nodejs-graphql-server-connect/server.ts at main · smart-developer1791/nodejs-graphql-server-connect · GitHub

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import http from 'http';
import connect from 'connect';
import { graphql, buildSchema } from 'graphql';

/*
|--------------------------------------------------------------------------
| GraphQL Schema Definition (SDL)
|--------------------------------------------------------------------------
| The schema describes:
| - Object types (User, Message)
| - Entry points (Query, Mutation)
| - Available fields and arguments
|
| buildSchema is used instead of makeExecutableSchema
| to keep the server minimal and dependency-free.
*/
const schema = buildSchema(`
  type User {
    id: ID!
    name: String!
    email: String!
  }

  type Message {
    message: String!
    timestamp: String!
  }

  type Query {
    hello: String!
    users: [User!]!
    user(id: ID!): User
  }

  type Mutation {
    sendMessage(message: String!): Message!
  }
`);

/*
|--------------------------------------------------------------------------
| In-memory Data Store (Mock Database)
|--------------------------------------------------------------------------
| This is a simple in-process data source.
| In real-world applications this would be replaced by:
| - a database
| - a microservice call
| - or a repository layer
*/
const USERS = [
  { id: '1', name: 'Alice', email: 'alice@example.com' },
  { id: '2', name: 'Bob', email: 'bob@example.com' },
  { id: '3', name: 'Carol', email: 'carol@example.com' },
];

/*
|--------------------------------------------------------------------------
| Root Resolver Map
|--------------------------------------------------------------------------
| Each function corresponds to a field in Query or Mutation.
| Resolvers are executed lazily only when requested by the client.
|
| rootValue is used instead of per-type resolvers
| to keep the example максимально простым.
*/
const root = {
  hello: () => 'Hello from GraphQL!',
  users: () => USERS,
  user: ({ id }: { id: string }) => USERS.find(u => u.id === id),
  sendMessage: ({ message }: { message: string }) => ({
    message,
    timestamp: new Date().toISOString(),
  }),
};

/*
|--------------------------------------------------------------------------
| Embedded GraphiQL UI
|--------------------------------------------------------------------------
| Served at GET /
| Provides an in-browser IDE for:
| - writing queries
| - running mutations
| - schema introspection
|
| No external backend dependencies required.
*/
const graphiqlHTML = `
<!DOCTYPE html>
<html>
  <head>
    <title>Node.js GraphQL Server</title>
    <link href="https://unpkg.com/graphiql@2.2.0/graphiql.min.css" rel="stylesheet" />
  </head>
  <body style="margin:0;height:100vh">
    <div id="graphiql" style="height:100vh"></div>

    <script src="https://unpkg.com/react@18/umd/react.production.min.js"></script>
    <script src="https://unpkg.com/react-dom@18/umd/react-dom.production.min.js"></script>
    <script src="https://unpkg.com/graphiql@2.2.0/graphiql.min.js"></script>

    <script>
      // GraphQL HTTP fetcher used by GraphiQL
      const fetcher = params =>
        fetch('/graphql', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify(params),
        }).then(res => res.json());

      // Mount GraphiQL UI
      ReactDOM.render(
        React.createElement(GraphiQL, { fetcher }),
        document.getElementById('graphiql')
      );
    </script>
  </body>
</html>
`;

/*
|--------------------------------------------------------------------------
| Minimal JSON Body Parser Middleware
|--------------------------------------------------------------------------
| Implemented manually to avoid external dependencies.
| - Consumes request stream
| - Parses JSON payload
| - Attaches result to req.body
|
| This middleware is intentionally POST-only.
*/
function jsonBodyParser(req: any, res: any, next: any) {
  if (req.method !== 'POST') return next();

  let body = '';

  req.on('data', (chunk: Buffer) => {
    body += chunk.toString();
  });

  req.on('end', () => {
    try {
      req.body = JSON.parse(body || '{}');
      next();
    } catch {
      res.statusCode = 400;
      res.end('Invalid JSON payload');
    }
  });
}

/*
|--------------------------------------------------------------------------
| Connect Application
|--------------------------------------------------------------------------
| Connect is a low-level middleware framework.
| Unlike Express, it supports only:
|   app.use(fn)
|   app.use(path, fn)
|
| Each middleware is a single function.
*/
const app = connect();

/*
|--------------------------------------------------------------------------
| GraphiQL Middleware
|--------------------------------------------------------------------------
| GET / → serves GraphiQL UI
*/
app.use('/', (req: any, res: any, next: any) => {
  if (req.method === 'GET' && req.url === '/') {
    res.setHeader('Content-Type', 'text/html');
    res.end(graphiqlHTML);
  } else {
    next();
  }
});

/*
|--------------------------------------------------------------------------
| GraphQL Endpoint Middleware Chain
|--------------------------------------------------------------------------
| POST /graphql
|  1) JSON body parsing
|  2) GraphQL execution
*/
app.use('/graphql', jsonBodyParser);

app.use('/graphql', async (req: any, res: any) => {
  if (req.method !== 'POST') {
    res.statusCode = 405;
    return res.end();
  }

  const { query, variables } = req.body;

  const result = await graphql({
    schema,
    source: query,
    rootValue: root,
    variableValues: variables,
  });

  res.setHeader('Content-Type', 'application/json');
  res.end(JSON.stringify(result));
});

/*
|--------------------------------------------------------------------------
| HTTP Server Bootstrap
|--------------------------------------------------------------------------
| The Connect app is passed directly into Node's HTTP server.
*/
http.createServer(app).listen(8080, () => {
  console.log('🚀 Server running at http://localhost:8080/');
});