graphql-python / graphql-python/graphene-sqlalchemy

hybrid_property annotations with built-in types defaulting to `ForwardRef` and failing schema compilation

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描述

dependencies:
```
python 3.10.7

sqlalchemy==1.4.48
graphene==3.2.2
graphene-sqlalchemy==v3.0.0b4
graphql-server[flask]==v3.0.0b6
```

I am upgrading from `graphene==2.1.9` and `graphene-sqlalchemy==2.3.0` where these hybrid properties worked.

simplified example:
```python

# myproject/routes/graphql_view.py

from myproject.schema import schema

GraphQLView.as_view('graphql', schema=schema, graphiql=False) # simplified, used in flask create_app in __init__.py

# myproject/models/core.py

class MyModel(db.Model, DictMixin, Timestamp):
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
...

@hybrid_property
def prop_string -> str:
# logic based on model's other fields
result: str = ...
return result

@hybrid_property
def prop_boolean -> bool:
# logic based on model's other fields
result: bool = ...
return result

# myproject/schema.py

from myproject.models.core import MyModel

class MyModelQuery(SQLAlchemyObjectType):
class Meta:
model = MyModel
interfaces = (relay.Node,)

class Query(graphene.ObjectType):
node = relay.Node.Field()
... # other query fields
model = graphene.Field(MyModelQuery, model_id=graphene.Int())

def resolve_model(self, info, model_id):
query = MyModelQuery.get_query(info)
return query.get(model_id)

schema = graphene.Schema(query=Query, mutation=Mutation)
```

It seems like support was added for these annotations in https://github.com/graphql-python/graphene-sqlalchemy/pull/340 in v3.0.0b2, but then is no longer working as expected since several refactors.

I get this error for the string return type hybrid

```
../../../myproject/schema.py:581: in
schema = graphene.Schema(query=Query, mutation=Mutation)
../../../venv/lib/python3.10/site-packages/graphene/types/schema.py:440: in __init__
self.graphql_schema = GraphQLSchema(
../../../venv/lib/python3.10/site-packages/graphql/type/schema.py:224: in __init__
collect_referenced_types(query)
../../../venv/lib/python3.10/site-packages/graphql/type/schema.py:433: in collect_referenced_types
collect_referenced_types(field.type)
../../../venv/lib/python3.10/site-packages/graphql/type/schema.py:433: in collect_referenced_types
collect_referenced_types(field.type)
../../../venv/lib/python3.10/site-packages/graphql/type/schema.py:433: in collect_referenced_types
collect_referenced_types(field.type)
../../../venv/lib/python3.10/site-packages/graphql/type/schema.py:432: in collect_referenced_types
for field in named_type.fields.values():
/[...]/.pyenv/versions/3.10.7/lib/python3.10/functools.py:981: in __get__
val = self.func(instance)
../../../venv/lib/python3.10/site-packages/graphql/type/definition.py:811: in fields
raise cls(f"{self.name} fields cannot be resolved. {error}") from error
E TypeError: MyModelQuery fields cannot be resolved. No model found in Registry for forward reference for type ForwardRef('str'). Only forward references to other SQLAlchemy Models mapped to SQLAlchemyObjectTypes are allowed.
```

and this for the Boolean.

```
TypeError: MyModelQuery fields cannot be resolved. No model found in Registry for forward reference for type ForwardRef('bool'). Only forward references to other SQLAlchemy Models mapped to SQLAlchemyObjectTypes are allowed.
```

`MyModel` in reality has many many fields so it was also hard to figure out it was the hybrid_property fields that were causing problems, vs. the actual relationship fields etc

Which seems to be because the function `convert_hybrid_property_return_type`
https://github.com/graphql-python/graphene-sqlalchemy/blob/v3.0.0b4/graphene_sqlalchemy/converter.py#L640

returns a string version of the type, and string defaults to being processed by `convert_sqlalchemy_hybrid_property_bare_str` even though those strings are valid types, not `ForwardRef`s.
https://github.com/graphql-python/graphene-sqlalchemy/blob/v3.0.0b4/graphene_sqlalchemy/converter.py#L632

I am getting around this by explicitly declaring the graphene types but my understanding was that graphene-sqlalchemy should be able to pick them up automatically due to the recent support that was integrated, as referenced above.

workaround:
```python
class MyModelQuery(SQLAlchemyObjectType):
class Meta:
model = MyModel
interfaces = (relay.Node,)

prop_string = graphene.String()
prop_boolean = graphene.Boolean()
```

If this is intended behaviour, could the error be more helpful? Spent several hours digging as I was not attempting anything with a ForwardRef type.

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研究方向

Inspect graphene_sqlalchemy/converter.py, especially convert_hybrid_property_return_type and convert_sqlalchemy_hybrid_property_bare_str, using the reported MyModel hybrid_property examples as the reproduction. Verify how annotated str and bool return types are converted during schema construction. Done means built-in annotations no longer fail schema compilation as ForwardRef values, or the resulting error clearly explains the supported behavior.

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評估

技術堆疊
python, sqlalchemy
領域
api, database
Issue 類型
缺陷
難度
3/5
預估耗時
1-2 天
活躍度
停滯
描述清晰度
描述清楚
新手友好度
35/100

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