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ManyToMany

A ManyToMany field creates a many-to-many relationship via a join table.

Defining ManyToMany​

class Post(Model):
    title = CharField(max_length=200)

class Tag(Model):
    name  = CharField(max_length=50)
    posts = ManyToManyField(Post)

Ryx automatically creates a join table tag_posts with columns tag_id and post_id.

Custom Join Table​

Specify your own through model for extra fields:

class Post(Model):
    title = CharField(max_length=200)

class Tag(Model):
    name  = CharField(max_length=50)
    posts = ManyToManyField(Post, through="PostTag")

class PostTag(Model):
    post     = ForeignKey(Post, on_delete="CASCADE")
    tag      = ForeignKey(Tag, on_delete="CASCADE")
    added_at = DateTimeField(auto_now_add=True)

    class Meta:
        unique_together = [("post_id", "tag_id")]

Managing Relations​

# Get the manager
tag = await Tag.objects.get(pk=1)
manager = tag.posts  # ManyToManyManager

# All related posts
posts = await tag.posts.all()

# Add a relation
await tag.posts.add(post_id=5)

# Remove a relation
await tag.posts.remove(post_id=5)

# Replace all relations
await tag.posts.set([1, 2, 3])

# Clear all relations
await tag.posts.clear()

# Count
count = await tag.posts.count()

# Check existence
exists = await tag.posts.filter(active=True).exists()

Querying Through M2M​

# Posts with a specific tag
Post.objects.filter(tags__name="python")

# Tags for a specific post
Tag.objects.filter(posts__id=5)

# Posts with ANY of these tags
Post.objects.filter(tags__name__in=["python", "rust"])

Next Steps​

→ select_related — Eager loading with JOINs