// server.jsconst express = require('express');const { graphqlHTTP } = require('express-graphql');const { buildSchema } = require('graphql');const cors = require( `cors` );   // deals with Cross-Origin issuesvar fakeDatabase = [{sid:parseInt(Math.random()*10000),
                                name:'Philip',
                                subjects:['Chemistry', 'Physics', 'Maths'],
                                address:{
                                    unit: 'H505',
                                    city: 'London',
                                    country: 'United Kingdom',
                                    postCode: 33100}}];var schema = buildSchema(fs.readFileSync('schema.graphql','utf8'));// Each field is either a constant or a callbackvar root = {
  name: ()=>fakeDatabase[0].name,
  sid: arg => (arg.year+"-"+fakeDatabase[0].sid),
  subjects: fakeDatabase[0].subjects,
  address: () => ({
     city: ()=>fakeDatabase[0].address.city
  }),
  setName: arg => {fakeDatabase[0].name=arg.nn; return arg.nn;}};var app = express();app.use(cors());app.use('/graphql', graphqlHTTP({
  schema: schema,
  rootValue: root,
  graphiql: true,}));app.listen(4000);console.log('Running a GraphQL API server at http://localhost:4000/graphql');