Executes functions async series

Question

I'm trying to executes two functions async series with node.JS. But I don't understand to do this.

Now, I have:

function 1:

function search(client_id, callback) {
    clientRedis.keys('director:*', function (err, results) {
        results.forEach(function (key) {
            clientRedis.hgetall(key, function (err, obj) {
                //SAVE RESULT
                console.log('save');
            });
        });
    });
    callback(null, results);
}

function 2:

function range(client_id, callback) {
    //Sort my array
    callback(null, results);
}

And I call this functions here:

async.series([
    search(client_id),
    range(client_id);
], function (err, result) {
    console.log(err);
    console.log(result);
});

My problem: Second function is execute before the first because the first take more time. I need the result to first function to range my array with the function 2.

On a side note, are you aware that using redis.keys isn't recommended in production because it scans all the keys? — Zlatko
– Zlatko, Commented May 30, 2015 at 11:37
You're not gonna like the answer: it depends. What are you fetching there? Some object ids? Data? Ranged data, sets, serialized objects? — Zlatko
– Zlatko, Commented May 30, 2015 at 11:46
I make a list with hmset command. Inside I have this format: {ID, 'latitude', NUMBER, "longitude", NUMBER}. And I want to range by distance all IDs in this list But I can't make a "range" on a list hmset so I use a array with ZADD — Matthieu
– Matthieu, Commented May 30, 2015 at 12:23

zag2art · Accepted Answer · 2015-05-28 08:48:01Z

1

If you aren't going to use results of the first function inside the second one directly (only via redis) you can use something like this:

async.series([
    search.bind(null, client_id),
    range.bind(null, client_id)
], function (err, results) {
    console.log(err);
    console.log(results[0]); // for search results
    console.log(results[1]); // for range results
});

edited May 28, 2015 at 8:48

answered May 28, 2015 at 8:27

zag2art

5,2022 gold badges31 silver badges40 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Matthieu Over a year ago

Please, what is bind ?

zag2art Over a year ago

Read developer.mozilla.org/en/docs/Web/JavaScript/Reference/…

Amadan · Accepted Answer · 2015-05-28 07:30:08Z

search(client_id) and range(client_id) will execute immediately, have callback argument assigned to undefined then async.series will try to execute the results of those functions as a series, and probably fail because those aren't functions, but undefined. Or rather, it would, if the functions didn't try to do undefined(null, results).

Keep in mind, if f is a function, f(...) executes it. You need to pass functions themselves to async.series, not results of their execution.

async.series wants you to pass in an array or object of tasks, each task being function(callback) { ... }.

Thus, the following should help:

async.series([
     function(callback) { search(client_id, callback); },
     function(callback) { range(client_id, callback); }
]...)

If you were writing in Haskell, that supports currying, your code would have been correct; but in JavaScript, f(x)(y) is not the same thing as f(x, y).

You also don't call callback from inside the Redis success function, which will also mess up your timing.

throrin19 · Accepted Answer · 2015-05-28 07:31:51Z

You should use async.waterfall instead of async.series to get first function result in second function.

Runs the tasks array of functions in series, each passing their results to the next in the array. However, if any of the tasks pass an error to their own callback, the next function is not executed, and the main callback is immediately called with the error.

And, you have a big mistakes in your code. If I understand your code, you want go to the second function after modify all your results and return this for the second function right ? In this case, use async.each instead of result.forEach and call the callback after the async each :

function search(client_id, callback) {
    clientRedis.keys('director:*', function (err, results) {
        var savedElems = [];
        async.each(results, function (key, done) {
            clientRedis.hgetall(key, function (err, obj) {
                if (err) {
                    return done(err);
                }
                savedElems.push(obj);
                done();
            });
        }, function (err) {
            if (err) {
                return callback(err);
            }
            callback(null, savedElems);
        });
    });
}

Collectives™ on Stack Overflow

Executes functions async series

3 Answers 3

2 Comments

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Related