working basic many to many relationships

tests/test_foreign_keys.py

@@ -1,5 +1,3 @@
-import gc
-
 import databases
 import pytest
 import sqlalchemy
@@ -179,7 +177,7 @@ async def test_model_removal_from_relations():
         await track3.save()
 
         assert len(album.tracks) == 3
-        album.tracks.remove(track1)
+        await album.tracks.remove(track1)
         assert len(album.tracks) == 2
         assert track1.album is None
 
@@ -187,7 +185,7 @@ async def test_model_removal_from_relations():
         track1 = await Track.objects.get(title="The Birdman")
         assert track1.album is None
 
-        album.tracks.add(track1)
+        await album.tracks.add(track1)
         assert len(album.tracks) == 3
         assert track1.album == album
 

tests/test_many_to_many.py

@@ -0,0 +1,178 @@
+import databases
+import pytest
+import sqlalchemy
+
+import ormar
+from ormar.exceptions import RelationshipInstanceError
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL, force_rollback=True)
+metadata = sqlalchemy.MetaData()
+
+
+class Author(ormar.Model):
+    class Meta:
+        tablename = "authors"
+        database = database
+        metadata = metadata
+
+    id: ormar.Integer(primary_key=True)
+    first_name: ormar.String(max_length=80)
+    last_name: ormar.String(max_length=80)
+
+
+class Category(ormar.Model):
+    class Meta:
+        tablename = "categories"
+        database = database
+        metadata = metadata
+
+    id: ormar.Integer(primary_key=True)
+    name: ormar.String(max_length=40)
+
+
+class PostCategory(ormar.Model):
+    class Meta:
+        tablename = "posts_categories"
+        database = database
+        metadata = metadata
+
+
+class Post(ormar.Model):
+    class Meta:
+        tablename = "posts"
+        database = database
+        metadata = metadata
+
+    id: ormar.Integer(primary_key=True)
+    title: ormar.String(max_length=200)
+    categories: ormar.ManyToMany(Category, through=PostCategory)
+    author: ormar.ForeignKey(Author)
+
+
+@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)
+
+
+@pytest.fixture(scope="function")
+async def cleanup():
+    yield
+    await PostCategory.objects.delete()
+    await Post.objects.delete()
+    await Category.objects.delete()
+    await Author.objects.delete()
+
+
+@pytest.mark.asyncio
+async def test_assigning_related_objects(cleanup):
+    guido = await Author.objects.create(first_name="Guido", last_name="Van Rossum")
+    post = await Post.objects.create(title="Hello, M2M", author=guido)
+    news = await Category.objects.create(name="News")
+
+    # Add a category to a post.
+    await post.categories.add(news)
+    # or from the other end:
+    await news.posts.add(post)
+
+    # Creating related object from instance:
+    await post.categories.create(name="Tips")
+    assert len(post.categories) == 2
+
+    post_categories = await post.categories.all()
+    assert len(post_categories) == 2
+
+
+@pytest.mark.asyncio
+async def test_quering_of_the_m2m_models(cleanup):
+    # orm can do this already.
+    guido = await Author.objects.create(first_name="Guido", last_name="Van Rossum")
+    post = await Post.objects.create(title="Hello, M2M", author=guido)
+    news = await Category.objects.create(name="News")
+    # tl;dr: `post.categories` exposes the QuerySet API.
+
+    await post.categories.add(news)
+
+    post_categories = await post.categories.all()
+    assert len(post_categories) == 1
+
+    assert news == await post.categories.get(name="News")
+
+    num_posts = await news.posts.count()
+    assert num_posts == 1
+
+    posts_about_m2m = await news.posts.filter(title__contains="M2M").all()
+    assert len(posts_about_m2m) == 1
+    assert posts_about_m2m[0] == post
+    posts_about_python = await Post.objects.filter(categories__name="python").all()
+    assert len(posts_about_python) == 0
+
+    # Traversal of relationships: which categories has Guido contributed to?
+    category = await Category.objects.filter(posts__author=guido).get()
+    assert category == news
+    # or:
+    category2 = await Category.objects.filter(posts__author__first_name="Guido").get()
+    assert category2 == news
+
+
+@pytest.mark.asyncio
+async def test_removal_of_the_relations(cleanup):
+    guido = await Author.objects.create(first_name="Guido", last_name="Van Rossum")
+    post = await Post.objects.create(title="Hello, M2M", author=guido)
+    news = await Category.objects.create(name="News")
+    await post.categories.add(news)
+    assert len(await post.categories.all()) == 1
+    await post.categories.remove(news)
+    assert len(await post.categories.all()) == 0
+    # or:
+    await news.posts.add(post)
+    assert len(await news.posts.all()) == 1
+    await news.posts.remove(post)
+    assert len(await news.posts.all()) == 0
+
+    # Remove all related objects:
+    await post.categories.add(news)
+    await post.categories.clear()
+    assert len(await post.categories.all()) == 0
+
+    # post would also lose 'news' category when running:
+    await post.categories.add(news)
+    await news.delete()
+    assert len(await post.categories.all()) == 0
+
+
+@pytest.mark.asyncio
+async def test_selecting_related(cleanup):
+    guido = await Author.objects.create(first_name="Guido", last_name="Van Rossum")
+    post = await Post.objects.create(title="Hello, M2M", author=guido)
+    news = await Category.objects.create(name="News")
+    recent = await Category.objects.create(name="Recent")
+    await post.categories.add(news)
+    await post.categories.add(recent)
+    assert len(await post.categories.all()) == 2
+    # Loads categories and posts (2 queries) and perform the join in Python.
+    categories = await Category.objects.select_related("posts").all()
+    # No extra queries needed => no more `await`s required.
+    for category in categories:
+        assert category.posts[0] == post
+
+    news_posts = await news.posts.select_related("author").all()
+    assert news_posts[0].author == guido
+
+    assert (await post.categories.limit(1).all())[0] == news
+    assert (await post.categories.offset(1).limit(1).all())[0] == recent
+
+    assert await post.categories.first() == news
+
+    assert await post.categories.exists()
+
+
+@pytest.mark.asyncio
+async def test_selecting_related_fail_without_saving(cleanup):
+    guido = await Author.objects.create(first_name="Guido", last_name="Van Rossum")
+    post = Post(title="Hello, M2M", author=guido)
+    with pytest.raises(RelationshipInstanceError):
+        await post.categories.all()