graphql-add-middleware

import { buildSchema } from 'graphql'; import { addMiddleware } from 'graphql-add-middleware'; // Define a basic GraphQL schema const schemaString = ` type User { id: ID! name: String! } type Post { id: ID! title: String! author: User } type Query { users: [User!]! posts: [Post!]! } type Mutation { createUser(name: String!): User! } `; const schema = buildSchema(schemaString); // Add a global middleware for logging all resolver calls addMiddleware(schema, async (root, args, context, info, next) => { console.log(`[Global Middleware] Entering resolver: ${info.parentType}.${info.fieldName}`); const result = await next(); // Proceed to the next middleware or original resolver console.log(`[Global Middleware] Exiting resolver: ${info.parentType}.${info.fieldName}`); return result; // Ensure the result is returned }); // Add middleware specifically to 'Query' type resolvers addMiddleware(schema, 'Query', async (root, args, context, info, next) => { console.log(`[Query Middleware] Processing Query.${info.fieldName} with args:`, args); const result = await next(); return result; }); // Add middleware to a specific field: Mutation.createUser addMiddleware(schema, 'Mutation.createUser', async (root, args, context, info, next) => { // Example of authentication check if (!context || !context.userId) { throw new Error('Unauthorized: You must be logged in to create a user.'); } console.log(`[CreateUser Middleware] Attempting to create user: ${args.name}`); const newUser = await next(); console.log(`[CreateUser Middleware] User created with ID: ${newUser.id}`); return newUser; }); console.log('GraphQL schema with middleware applied successfully.'); // The 'schema' object can now be passed to a GraphQL server (e.g., Apollo Server, express-graphql)