Permission Rules

Permission Rules sits at the heart of authorization in GraphQL. This guide walks through the concept step by step, with examples, a cheatsheet, and common mistakes to avoid.

Permission Rules Overview

Permission Rules is a building block you will reach for often in GraphQL. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn permission rules properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real GraphQL projects.

function requireAuth(context) {
  if (!context.user) {
    throw new GraphQLError('Not authenticated', {
      extensions: { code: 'UNAUTHENTICATED' },
    });
  }
}

const resolvers = {
  Query: { me: (_p, _a, ctx) => (requireAuth(ctx), ctx.user) },
};

Authentication runs in context; resolvers check the user before returning protected data.

Permission Rules Example

const typeDefs = gql`
  type Query { hello: String! }
`;
const resolvers = { Query: { hello: () => 'world' } };
const server = new ApolloServer({ typeDefs, resolvers });

Start from a minimal Permission Rules example and grow it only as needed.
Keep configuration explicit so Permission Rules behaves the same in every environment.
Name things clearly so teammates understand your Permission Rules at a glance.
Add tests around Permission Rules early to lock in expected behaviour.

GraphQL Cheatsheet

Quick GraphQL reference related to permission rules.

Concept	Example	Purpose
Schema	`type Query { user(id: ID!): User }`	Define the API shape
Resolver	`Query: { user: (_, { id }) => ... }`	Provide field data
Query	`query { user(id: 1) { name } }`	Read exactly what you need
Mutation	`mutation { createUser(input) { id } }`	Change data
Subscription	`subscription { postAdded { id } }`	Real-time updates
Context	`context: ({ req }) => ({ user })`	Auth and shared state
DataLoader	`loader.load(id)`	Batch to avoid N+1

How Permission Rules Works in GraphQL

Permission Rules fits into GraphQL's model of a single typed schema that clients query for exactly the data they need. The server resolves each requested field through resolver functions.

Authentication runs in context; resolvers check the user before returning protected data.

The schema is the contract between client and server.
Resolvers fetch data field by field, including nested types.
Clients request only the fields they use, avoiding over-fetching.
Context carries auth and shared services into every resolver.

Practical Guidance for Permission Rules

In production, permission rules should be efficient and secure. Batch data access with DataLoader, guard resolvers with authorization, and limit query depth and complexity.

Concern	Recommendation
N+1 queries	Batch with DataLoader
Security	Auth in context, depth/complexity limits
Errors	Typed GraphQLError with extension codes
Performance	Cache and paginate large lists

Common Mistakes

Skipping error handling and edge cases when wiring up permission rules.
Leaving permission rules untested, so regressions slip into production.
Over-engineering permission rules before you actually need the extra flexibility.
Ignoring documentation, which makes permission rules hard for the next developer to change.

Key Takeaways

Permission Rules is a core part of working effectively with GraphQL.
Start small and keep permission rules focused on a single responsibility.
Apply consistent patterns so permission rules scales across your project.
Test and document permission rules to keep it maintainable over time.

Pro Tip

Pair permission rules with automated tests from day one. It is far cheaper to catch GraphQL regressions in CI than in production.