keep my XML-related code in line with all my other Pydantic models.

I have come across an unusual and, from what I can tell, probably unintended behavior. When assigning multiple namespace maps with different names but the same ns-links and independently assigning them to different models, the last assigned namespace map overwrites all previously used ones. Instead of trying to explain it further, I'll just provide an example:

I created the following file:

from pydantic_xml import BaseXmlModel, element


_SOAP_NS: str = "https://www.w3.org/2003/05/soap-envelope"
_SAP_NS:  str = "urn:sap-com:document:sap:soap:functions:mc-style"

_REQUEST_NSMAP:  dict[str, str] = {"soap": _SOAP_NS, "urn": _SAP_NS}
_RESPONSE_NSMAP: dict[str, str] = {"env":  _SOAP_NS, "n0":  _SAP_NS}


class Test(BaseXmlModel):
    test1: int = element("Test1")
    test2: str = element("Test2")


##### Request models #####

class RequestBody(BaseXmlModel, ns = "urn", nsmap = _REQUEST_NSMAP, tag = "Body"):
    test: Test = element("Test", "urn")


class RequestEnvelope(BaseXmlModel, ns = "soap", nsmap = _REQUEST_NSMAP, tag = "Envelope"):
    body: RequestBody = element("Body", "soap")


##### Response models #####

class ResponseBody(BaseXmlModel, ns = "n0", nsmap = _RESPONSE_NSMAP, tag = "Body"):
    test: Test = element("Test", "n0")


class ResponseEnvelope(BaseXmlModel, ns = "env", nsmap = _RESPONSE_NSMAP, tag = "Envelope"):
    body: ResponseBody = element("Body", "env")


##### Execution #####

request_envelope: RequestEnvelope = RequestEnvelope(
    body=RequestBody(
        test=Test(
            test1=1,
            test2="abc"
        )
    )
)

response_envelope: ResponseEnvelope = ResponseEnvelope(
    body=ResponseBody(
        test=Test(
            test1=2,
            test2="def"
        )
    )
)

print("===============REQUEST================")
print(request_envelope.to_xml())
print("===============RESPONSE================")
print(response_envelope.to_xml())

As you can see, I create two sets of SOAP envelopes - RequestEnvelope and ResponseEnvelope. These envelopes should be namespaced differently, specifically:

• RequestEnvelope and RequestBody should be in namespace soap and Test1 should be in namespace urn
• ResponseEnvelope and ResponseBody should be in namespace env and Test1 should be in namespace n0

So the expected output would be:

RequestEnvelope

<soap:Envelope xmlns:soap="https://www.w3.org/2003/05/soap-envelope" xmlns:urn="urn:sap-com:document:sap:soap:functions:mc-style">
	<soap:Body>
		<urn:Test>
			<Test1>1</Test1>
			<Test2>abc</Test2>
		</urn:Test>
	</soap:Body>
</soap:Envelope>

ResponseEnvelope

<env:Envelope xmlns:env="https://www.w3.org/2003/05/soap-envelope" xmlns:n0="urn:sap-com:document:sap:soap:functions:mc-style">
	<env:Body>
		<n0:Test>
			<Test1>2</Test1>
			<Test2>def</Test2>
		</n0:Test>
	</env:Body>
</env:Envelope>

However, what actually happens is that the RequestEnvelope also uses env and n0:

RequestEnvelope

<env:Envelope xmlns:env="https://www.w3.org/2003/05/soap-envelope" xmlns:n0="urn:sap-com:document:sap:soap:functions:mc-style">
	<env:Body>
		<n0:Test>
			<Test1>1</Test1>
			<Test2>abc</Test2>
		</n0:Test>
	</env:Body>
</env:Envelope>

ResponseEnvelope

<env:Envelope xmlns:env="https://www.w3.org/2003/05/soap-envelope" xmlns:n0="urn:sap-com:document:sap:soap:functions:mc-style">
	<env:Body>
		<n0:Test>
			<Test1>2</Test1>
			<Test2>def</Test2>
		</n0:Test>
	</env:Body>
</env:Envelope>

This issue is very likely connected to the namespaces pointing to the same URLs. When given different URLs, the given example works just as intended. I have not found any workaround for this and it haunts me quite a bit since I do have use cases for which this scenario applies.

I would greatly appreciate any help here. I would already be very happy with any workaround for the time being.

[Visparu]

Quick addendum:

Even when separating the models completely by introducing a Test2 class for the ResponseBody, this behavior still occurs. So it doesn't seem to be an issue related to some parent/child namespace inheritance.

I don't know whether that was on the table at all but I thought to add this since I did just stumble over it.

[dapper91]

@Visparu Hi,

which version of pydantic-xml and lxml you use? On my side I get the following result:

===============REQUEST================
<soap:Envelope xmlns:soap="https://www.w3.org/2003/05/soap-envelope" xmlns:urn="urn:sap-com:document:sap:soap:functions:mc-style">
  <soap:Body>
    <urn:Test>
      <Test1>1</Test1>
      <Test2>abc</Test2>
    </urn:Test>
  </soap:Body>
</soap:Envelope>

===============RESPONSE================
<env:Envelope xmlns:env="https://www.w3.org/2003/05/soap-envelope" xmlns:n0="urn:sap-com:document:sap:soap:functions:mc-style">
  <env:Body>
    <n0:Test>
      <Test1>2</Test1>
      <Test2>def</Test2>
    </n0:Test>
  </env:Body>
</env:Envelope>