[Soap-Python] rpclib -> spyne: multiple MethodDescriptor to a single proxy function

[C Anthony Risinger]

hello,

while briefly trying to update to the spyne codebase, i am encountering 
an AssertionError due to spyne enforcing a 1-to-1 mapping between 
MethodDescriptor and the function it wraps:

   File "/path/to/spyne/interface/_base.py", line 224, in populate_interface
     assert not s.get_method_id(method) in self.method_id_map
AssertionError

... the problem is that i am currently building the MethodDescriptors 
dynamically, and mapping to a single _proxy function; this SOAP service 
is really proxying/exposing another JSON service (no JSON support in 
rpclib/spyne during development).

service definition (disregard custom json functions, unrelated):

-----------------------------------------------
from rpclib import MethodDescriptor
from rpclib.interface.wsdl import Wsdl11
from rpclib.service import ServiceBase
from requests import request
import json

from awesome import models


API_VERISION_JSON = 1
API_VERISION_SOAP = 1


METHODS = [('method_one', 'put', 'some method two'),
            ('method_two', 'post', 'some method two')]


def _bind(udp):
     m, verb, doc = udp
     def f(*args, **kwds):
         name = kwds['_default_function_name']
         in_message = getattr(models, m)
         out_message = getattr(models, m+'Response', None)
         if out_message is None:
             out_message = getattr(models, m+'_response')
         desc = MethodDescriptor(function=_proxy,
                                 in_message=in_message,
                                 out_message=out_message,
                                 doc=doc,
                                 is_callback=False,
                                 is_async=False,
                                 mtom=False,
                                 in_header=None,
                                 out_header=None,
                                 faults=None,
                                 port_type=None,
                                 no_ctx=False,
                                 udp=udp,
                                 class_key=name)
         return desc
     f.__doc__ = doc
     f._is_rpc = True
     return f


def _proxy(ctx, req):
     res = None
     ret = None
     method, verb, doc = ctx.descriptor.udp
     host = 'http://%(SERVER_NAME)s:%(SERVER_PORT)s' % \
         ctx.transport.req_env
     endpoint = '%s/api/v%s/%s/' % (host, API_VERISION_JSON, method)
     headers = {'content-type': 'application/json'}
     try:
         res = request(verb, endpoint, headers=headers,
                       data=json.dumps(req.json(req)))
         res_json = json.loads(res.text)
     except Exception, e:
         import traceback
         if res:
             print res.text
         traceback.print_exc()
         raise e
     out_message = ctx.descriptor.out_message
     if len(out_message._type_info) == 1:
         out_message = out_message._type_info[0]
     return out_message.json(res_json)


MyService = type('MyService', (ServiceBase,),
     dict([(udp[0], _bind(udp)) for udp in METHODS]))
-----------------------------------------------

... thats's the complete -- working -- service definition, with only the 
method list truncated and some names changed to protect the innocent. in 
short: i store the method name, HTTP verb, and __doc__ in udp, then use 
that and the transport context to rebuild the real request.

i haven't spent much time investigating, but why is this restriction 
necessary?  the solution ATM means needlessly wrapping _proxy for each 
method with a module level function, since lambdas probably wouldn't 
work either (albeit, i didn't try :-)

how can i solve this cleanly, or better, patch spyne to not care what 
callable actually implements the method (since the pattern was working 
rather nicely)?

thanks!

-- 

C Anthony


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