Common Patterns

Common Patterns

Pattern 1: Service Layer with Repository

Python

class UserService:
    def __init__(self, user_repo: UserRepository):
        self.user_repo = user_repo

    async def register_user(self, username: str, email: str) -> User:
        # Check if user exists
        existing = await self.user_repo.collection.find_one({"email": email})
        if existing:
            raise ValueError("Email already exists")

        # Create user
        user = User(username=username, email=email)
        return await self.user_repo.create(user)

Pattern 2: Aggregation Pipeline

Python

async def get_user_stats(self, user_id: str) -> dict:
    pipeline = [
        {"$match": {"author_id": user_id}},
        {"$group": {
            "_id": None,
            "total_posts": {"$sum": 1},
            "total_likes": {"$sum": "$likes"}
        }}
    ]
    result = await post_repo.collection.aggregate(pipeline).to_list(1)
    return result[0] if result else {"total_posts": 0, "total_likes": 0}

Pattern 3: Bulk Operations

Python

async def bulk_update_status(self, ids: List[str], status: str):
    from bson import ObjectId
    object_ids = [ObjectId(id) for id in ids]
    await self.collection.update_many(
        {"_id": {"$in": object_ids}},
        {"$set": {"status": status, "updated_at": datetime.utcnow()}}
    )

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