mongo-aggregate
Execute aggregation pipelines on MongoDB collections to process and analyze data through multiple transformation stages for complex querying and reporting.
Instructions
Execute aggregation pipeline on a MongoDB collection
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| collection | Yes | Collection name | |
| database | Yes | Database name | |
| pipeline | Yes | Aggregation pipeline as array of stage objects |
Input Schema (JSON Schema)
{
"properties": {
"collection": {
"description": "Collection name",
"type": "string"
},
"database": {
"description": "Database name",
"type": "string"
},
"pipeline": {
"description": "Aggregation pipeline as array of stage objects",
"items": {
"additionalProperties": {},
"type": "object"
},
"type": "array"
}
},
"required": [
"database",
"collection",
"pipeline"
],
"type": "object"
}
Implementation Reference
- src/index.ts:241-261 (handler)Executes the MongoDB aggregation pipeline: connects to DB, runs aggregate on collection, formats output using helper functions, returns formatted result or throws error.async ({ database: dbName, collection: collectionName, pipeline }) => { try { const db = await ensureConnection(dbName); const collection: Collection = db.collection(collectionName); const documents = await collection.aggregate(pipeline).toArray(); const formattedOutput = formatJsonOutput(documents); return { content: [ { type: "text", text: `Aggregation returned ${documents.length} document(s):\n\n${formattedOutput}`, }, ], }; } catch (error) { throw new Error(`Failed to execute aggregation: ${error instanceof Error ? error.message : 'Unknown error'}`); } }
- src/index.ts:236-240 (schema)Zod schema defining input parameters for the tool: database name, collection name, and aggregation pipeline array.{ database: z.string().describe("Database name"), collection: z.string().describe("Collection name"), pipeline: z.array(z.record(z.any())).describe("Aggregation pipeline as array of stage objects"), },
- src/index.ts:233-262 (registration)Registers the 'mongo-aggregate' tool with MCP server, providing name, description, input schema, and handler function.server.tool( "mongo-aggregate", "Execute aggregation pipeline on a MongoDB collection", { database: z.string().describe("Database name"), collection: z.string().describe("Collection name"), pipeline: z.array(z.record(z.any())).describe("Aggregation pipeline as array of stage objects"), }, async ({ database: dbName, collection: collectionName, pipeline }) => { try { const db = await ensureConnection(dbName); const collection: Collection = db.collection(collectionName); const documents = await collection.aggregate(pipeline).toArray(); const formattedOutput = formatJsonOutput(documents); return { content: [ { type: "text", text: `Aggregation returned ${documents.length} document(s):\n\n${formattedOutput}`, }, ], }; } catch (error) { throw new Error(`Failed to execute aggregation: ${error instanceof Error ? error.message : 'Unknown error'}`); } } );
- src/index.ts:88-100 (helper)Helper function to ensure MongoDB client connection and retrieve or create database instance, used by all tools including mongo-aggregate.async function ensureConnection(dbName: string): Promise<Db> { if (!mongoClient) { const uri = getMongoUri(); mongoClient = new MongoClient(uri); await mongoClient.connect(); } if (!databases.has(dbName)) { databases.set(dbName, mongoClient.db(dbName)); } return databases.get(dbName)!; }
- src/index.ts:64-78 (helper)Helper function to format and truncate large JSON outputs for tool responses, used in mongo-aggregate to handle aggregation results.function formatJsonOutput(data: unknown): string { const truncatedData = truncateForOutput(data); let outputText = JSON.stringify(truncatedData, null, 2); outputText = outputText.replace( /"\.\.\.(\d+) more items"/g, "...$1 more items" ); outputText = outputText.replace( /"\.\.\.(\d+) more properties": "\.\.\.?"/g, "...$1 more properties" ); return outputText; }