How to fetch the data from database for resolver in graphql - node.js

Question

I Have Created two File
index.js
const {ApolloServer,gql} = require('apollo-server');
const fs = require('fs');
const path = require('path');
const typedefs = gql`
type Query {
info: String!
ask: [Person!]
}
type Person {
name: String!
age: Int!
}
`;
const resolvers = {
Query: {
info: () => `Hello World from Linux Fan`,
ask: () => {
return [fs.readFileSync(__dirname+path.join('/db.db'),'utf-8')]
}
}
}
const server = new ApolloServer({
typedefs,
resolvers
}).listen().then(({url}) => console.log(url)).catch(err => console.log(err));
and one More File for storing Database
db.db
{
name:"Linux Age",
age: 19
}
But The Problem is everytime I make a query for fetching name and age like
{
info
ask{
name
}
}
There is a problem which exist and say
"Cannot return null for non-nullable field Person.name"
How to Solve ??

Answer 1

According to Node.js documentation (https://nodejs.org/api/fs.html#fs_fs_readfilesync_path_options), fs.readFileSync() returns a String or Buffer. From the schema, however, ask() returns an array of type Person which is an object. The result of fs.readFileSync() should be converted to object before returning:
ask: () => {
const person = JSON.parse(JSON.stringify(
fs.readFileSync(__dirname + path.join('/db.db'), 'utf-8').toString()
));
return [person];
}
Notice that I called JSON.stringify() before parsing it with JSON.parse(). The reason is the file db.db has a javascript object (keys, nanely name and age, without double quotes around them) and not a JSON object (keys with quotes as shown below):
{
"name":"Linux Age",
"age": 19
}
Otherwise, JSON.parse() would have a problem parsing the invalid JSON format:
{
name:"Linux Age",
age: 19
}
In addition, toString() after calling readFileSync() is needed to convert a Buffer to a string:
fs.readFileSync(__dirname + path.join('/db.db'), 'utf-8').toString()