makeExecutableSchema without graphql-tools

makeExecutableSchema.js

const { buildSchema } = require('graphql');
const express = require('express');
const { graphqlHTTP } = require('express-graphql');

const makeExecutableSchema = (schema, resolverMap) => {
  const executableSchema = buildSchema(schema);

  Object.keys(resolverMap).forEach(typeKey => {
    const fields = executableSchema.getType(typeKey).getFields();
    Object.keys(resolverMap[typeKey]).forEach(fieldKey => {
      fields[fieldKey].resolve = resolverMap[typeKey][fieldKey];
    });
  });

  return executableSchema;
};

// example usage
const schema = `
type Query {
  allTodoLists: [TodoList]
}

type TodoItem {
  text: String
  done: Boolean
}

type TodoList {
  title: String
  totalCount: Int
  notDoneCount: Int
  items: [TodoItem]
}
`;

const todoLists = [
  {
    title: '5 year plan',
    items: [
      { text: 'Get Married', done: false },
      { text: 'Have Babies', done: false },
    ],
  },
  {
    title: 'Grocery List',
    items: [
      { text: 'Potatoes', done: false },
      { text: 'Rum', done: true },
    ],
  },
];

const resolvers = {
  Query: {
    allTodoLists: () => todoLists,
  },
  TodoList: {
    totalCount: source => {
      return source.items.length;
    },
    notDoneCount: source => {
      return source.items.filter(item => !item.done).length;
    },
  },
};

makeExecutableSchema(schema, resolvers);

const app = express();

app.use(
  '/graphql',
  graphqlHTTP({
    schema: makeExecutableSchema(schema, resolvers),
    graphiql: true,
  })
);

app.listen(4000);

// example query
{
  allTodoLists {
    title
    totalCount
    notDoneCount
    items {
      text
      done
    }
  }
}

// example response
{
  "data": {
    "allTodoLists": [
      {
        "title": "5 year plan",
        "totalCount": 2,
        "notDoneCount": 2,
        "items": [
          {
            "text": "Get Married",
            "done": false
          },
          {
            "text": "Have Babies",
            "done": false
          }
        ]
      },
      {
        "title": "Grocery List",
        "totalCount": 2,
        "notDoneCount": 1,
        "items": [
          {
            "text": "Potatoes",
            "done": false
          },
          {
            "text": "Rum",
            "done": true
          }
        ]
      }
    ]
  }
}