Agent skill

mongodb-aggregation-pipeline

Master MongoDB aggregation pipeline for complex data transformations. Learn pipeline stages, grouping, filtering, and data transformation. Use when analyzing data, creating reports, or transforming documents.

View SKILL.md on GitHub Repository
Stars 1
Forks 0

Install this agent skill to your Project

npx add-skill https://github.com/pluginagentmarketplace/custom-plugin-mongodb/tree/main/skills/mongodb-aggregation

SKILL.md

MongoDB Aggregation Pipeline

Master powerful data transformation with aggregation pipeline.

Quick Start

Basic Pipeline Structure

javascript
const result = await collection.aggregate([
  { $match: { status: 'active' } },
  { $group: { _id: '$category', count: { $sum: 1 } } },
  { $sort: { count: -1 } },
  { $limit: 10 }
]).toArray();

Common Pipeline Stages

javascript
// $match: Filter documents (like WHERE in SQL)
{ $match: { age: { $gte: 18 }, status: 'active' } }

// $group: Group documents and aggregate
{ $group: {
  _id: '$city',
  total: { $sum: '$amount' },
  average: { $avg: '$price' },
  count: { $sum: 1 }
}}

// $project: Transform fields
{ $project: {
  name: 1,
  email: 1,
  fullName: { $concat: ['$firstName', ' ', '$lastName'] },
  _id: 0
}}

// $sort: Sort results
{ $sort: { createdAt: -1 } }  // -1 for descending, 1 for ascending

// $limit and $skip: Pagination
{ $limit: 10 }
{ $skip: 20 }

// $unwind: Deconstruct arrays
{ $unwind: '$tags' }  // One document per tag

// $lookup: Join collections
{ $lookup: {
  from: 'categories',
  localField: 'categoryId',
  foreignField: '_id',
  as: 'category'
}}

// $facet: Multi-faceted search
{ $facet: {
  byCategory: [{ $group: { _id: '$category', count: { $sum: 1 } } }],
  byPrice: [{ $group: { _id: null, avg: { $avg: '$price' } } }]
}}

Aggregation Functions

javascript
// Numeric functions
{ $sum: 1 }                    // Count
{ $sum: '$amount' }            // Sum field
{ $avg: '$price' }             // Average
{ $min: '$quantity' }          // Minimum
{ $max: '$quantity' }          // Maximum

// Array functions
{ $push: '$tags' }             // Collect all values
{ $addToSet: '$category' }     // Collect unique values
{ $first: '$name' }            // First element
{ $last: '$name' }             // Last element

// String functions
{ $concat: ['$firstName', ' ', '$lastName'] }
{ $substr: ['$email', 0, 5] }
{ $toLower: '$name' }
{ $toUpper: '$name' }

// Conditional
{ $cond: [
  { $gte: ['$age', 18] },
  'Adult',
  'Minor'
]}

Real-World Examples

Sales Report by Category

javascript
await orders.aggregate([
  { $match: { status: 'completed' } },
  { $group: {
    _id: '$category',
    totalSales: { $sum: '$amount' },
    ordersCount: { $sum: 1 },
    avgOrderValue: { $avg: '$amount' }
  }},
  { $sort: { totalSales: -1 } }
]).toArray();

User Activity Summary

javascript
await users.aggregate([
  { $match: { lastActive: { $gte: new Date(Date.now() - 30*24*60*60*1000) } } },
  { $project: {
    name: 1,
    email: 1,
    lastActive: 1,
    daysInactive: {
      $floor: {
        $divide: [
          { $subtract: [new Date(), '$lastActive'] },
          1000 * 60 * 60 * 24
        ]
      }
    }
  }},
  { $sort: { daysInactive: 1 } }
]).toArray();

Join with Lookup

javascript
await orders.aggregate([
  { $match: { status: 'pending' } },
  { $lookup: {
    from: 'customers',
    localField: 'customerId',
    foreignField: '_id',
    as: 'customer'
  }},
  { $unwind: '$customer' },
  { $project: {
    orderId: '$_id',
    customerName: '$customer.name',
    total: '$amount',
    _id: 0
  }}
]).toArray();

Python Example

python
from pymongo import MongoClient

client = MongoClient('mongodb://localhost:27017')
collection = client['db']['collection']

pipeline = [
    {'$match': {'status': 'active'}},
    {'$group': {'_id': '$category', 'count': {'$sum': 1}}},
    {'$sort': {'count': -1}}
]

results = list(collection.aggregate(pipeline))
for doc in results:
    print(doc)

Performance Tips

✅ Use $match early to filter documents ✅ Avoid $project before necessary stages ✅ Use indexes on $match fields ✅ Use $limit before expensive operations ✅ Monitor aggregation performance ✅ Use $facet for parallel processing ✅ Avoid large $unwind operations

Recommended Agent Skills

Expand your agent's capabilities with these related and highly-rated skills.

pluginagentmarketplace/custom-plugin-mongodb

mongodb-find-queries

Master MongoDB find queries with filters, projections, sorting, and pagination. Learn query operators, comparison, logical operators, and real-world query patterns. Use when retrieving data from MongoDB collections.

1 0
Explore
pluginagentmarketplace/custom-plugin-mongodb

mongodb-index-creation

Master MongoDB index creation and types. Learn single-field, compound, unique, text, geospatial, and TTL indexes. Optimize query performance dramatically with proper indexing.

1 0
Explore
pluginagentmarketplace/custom-plugin-mongodb

mongodb-atlas-setup

Master MongoDB Atlas cloud setup, cluster configuration, security, networking, backups, and monitoring. Get production-ready cloud database in minutes. Use when setting up cloud MongoDB, configuring clusters, or managing Atlas.

1 0
Explore
pluginagentmarketplace/custom-plugin-mongodb

mongodb-replication-sharding

Master MongoDB replication, replica sets, and sharding for distributed deployments. Learn failover, shard keys, and cluster management. Use when setting up high availability or scaling horizontally.

1 0
Explore
pluginagentmarketplace/custom-plugin-mongodb

mongodb-crud-operations

Master MongoDB CRUD operations, document insertion, querying, updating, and deletion. Learn BSON format, ObjectId, data types, and basic operations. Use when working with documents, collections, and fundamental MongoDB operations.

1 0
Explore
pluginagentmarketplace/custom-plugin-mongodb

mongodb-indexing-optimization

Master MongoDB indexing and query optimization. Learn index types, explain plans, performance tuning, and query analysis. Use when optimizing slow queries, analyzing performance, or designing indexes.

1 0
Explore

Didn't find tool you were looking for?

Be as detailed as possible for better results