CODEWITHSUNDEEP
javascriptnode.js
TRG
TRG

Reputation: 13

Chaining promises which read a console input

I'm trying to chain some promises that which one read an input from console and passes the result to the next one into an object. The problem is I get undefined in the second promise and promises don´t chain.

const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

const getUrl = (objectInfo) =>{
    return new Promise((resolve) => {
        rl.question('Introduce post URL ', (answerUrl) => {
            console.log(answerUrl);
            rl.close();
            objectInfo.url = answerUrl;
            resolve(objectInfo);
        });
    });
};

const getFieldsToFill = (objectInfo) => {
    new Promise((resolve) => {
        rl.question('Introuce fields with spaces', (answerFields) => {
            console.log(answerFields);
            rl.close();
            objectInfo.answerFields = answerFields;
            resolve(objectInfo);
        });
    }); 
};

const getFieldsType = (objectInfo) => {
    new Promise((resolve) => {
        rl.question('Introduce types ', (answerTypes) => {
            console.log(answerFields);
            rl.close();
            objectInfo.types = answerTypes
            resolve(objectInfo);
        });
    });
} 

getUrl({})
    .then(getFieldsToFill)
    .then(getFieldsType)
    .then((information) => {
        console.log(information)
    });

Upvotes: 0

Views: 193

Answers (2)

Brett Beatty
Brett Beatty

Reputation: 5983

Your functions aren't actually returning the promises. They're of the format

const someFunction = (objectInfo) => {
    new Promise(//...

But should be of the format

const someFunction = (objectInfo) =>
    new Promise(//...

or

const someFunction = (objectInfo) => {
    return new Promise(//...

Upvotes: 0

Alberto Trindade Tavares
Alberto Trindade Tavares

Reputation: 10366

There were two problems in your code:

  1. Missing return statement in getFieldsToFill and getFieldsType
  2. You were closing the readline before reading more answers

Here is the code with those fixes:

const readline = require('readline');

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

const getUrl = (objectInfo) =>{
    return new Promise((resolve) => {
        rl.question('Introduce post URL ', (answerUrl) => {
            console.log(answerUrl);
            objectInfo.url = answerUrl;
            resolve(objectInfo);
        });
    });
};

const getFieldsToFill = (objectInfo) => {
    return new Promise((resolve) => {
        rl.question('Introuce fields with spaces', (answerFields) => {
            console.log(answerFields);
            objectInfo.answerFields = answerFields;
            resolve(objectInfo);
        });
    }); 
};

const getFieldsType = (objectInfo) => {
    return new Promise((resolve) => {
        console.log(objectInfo);
        rl.question('Introduce types ', (answerTypes) => {
            rl.close();
            objectInfo.types = answerTypes
            resolve(objectInfo);
        });
    });
}; 

getUrl({})
    .then(getFieldsToFill)
    .then(getFieldsType)
    .then((information) => {
        console.log(information)
    });

Upvotes: 1

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