Rewrite function to await about asyncawait HOT 6 CLOSED

Does connection.query also return a promise? If not, you'll have to make a version that does return a promise first. I don't know what DB library you are using so I'll assume it doesn't return promises. knex.js returns Promises so if you can use that I recommend it, as the code will interoperate much more easily with async/await style.

Anyhow, if your connection.query method only takes callbacks, then do something like this first:

// NB: if you are using iojs, Promise is already defined as a global
var Promise = require('bluebird');

function getTitles() {
    return new Promise(function (resolve, reject) {
        connection.query('SELECT * FROM titles', function (err, rows) {
            if (err) return reject(err);
            resolve(rows);
        });
    });
}

Then you can write some other async function that calls getTitles like this:

var doStuffAsync = async (function () {
    ...
    var titles = await (getTitles());
    ...
    var result = someOtherFunc(titles);
    return result;
});

When called, doStuffAsync will return a promise of its result.

On the other hand, if connection.query returned a promise directly, you wouldn't need getTitles at all, you could just do:

var doStuffAsync = async (function () {
    ...
    var titles = await (connection.query('SELECT * FROM titles'));
    ...
    var result = someOtherFunc(titles);
    return result;
});

from asyncawait.

Thanks! tomorrow, as will certainly try and describe the time.
ps its mysql connection https://www.npmjs.com/package/mysql

from asyncawait.

FYI, there are some promise-oriented wrappers for the mysql library:

• mysql-promise
• promise-mysql

I suggest using one of these, since they will work directly with async/await. No need to manually wrap or 'promisify' anything.

from asyncawait.

I get to set the old python. I liked more your way, but tell me if I can call a doStuffAsync func in addition? Why it again operates asynchronously, and I do not get the desired result (

from asyncawait.

doStuffAsync() is an ordinary (but asynchronous) function that returns a promise. The promise instance is what you can see in your screenshot above.

You need to await the asynchronous function call to suspend the caller until the promise resolves - ie titles = await (doStuffAsync()).

It's important to understand that to use await you need to be inside the definition of another async function. That is because suspending a function requires some kind of coroutine support, which normal functions do not provide, hence the async wrapper function.

That means that your outermost layer of functionality (perhaps the API you expose to your module's consumers) would still expose promise-returning functions.

So if doStuffAsync() was some public method, consumers would use it like a normal promise-returning function, ie doStuffAsync().then(function (result) { ... }).

from asyncawait.

Closing this as there seems no further action to be taken. Feel free to open another issue if you have more questions.

from asyncawait.