Apollo-GraphQL-Books

index.js

const { ApolloServer, gql } = require('apollo-server');

// Type definitions define the "shape" of your data and specify
// which ways the data can be fetched from the GraphQL server.
const typeDefs = gql`
  # Comments in GraphQL are defined with the hash (#) symbol.
  # This "Book" type can be used in other type declarations.
  type Book {
    title: String!
    author: String
    createdAt: String
  }
  type BookInfo {
    totalBooks: Int
    recentlyAdded: Int
  }
  # The "Query" type is the root of all GraphQL queries.
  type Query {
    books: [Book!]!
  }
  # The "input" type used when you want to pass in a whole object to be created
  input BookInput {
    title: String!
    author: String!
  }
  # The "Mutation" type is one of the root GraphQL types.
  type Mutation {
    addBook(book: BookInput!): BookInfo!
  }
`;

// This is a (sample) collection of books we'll be able to query
// the GraphQL server for.  A more complete example might fetch
// from an existing data source like a REST API or database.
const books = [
    {
        title: 'Harry Potter and the Chamber of Secrets',
        author: 'J.K. Rowling',
        createdAt: 'Sun, 28 Oct 2018 18:53:25 GMT'
    },
    {
        title: 'Jurassic Park',
        author: 'Michael Crichton',
        createdAt: 'Sun, 28 Oct 2018 18:53:25 GMT'
    },
];

// This function returns a predicate
const predicate = currentDate => (counter, { createdAt }) => new 
Date(createdAt).getTime() + 3000 > currentDate.getTime() && counter + 1

// Resolvers define the technique for fetching the types in the
// schema.  We'll retrieve books from the "books" array above.
const resolvers = {
    Query: {
        books: () => books,
    },
    Mutation: {
        addBook: (obj, { book: { title, author } }) => {
            const date = new Date();
            const reducer = predicate(date)

            books.push({ title, author, createdAt: date.toUTCString() })

            const recentlyAdded = books.reduce(reducer, 0)

            return {
                totalBooks: books.length,
                recentlyAdded: recentlyAdded
            }
        },
    }
};

// In the most basic sense, the ApolloServer can be started
// by passing type definitions (typeDefs) and the resolvers
// responsible for fetching the data for those types.
const server = new ApolloServer({ typeDefs, resolvers });

// This `listen` method launches a web-server.  Existing apps
// can utilize middleware options, which we'll discuss later.
server.listen().then(({ url }) => {
    console.log(`рџљЂ  Server ready at ${url}`);
});