How can I run several async api functions, then call another function when all are complete?

Question

I'm using a node script to make several api calls asynchronously and now i need to 'do something' once those calls are done. Not sure what to do in my createProject() function after i perform the request, set the options and get doSomething AFTER the options are set.

function performRequest(reqOptions, reqBody, success) {
  const req = https.request(reqOptions, (res) => {
    var chunks= [];

    // data received
    res.on('data', function (chunk) {...});

    // data processed
    res.on('end', function() { success(Buffer.concat(chunks).toString()); });
  });

  // error occurred during request
  req.on('error', (e) => {
    console.error('Request error: ' + e);
  });

  req.write(JSON.stringify(reqBody));

  // end request
  req.end();
}

function createProject(name) {  
  var reqOptions = {...};
  var reqBody = {...};

  performRequest(reqOptions , reqBody , function(data) {
    // project successfully created - set project options
    setOption1(data.id);
    setOption2(data.id);

    // after options set, do something
    doSomething();

  });
}

function setOption1(id) {
  // performRequest(...)
}

function setOption2(id) {
  // performRequest(...)
}

function doSomething() { ... }

Use Promise.all (and make performRequest return a promise) — Bergi
– Bergi, Commented Nov 6, 2019 at 18:01

Wang Liang · Accepted Answer · 2021-09-10 14:20:46Z

2

We can make non-bloking function to blocking function using Promise, await, async

function performRequest(reqOptions, reqBody, success) { 
    return new Promise((resolve, reject) => {
        const req = https.request(reqOptions, (res) => {
            var chunks = [];

            // data received
            res.on('data', function (chunk) { });

            // data processed
            res.on('end', function () {
                resolve(Buffer.concat(chunks).toString());
            });
        })

        // error occurred during request
        req.on('error', (e) => {
            console.error('Request error: ' + e);
            reject(e);
        });

        req.write(JSON.stringify(reqBody));

        // end request
        req.end();
    });
}

async function createProject(name) {
    var reqOptions = { ...  };
    var reqBody = { ... };

    var data = await performRequest(reqOptions, reqBody);
    // project successfully created - set project options
    await setOption1(data.id);
    await setOption2(data.id);

    // after options set, do something
    doSomething();

}

async function setOption1(id) {
    return performRequest(...)
}

async function setOption2(id) {
    return performRequest(...)
}

function doSomething() {

}

edited Sep 10, 2021 at 14:20

answered Nov 6, 2019 at 18:04

Wang Liang

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1 Comment

Wang Liang Over a year ago

We have to use async for await.

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