Pythonmongo_patterns.py
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from pymongo import MongoClient, ASCENDING, DESCENDING
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from pymongo.errors import DuplicateKeyError
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from datetime import datetime, timedelta
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import random
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client = MongoClient("mongodb://localhost:27017/")
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db = client["learn_db"]
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orders = db["orders"]
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# Drop and recreate for clean demo
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orders.drop()
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# Insert sample data
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categories = ["Electronics", "Clothing", "Books"]
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docs = [
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    {
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        "orderId": f"ORD-{i:04d}",
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        "customerId": f"CUST-{random.randint(1, 5)}",
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        "category": random.choice(categories),
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        "amount": round(random.uniform(10, 500), 2),
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        "createdAt": datetime.utcnow() - timedelta(days=random.randint(0, 30)),
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        "status": random.choice(["pending", "shipped", "delivered"]),
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    }
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    for i in range(1, 21)
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]
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result = orders.insert_many(docs)
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print(f"Inserted {len(result.inserted_ids)} orders")
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# Query with operators
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high_value = list(orders.find(
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    {"amount": {"$gt": 200}, "status": {"$in": ["shipped", "delivered"]}},
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    {"orderId": 1, "amount": 1, "status": 1, "_id": 0},  # projection
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))
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print(f"High-value delivered/shipped orders: {len(high_value)}")
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# Update
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update_result = orders.update_many(
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    {"status": "pending", "amount": {"$lt": 50}},
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    {"$set": {"status": "cancelled"}, "$currentDate": {"updatedAt": True}},
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)
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print(f"Cancelled {update_result.modified_count} small pending orders")
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# Aggregation pipeline
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pipeline = [
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    {"$match": {"status": {"$ne": "cancelled"}}},
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    {"$group": {
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        "_id": "$category",
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        "totalRevenue": {"$sum": "$amount"},
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        "orderCount": {"$sum": 1},
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        "avgOrder": {"$avg": "$amount"},
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    }},
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    {"$sort": {"totalRevenue": -1}},
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    {"$project": {
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        "category": "$_id",
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        "totalRevenue": {"$round": ["$totalRevenue", 2]},
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        "orderCount": 1,
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        "avgOrder": {"$round": ["$avgOrder", 2]},
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        "_id": 0,
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    }},
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]
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for row in orders.aggregate(pipeline):
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    print(row)
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# Index creation
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orders.create_index([("customerId", ASCENDING), ("createdAt", DESCENDING)], name="cust_date_idx")
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print("Index created")
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# Explain query plan
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explanation = orders.find({"customerId": "CUST-1"}).sort("createdAt", -1).explain()
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winning_plan = explanation["queryPlanner"]["winningPlan"]
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print(f"Winning plan stage: {winning_plan.get('stage')}")
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