fix for #226

docs/releases.md

@@ -1,3 +1,13 @@
+# 0.10.11
+
+## ✨ Features
+
+* 
+
+## 🐛 Fixes
+
+* Fix creation of auto through model for m2m relation with ForwardRef [#226](https://github.com/collerek/ormar/issues/226)
+
 # 0.10.10
 
 ## ✨ Features

ormar/models/helpers/sqlalchemy.py

@@ -2,6 +2,7 @@ import logging
 from typing import Dict, List, Optional, TYPE_CHECKING, Tuple, Type, Union
 
 import sqlalchemy
+from pydantic.typing import ForwardRef
 
 import ormar  # noqa: I100, I202
 from ormar.models.descriptors import RelationDescriptor
@@ -203,7 +204,7 @@ def _is_through_model_not_set(field: "BaseField") -> bool:
     :return: result of the check
     :rtype: bool
     """
-    return field.is_multi and not field.through
+    return field.is_multi and not field.through and not field.to.__class__ == ForwardRef
 
 
 def _is_db_field(field: "BaseField") -> bool:

ormar/models/newbasemodel.py

@@ -447,6 +447,9 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
                 field = cast(ForeignKeyField, field)
                 field.evaluate_forward_ref(globalns=globalns, localns=localns)
                 field.set_self_reference_flag()
+                if field.is_multi and not field.through:
+                    field = cast(ormar.ManyToManyField, field)
+                    field.create_default_through_model()
                 expand_reverse_relationship(model_field=field)
                 register_relation_in_alias_manager(field=field)
                 update_column_definition(model=cls, field=field)

tests/test_deferred/test_forward_cross_refs.py

@@ -1,4 +1,5 @@
 # type: ignore
+from typing import List, Optional
 
 import databases
 import pytest
@@ -17,10 +18,14 @@ engine = create_engine(DATABASE_URL)
 TeacherRef = ForwardRef("Teacher")
 
 
+class BaseMeta(ormar.ModelMeta):
+    metadata = metadata
+    database = db
+
+
 class Student(ormar.Model):
-    class Meta(ModelMeta):
-        metadata = metadata
-        database = db
+    class Meta(BaseMeta):
+        pass
 
     id: int = ormar.Integer(primary_key=True)
     name: str = ormar.String(max_length=100)
@@ -30,10 +35,8 @@ class Student(ormar.Model):
 
 
 class StudentTeacher(ormar.Model):
-    class Meta(ModelMeta):
+    class Meta(BaseMeta):
         tablename = "students_x_teachers"
-        metadata = metadata
-        database = db
 
 
 class Teacher(ormar.Model):
@@ -50,6 +53,35 @@ class Teacher(ormar.Model):
 
 Student.update_forward_refs()
 
+CityRef = ForwardRef("City")
+CountryRef = ForwardRef("Country")
+
+
+class Country(ormar.Model):
+    class Meta(BaseMeta):
+        tablename = "countries"
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=128)
+    capital: Optional[CityRef] = ormar.ForeignKey(
+        CityRef, related_name="capital_city", nullable=True
+    )
+    borders: Optional[List[CountryRef]] = ormar.ManyToMany(CountryRef)
+
+
+class City(ormar.Model):
+    class Meta(BaseMeta):
+        tablename = "cities"
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=128)
+    country: Country = ormar.ForeignKey(
+        Country, related_name="cities", skip_reverse=True
+    )
+
+
+Country.update_forward_refs()
+
 
 @pytest.fixture(autouse=True, scope="module")
 def create_test_database():
@@ -114,3 +146,23 @@ async def test_double_relations():
             assert len(quibble.own_students) == 2
             assert quibble.own_students[1].name == "John"
             assert quibble.own_students[0].name == "Anna"
+
+
+@pytest.mark.asyncio
+async def test_auto_through_model():
+    async with db:
+        async with db.transaction(force_rollback=True):
+            england = await Country(name="England").save()
+            france = await Country(name="France").save()
+            london = await City(name="London", country=england).save()
+            england.capital = london
+            await england.update()
+            await england.borders.add(france)
+
+            check = await Country.objects.select_related(["capital", "borders"]).get(
+                name="England"
+            )
+            assert check.name == "England"
+            assert check.capital.name == "London"
+            assert check.capital.country.pk == check.pk
+            assert check.borders[0] == france