With NodeJS version 16.14.0 I'm trying to migrate from a promise .then().catch to a async/await management.
The problem is that with the first method, I was able to chain multiple functions sequentially, with the same big object passed through each of it (with return resolve(bigObject) and each function taking as input the same bigObject). I was doing this because I'm able to manage micro-errors inside the data (so no catch involved), returning the user a full list of errors:

var commonData = {
    data1: ...
    data2: ...
    data3: ...
    data4: ...
    data5: ...
    data6: ...
};

return function1(commonData)
.then(function2)
.then(function3)
.then(function4)
.then(function5)
.then(function(result) {
    //Inside this .then, I'd have the "result" variable as result of the chain
})
.catch(error => { return reject(error); });

How can I do it with async await system? This is what I've tried so far:

var commonData = {
    data1: ...
    data2: ...
    data3: ...
    data4: ...
    data5: ...
    data6: ...
};

commonData = await function1(commonData);
commonData = await function2(commonData);
commonData = await function3(commonData);
commonData = await function4(commonData);
commonData = await function5(commonData);

//I was expecting to have inside "commonData" the same situation 
//as "result" in the chain above

Is there another way to chain functions with the same big object passed through that I'm missing?

EDIT:
2 of the functions I'm using in this part...they are designed this way because they are being called in other parts of the file too, I couldn't use them locally

//function 1
async function function1(commonData) {
    try {
        var data1 = await models.data1.findAll({where: {Domain_ID: [13,15]}})
        data1.forEach(function(dat) {
            commonData.data1.push(dat.dataValues);
        });
        
        return commonData;
    } catch (error) {
        throw error;
    }
}

//function2
async function function2(commonData) {
    try {
        var data2 = await models.data2.findAll();
        data2.forEach(function(dat) {
            commonData.data2.push(dat.dataValues);
        });
        
        return commonData;
    } catch (error) {
        throw error;
    }
}

CodePudding user response：

No, there´s no other way. One of the reasons why Async/Await was implemented is that Promise chaining can look pretty ugly and messy. If you prefer .then(), just stick with it in this module.

For further reading: https://blog.logrocket.com/promise-chaining-is-dead-long-live-async-await-445897870abc/

CodePudding user response：

The way you have it (commonData = await function1(commonData), etc.) is just fine. But if you don't want to do that, you could nest the calls:

const result = await function5(
    await function4(
        await function3(
            await function2(
                await function1(commonData)
            )
        )
    )
);

Or use a loop:

let result = commonData;
for (const fn of [function1, function2, function3, function4, function5]) {
    result = await fn(result);
}

Or you could keep using then. Although in general mixing async/await with explicit promise handlers via .then/.catch is confusing, there are some limited times where you might do it:

const result = await function1(commonData)
    .then(function2)
    .then(function3)
    .then(function4)
    .then(function5);

It works because async functions are just a way to consume and produce promises.

---

Or with the very big caveat that you know that the functions only modify the state of the object and don't return (fulfill their promise with) a different object, you could do:

await function1(commonData);
await function2(commonData);
await function3(commonData);
await function4(commonData);
const result = await function5(commonData);

but it's a big caveat.

CodePudding user response：

Try to use Promise.all method

more infos here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all?retiredLocale=it