def valuefrompostdata(self, postdata):
        """This parameter method searches the POST data and retrieves the values it needs. It does not set the value yet though, but simply returns it. Needs to be explicitly passed to parameter.set()"""
        if self.multi: #multi parameters can be passed as  parameterid=choiceid1,choiceid2 or by setting parameterid[choiceid]=1 (or whatever other non-zero value)
            found = False
            if self.id in postdata:
                found = True
                passedvalues = postdata[self.id].split(',')
                values = []
                for choicekey in [x[0] for x in self.choices]:
                    if choicekey in passedvalues:
                        found = True
                        values.append(choicekey)
            else:
                values = []
                for choicekey in [x[0] for x in self.choices]:
                    if self.id+'['+choicekey+']' in postdata:
                        found = True
                        if postdata[self.id+'['+choicekey+']']:
                            values.append(choicekey)
            if not found:
                return None
            else:
                return values
        else:
            if self.id in postdata:
                return postdata[self.id]
            else:
                return None
This parameter method searches the POST data and retrieves the values it needs. It does not set the value yet though, but simply returns it. Needs to be explicitly passed to parameter.set()