MongoDB / Mongoose Patterns

Quick Guide: Use Mongoose as the ODM for MongoDB. Define schemas with automatic TypeScript inference, use lean() for read-only queries, prefer embedding over referencing for co-accessed data, place $match early in aggregation pipelines, and always define indexes to match your query patterns.

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CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST define Mongoose middleware (pre/post hooks) BEFORE calling model() -- hooks registered after model compilation are silently ignored)

(You MUST pass { session } to EVERY operation inside a transaction -- missing session causes operations to run outside the transaction)

(You MUST use .lean() for read-only queries that send results directly to API responses -- skipping lean wastes 3x memory on hydration overhead)

(You MUST use 127.0.0.1 instead of localhost in connection strings -- Node.js 18+ prefers IPv6 and localhost can cause connection timeouts)