GraphQL API with Apollo Server

Create a production-ready GraphQL API for [Application] using Apollo Server.

Requirements

1. Schema Design

Define GraphQL schema with:

• [Number] main types representing [entities]
• Relationships between types
• Queries for data fetching
• Mutations for data modification
• Input types for complex arguments

2. Type Definitions

Create schema for:

• Query - Read operations ([operations])
• Mutation - Write operations ([operations])
• Subscription - Real-time updates (optional)
• Custom scalar types if needed

3. Resolvers Implementation

Implement resolvers for:

• All queries with proper data fetching
• All mutations with validation
• Nested field resolvers
• Error handling and validation
• Authentication/authorization checks

4. Performance Optimization

Include:

• DataLoaders to prevent N+1 queries
• Query complexity limits
• Depth limiting
• Caching strategies
• Pagination for lists

5. Context and Data Sources

Set up:

• Authentication context
• Database connections
• External API clients
• User permissions

6. Error Handling

Implement:

• Custom error types
• Proper error messages
• Error codes
• Stack traces in development only

Example Implementation

import { ApolloServer, gql } from "apollo-server"
import DataLoader from "dataloader"

// Schema
const typeDefs = gql`
  type [TypeName] {
    id: ID!
    [field]: String!
    [relationField]: [[RelatedType]!]!
  }

  type Query {
    [queryName](id: ID!): [TypeName]
    [listQuery]: [[TypeName]!]!
  }

  type Mutation {
    [mutationName](input: [InputType]!): [TypeName]!
  }

  input [InputType] {
    [field]: String!
  }
`

// Resolvers
const resolvers = {
  Query: {
    [queryName]: async (_, { id }, { dataSources }) => {
      return dataSources.[dataSource].getById(id)
    }
  },
  Mutation: {
    [mutationName]: async (_, { input }, { dataSources, user }) => {
      if (!user) throw new Error(`Not authenticated`)
      return dataSources.[dataSource].create(input)
    }
  },
  [TypeName]: {
    [relationField]: async (parent, _, { loaders }) => {
      return loaders.[loader].load(parent.id)
    }
  }
}

// DataLoader for N+1 prevention
const create[Entity]Loader = () => new DataLoader(async (ids) => {
  const items = await db.[table].findMany({ where: { id: { in: ids } } })
  return ids.map(id => items.find(item => item.id === id))
})

// Server
const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: ({ req }) => ({
    user: req.user,
server.listen().then(({ url }) => {
  console.log(`Server ready at ${url}`)
})