feat!: Stricter non-null fields for relationships (#367)

to-many relationships are now non-null by default. (List[MyType] -> List[MyType!]!)
The behavior can be adjusted back to legacy using `converter.set_non_null_many_relationships(False)`
or using an `ORMField` manually setting the type for more granular Adjustments

graphene_sqlalchemy/converter.py

@@ -59,6 +59,39 @@
 
 is_selectin_available = getattr(strategies, "SelectInLoader", None)
 
+"""
+Flag for whether to generate stricter non-null fields for many-relationships.
+
+For many-relationships, both the list element and the list field itself will be
+non-null by default. This better matches ORM semantics, where there is always a
+list for a many relationship (even if it is empty), and it never contains None.
+
+This option can be set to False to revert to pre-3.0 behavior.
+
+For example, given a User model with many Comments:
+
+ class User(Base):
+ comments = relationship("Comment")
+
+The Schema will be:
+
+ type User {
+ comments: [Comment!]!
+ }
+
+When set to False, the pre-3.0 behavior gives:
+
+ type User {
+ comments: [Comment]
+ }
+"""
+use_non_null_many_relationships = True
+
+
+def set_non_null_many_relationships(non_null_flag):
+ global use_non_null_many_relationships
+ use_non_null_many_relationships = non_null_flag
+
 
 def get_column_doc(column):
  return getattr(column, "doc", None)
@@ -160,7 +193,14 @@ def _convert_o2m_or_m2m_relationship(
  )
 
  if not child_type._meta.connection:
- return graphene.Field(graphene.List(child_type), **field_kwargs)
+ # check if we need to use non-null fields
+ list_type = (
+ graphene.NonNull(graphene.List(graphene.NonNull(child_type)))
+ if use_non_null_many_relationships
+ else graphene.List(child_type)
+ )
+
+ return graphene.Field(list_type, **field_kwargs)
 
  # TODO Allow override of connection_field_factory and resolver via ORMField
  if connection_field_factory is None:

graphene_sqlalchemy/tests/test_converter.py

@@ -21,6 +21,7 @@
  convert_sqlalchemy_hybrid_method,
  convert_sqlalchemy_relationship,
  convert_sqlalchemy_type,
+ set_non_null_many_relationships,
 )
 from ..fields import UnsortedSQLAlchemyConnectionField, default_connection_field_factory
 from ..registry import Registry, get_global_registry
@@ -71,6 +72,16 @@ class Model(declarative_base()):
  )
 
 
+@pytest.fixture
+def use_legacy_many_relationships():
+ set_non_null_many_relationships(False)
+ try:
+ yield
+ finally:
+ set_non_null_many_relationships(True)
+
+
+
 def test_hybrid_prop_int():
  @hybrid_property
  def prop_method() -> int:
@@ -501,6 +512,30 @@ class Meta:
  True,
  "orm_field_name",
  )
+ # field should be [A!]!
+ assert isinstance(dynamic_field, graphene.Dynamic)
+ graphene_type = dynamic_field.get_type()
+ assert isinstance(graphene_type, graphene.Field)
+ assert isinstance(graphene_type.type, graphene.NonNull)
+ assert isinstance(graphene_type.type.of_type, graphene.List)
+ assert isinstance(graphene_type.type.of_type.of_type, graphene.NonNull)
+ assert graphene_type.type.of_type.of_type.of_type == A
+
+
+@pytest.mark.usefixtures("use_legacy_many_relationships")
+def test_should_manytomany_convert_connectionorlist_list_legacy():
+ class A(SQLAlchemyObjectType):
+ class Meta:
+ model = Pet
+
+ dynamic_field = convert_sqlalchemy_relationship(
+ Reporter.pets.property,
+ A,
+ default_connection_field_factory,
+ True,
+ "orm_field_name",
+ )
+ # field should be [A]
  assert isinstance(dynamic_field, graphene.Dynamic)
  graphene_type = dynamic_field.get_type()
  assert isinstance(graphene_type, graphene.Field)

graphene_sqlalchemy/tests/test_types.py

@@ -331,8 +331,10 @@ class Meta:
 
  pets_field = ReporterType._meta.fields["pets"]
  assert isinstance(pets_field, Dynamic)
- assert isinstance(pets_field.type().type, List)
- assert pets_field.type().type.of_type == PetType
+ assert isinstance(pets_field.type().type, NonNull)
+ assert isinstance(pets_field.type().type.of_type, List)
+ assert isinstance(pets_field.type().type.of_type.of_type, NonNull)
+ assert pets_field.type().type.of_type.of_type.of_type == PetType
  assert pets_field.type().description == "Overridden"