Heldinhow/graphql-api

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

1. Define Schema: Write SDL with types, queries, mutations
2. Implement Resolvers: Create resolver functions
3. Optimize: Add DataLoader for batching
4. Validate: Add input validation
5. Document: Set up Playground/GraphiQL
6. 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