Issue with nested self-referencing schemas

[mouadennasri]

I have an issue with nested self-referencing schema,

class GroupSchema(HasPermissionMixin, ModelSchema):
    content = fields.Nested(GroupParamSchema, required=True)

class GroupParamSchema(Schema):
    filters = fields.Nested(FilterSchema, required=True, many=True)

class FilterSchema(Schema):
    next_filter = fields.Nested("FilterSchema", required=False, allow_none=True)

The issue is with FilterSchema

I have a helper method that converts Marshmallow Schema to an OpenApiJson object:

def get_openapi_schema(
    serializer,
):
    spec = APISpec(
        title="",
        version="",
        openapi_version="3.0.2",
        plugins=[MarshmallowPlugin(schema_name_resolver=schema_name_resolver)],
    )

    openapi_schema = OpenAPIConverter(openapi_version="3.0.2",schema_name_resolver=schema_name_resolver,spec=spec)
    return {200: openapi_schema.schema2jsonschema(serializer)}

The schema_name_resolver as described in the docs should not return None for Circular schemas

def schema_name_resolver(schema):

    schema_name = resolve_schema_cls(schema).__name__
    circular = False
    values = list(schema.fields.values())

    for value in values:
        if value.__class__.__name__ == "Nested":
            if value.nested == schema_name:
                circular = True
                break

    if circular:
        return schema_name

    return None

But it still complains:

 File "/usr/local/lib/python3.9/site-packages/apispec/ext/marshmallow/openapi.py", line 297, in get_ref_dict
    ref_schema = self.spec.components.get_ref("schema", self.refs[schema_key])
KeyError: (<class 'veylinx.api.insights.serializers.base.FilterSchema'>, None, frozenset(), frozenset(), frozenset(), False)

And I'm sure that the schema_name_resolver is returning a string when the schema is circular

Using a resolver as lambda schema_class: None will raise the error below which is understandable!

apispec.exceptions.APISpecError: Name resolver returned None for schema <FilterSchema(many=False)> which is part of a chain of circular referencing schemas. Please ensure that the schema_name_resolver passed to MarshmallowPlugin returns a string for all circular referencing schemas.

I'm using:

Django==4.0.8
apispec==6.0.2
marshmallow==3.19.0
Debian GNU/Linux 11 (bullseye)

[lafrech]

From a very quick look, I have the feeling you're comparing a schema class/instance and a name. Should it be something more like this?

if resolve_schema_cls(value.nested).__name__ == schema_name:

or perhaps even

if resolve_schema_cls(value.nested) == resolve_schema_cls(schema):

[mouadennasri]

@lafrech thank you for the quick feedback! but sadly that didn't solve the issue, the ApiSpec.refs is empty and it raises:

    ref_schema = self.spec.components.get_ref("schema", self.refs[schema_key])
KeyError: (<class 'api.insights.serializers.base.FilterSchema'>, None, frozenset(), frozenset(), frozenset(), False)

These are some debug outputs:

(Pdb) self.refs
{}
(Pdb) schema_key
(<class 'api.insights.serializers.base.FilterSchema'>, None, frozenset(), frozenset(), frozenset(), False)
(Pdb) self.spec.components.to_dict()
{
    "schemas": {
        "FilterSchema": {
            "type": "object",
            "properties": {
                "next_filter": {
                    "nullable": True,
                    "allOf": [{"$ref": "#/components/schemas/FilterSchema"}],
                },
                "filter_type": {
                    "type": "string",
                    "enum": [
                        "Filter",
                        "IsFinishedFilter",
                    ],
                },
                "params": {
                    "type": "array",
                    "nullable": True,
                    "items": {"nullable": True},
                },
                "operator_class": {
                    "type": "string",
                    "enum": [
                        "QueryOp",
                        "AndOperator",
                    ],
                },
                "legacy_filter": {"type": "object"},
                "auction_id": {
                    "type": "array",
                    "nullable": True,
                    "items": {"type": "string"},
                },
                "filter_join": {
                    "type": "string",
                    "enum": [
                        "QueryOp",
                        "AndOperator"
                    ],
                },
            },
            "required": ["filter_type", "operator_class"],
        }
    }
}
(Pdb) self.spec.components.get_ref("schema", "FilterSchema")
{'$ref': '#/components/schemas/FilterSchema'}