[Zope] Using PUT_factory for objects outside of ZODB

[John Barham]

I want to be able to intercept PUT requests to Zope to store objects
outside of the ZODB by storing the body of the PUT request in an SQL
database.  I've written a PUT_factory external method that calls the
function PUT_ParameterFile defined below:

==========

[...boilerplate Zope imports...]

class ParameterFile(Implicit):
    security = ClassSecurityInfo()
    security.declareObjectPublic()
    security.setDefaultAccess("allow")

    def __init__(self, context, job_batch_id, body):
        self.context = context
        self.job_batch_id = job_batch_id
        self.body = body

    def PUT(self, REQUEST, RESPONSE):
        self.context.SQL_UpdateJobBatchParameterFile(
                job_batch_id=self.job_batch_id, parameter_file=self.body)
        RESPONSE.setStatus(204)
        return RESPONSE

def PUT_ParameterFile(self, name, typ, body):
    if typ == "text/plain":
        return ParameterFile(self, name, body)

=============

The ParameterFile.PUT method is being called, but then Zope returns w/
the error "Can't pickle <extension class __builtin__.ParameterFile at
72918728>: attribute lookup __builtin__.ParameterFile failed".  Why is
Zope trying to pickle the ParameterFile object when it's handling PUT
itself?

TIA,

  John