allow customization of through model relation names

tests/test_relations/test_customizing_through_model_relation_names.py

@@ -0,0 +1,84 @@
+import databases
+import pytest
+import sqlalchemy
+
+import ormar
+from tests.settings import DATABASE_URL
+
+metadata = sqlalchemy.MetaData()
+database = databases.Database(DATABASE_URL, force_rollback=True)
+
+
+class Course(ormar.Model):
+    class Meta:
+        database = database
+        metadata = metadata
+
+    id: int = ormar.Integer(primary_key=True)
+    course_name: str = ormar.String(max_length=100)
+
+
+class Student(ormar.Model):
+    class Meta:
+        database = database
+        metadata = metadata
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+    courses = ormar.ManyToMany(
+        Course,
+        through_relation_name="student_id",
+        through_reverse_relation_name="course_id",
+    )
+
+
+# create db and tables
+@pytest.fixture(autouse=True, scope="module")
+def create_test_database():
+    engine = sqlalchemy.create_engine(DATABASE_URL)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)
+
+
+def test_tables_columns():
+    through_meta = Student.Meta.model_fields["courses"].through.Meta
+    assert "course_id" in through_meta.table.c
+    assert "student_id" in through_meta.table.c
+    assert "course_id" in through_meta.model_fields
+    assert "student_id" in through_meta.model_fields
+
+
+@pytest.mark.asyncio
+async def test_working_with_changed_through_names():
+    async with database:
+        async with database.transaction(force_rollback=True):
+            to_save = {
+                "course_name": "basic1",
+                "students": [{"name": "Jack"}, {"name": "Abi"}],
+            }
+            await Course(**to_save).save_related(follow=True, save_all=True)
+            course_check = await Course.objects.select_related("students").get()
+
+            assert course_check.course_name == "basic1"
+            assert course_check.students[0].name == "Jack"
+            assert course_check.students[1].name == "Abi"
+
+            students = await course_check.students.all()
+            assert len(students) == 2
+
+            student = await course_check.students.get(name="Jack")
+            assert student.name == "Jack"
+
+            students = await Student.objects.select_related("courses").all(
+                courses__course_name="basic1"
+            )
+            assert len(students) == 2
+
+            course_check = (
+                await Course.objects.select_related("students")
+                .order_by("students__name")
+                .get()
+            )
+            assert course_check.students[0].name == "Abi"
+            assert course_check.students[1].name == "Jack"