generators: support custom ReferenceResolver class

[pahaz]

I need to override the logic of the ReferenceResolver class.

My customized ReferenceResolver looks like:

class StandardizedReferenceResolver(ReferenceResolver):
    def set(self, name, obj, scope=None):
        scope = self._check_scope(scope)
        assert obj is not None, "referenced objects cannot be None/null"
        self._objects[scope][name] = obj

    def setdefault(self, name, maker, scope=None):
        scope = self._check_scope(scope)
        ret = self.getdefault(name, None, scope)
        if ret is None:
            ret = maker()
            value = self.getdefault(name, None, scope)
            if value is None:
                self.set(name, ret, scope)
            elif value != ret and len(ret.properties) > len(value.properties):
                self.set(name, ret, scope)
            elif value != ret:
                logger.debug("during setdefault, maker for %s inserted a "
                             "value and returned a different value", name)
                ret = value
        return ret

    def with_scope(self, scope):
        assert scope in self.scopes, "unknown scope %s" % scope
        ret = StandardizedReferenceResolver(force_init=True)
        ret._objects = self._objects
        ret._force_scope = scope
        return ret

With that fix I can use:

from drf_yasg.generators import OpenAPISchemaGenerator

class StandardizedSchemaGenerator(OpenAPISchemaGenerator):
    reference_resolver_class = StandardizedReferenceResolver

[pahaz]

Is it going to be merged?

[axnsan12]

Yeah, seems okay.