Heldinhow GraphQL API
Overview
GraphQL provides a flexible query language for APIs with precise data requirements. This skill should be invoked when building flexible APIs needing nested data fetching, multiple data source aggregation, or client-controlled queries.
Core Principles
- Schema-Driven: Define types, queries, mutations in schema
- Resolver Implementation: Map schema fields to data sources
- DataLoader: Prevent N+1 queries with batching
- Validation: Validate inputs and handle errors properly
Preparation Checklist
- Choose GraphQL server (Apollo, GraphQL Yoga, Mercury)
- Design schema with types, queries, mutations
- Plan resolver structure
- Set up DataLoader for optimization
Step-by-Step Process
- Define Schema: Write SDL with types, queries, mutations
- Implement Resolvers: Create resolver functions
- Optimize: Add DataLoader for batching
- Validate: Add input validation
- Document: Set up Playground/GraphiQL
- Monitor: Add query complexity analysis
Do's and Don'ts
- ✅ Do use DataLoader to prevent N+1 queries
- ✅ Do validate all inputs
- ✅ Do set query complexity limits
- ❌ Don't expose internal database IDs
- ❌ Don't skip error handling
- ❌ Don't allow unbounded queries
Anti-Patterns
- N+1 Queries: Not using DataLoader
- No Limits: Allowing unbounded queries
- Internal Exposure: Leaking implementation details
- Error Leaks: Exposing stack traces