Introspecting a WSDL with Python Zeep

Question

I am attempting to use Zeep to describe the operations and types in a given WSDL, so that a program knows the operation names, their parameter names, the parameter types, and parameter attributes.

This info will be used to dynamically generate a UI for a given WSDL.

What I have got so far is just the string representations of the operations and types. Using code similar to what is found in this answer.

Here's an example:

from zeep import Client
import operator

wsdl = 'http://webservices.amazon.com/AWSECommerceService/AWSECommerceService.wsdl'
client = Client(wsdl)

# get each operation signature
for service in client.wsdl.services.values():
    print("service:", service.name)
    for port in service.ports.values():
        operations = sorted(
            port.binding._operations.values(),
            key=operator.attrgetter('name'))

        for operation in operations:
            print("method :", operation.name)
            print("  input :", operation.input.signature())
            print()
    print()

# get a specific type signature by name
complextype = client.get_type('ns0:CartGetRequest')
print(complextype.name)
print(complextype.signature())

This gives an output like the following (shortened for brevity)

[...]

method : CartCreate
  input : MarketplaceDomain: xsd:string, AWSAccessKeyId: xsd:string, AssociateTag: xsd:string, Validate: xsd:string, XMLEscaping: xsd:string, Shared: ns0:CartCreateRequest, Request: ns0:CartCreateRequest[]

method : CartGet
  input : MarketplaceDomain: xsd:string, AWSAccessKeyId: xsd:string, AssociateTag: xsd:string, Validate: xsd:string, XMLEscaping: xsd:string, Shared: ns0:CartGetRequest, Request: ns0:CartGetRequest[]

[...]


CartGetRequest
{http://webservices.amazon.com/AWSECommerceService/2011-08-01}CartGetRequest(CartId: xsd:string, HMAC: xsd:string, MergeCart: xsd:string, ResponseGroup: xsd:string[])

The string representations returned by .signature() have the names and types, but I don't know how to parse them out individually. I have tried looping over each objects attrs with dir() as well, and they don't contain this info. It seems to be nested much deeper.

I could parse the string representations themselves, but then I am also missing whether or not the parameter is optional (more specifically, if it has the attribute minOccurs=0

It seems like SOAPpy actually has this functionality, but isn't maintained anymore.

So is there a way to introspect a WSDL with zeep that provides granular information about each operation, it's parameter names, types, and attributes similar to the SOAPpy implementation? Or should I parse the signature, or alternatively, parse the WSDL with a regular XML parser.

Answer 1

You can access parameter elements with operation.input.body.type.elements, which is a list of tuples containing element objects. These objects contain information such as the type.

(Pdb) operation.input.body.type.elements
[('MarketplaceDomain', <Element(name='MarketplaceDomain', type=<zeep.xsd.types.builtins.String object at 0x7f1bd8a4b320>)>), ('AWSAccessKeyId', <Element(name='AWSAccessKeyId', type=<zeep.xsd.types.builtins.String object at 0x7f1bd8a4b320>)>), ('AssociateTag', <Element(name='AssociateTag', type=<zeep.xsd.types.builtins.String object at 0x7f1bd8a4b320>)>), ('Validate', <Element(name='Validate', type=<zeep.xsd.types.builtins.String object at 0x7f1bd8a4b320>)>), ('XMLEscaping', <Element(name='XMLEscaping', type=<zeep.xsd.types.builtins.String object at 0x7f1bd8a4b320>)>), ('Shared', <Element(name='Shared', type=<zeep.xsd.dynamic_types.BrowseNodeLookupRequest object at 0x7f1bd8177e48>)>), ('Request', <Element(name='Request', type=<zeep.xsd.dynamic_types.BrowseNodeLookupRequest object at 0x7f1bd8177e48>)>)]
(Pdb) operation.input.body.type.elements[0][1].name
'MarketplaceDomain'
(Pdb) operation.input.body.type.elements[0][1].type.name
'string'
(Pdb) operation.input.body.type.elements[0][1].is_optional
True

Answer 2

Based on the answer from jordanm, I used the following to get all of the data I needed on the available methods

from zeep import Client
from pprint import pprint

wsdl = 'http://webservices.amazon.com/AWSECommerceService/AWSECommerceService.wsdl'
client = Client(wsdl)


def parseElements(elements):
    all_elements = {}
    for name, element in elements:
        all_elements[name] = {}
        all_elements[name]['optional'] = element.is_optional
        if hasattr(element.type, 'elements'):
            all_elements[name]['type'] = parseElements(
                element.type.elements)
        else:
            all_elements[name]['type'] = str(element.type)

    return all_elements


interface = {}
for service in client.wsdl.services.values():
    interface[service.name] = {}
    for port in service.ports.values():
        interface[service.name][port.name] = {}
        operations = {}
        for operation in port.binding._operations.values():
            operations[operation.name] = {}
            operations[operation.name]['input'] = {}
            elements = operation.input.body.type.elements
            operations[operation.name]['input'] = parseElements(elements)
        interface[service.name][port.name]['operations'] = operations


pprint(interface)