async each callback is called before iteration

Question

i have the following routing function:

router.route('/api/teamUsersWithStat/:team_id')
.get(function (req, res) {
    var user_stat = academy_team_user_stat.build();
    user_stat.usersByTeam(req.params.team_id, function (result) {
        if (result) {
            async.each(result, function () {
                var i = 0;
                user_stat.findModulesTaken(res.user_id, res.team_id, function (modules) {
                    result[i].modules = modules;
                    i++;
                });
            }, res.json(result))

        } else {
            res.status(401).send("Team not found");
        }
    }, function (error) {
        res.send("Team not found");
    });
});

as you can see im using the async.each method to collect additional data to my existing array.

However the res.json(result) is called without it running the actual loop.

(i can tell this as in my javascript i am debugging the response).

So what am i doing wrong?

Ben Fortune · Accepted Answer · 2015-04-16 12:52:29Z

3

You're calling your res.json method straight away, you're also reinitializing i inside the loop so it's always 0.

Also, each requires a callback in order to procede to the next iteration.

The following is how I'd do it:

async.each(result, function (r, callback) {
    user_stat.findModulesTaken(res.user_id, res.team_id, function (modules) {
        result[result.indexOf(r)].modules = modules;
        callback();
    });
}, function(err) {
    if(err)
        return res.json(err);
    res.json(result);
});

edited Apr 16, 2015 at 12:52

answered Apr 16, 2015 at 12:35

Ben Fortune

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Comments

Tim S. · Accepted Answer · 2015-04-16 12:33:21Z

0

res.json(result) is called as a function, and therefore invoked immediately. To make sure res.json is invoked after the async.each(), you need to pass a function as callback:

async.each(result, function () {
    ...
}, function(err) {
    if(!err) res.json(result);
));

answered Apr 16, 2015 at 12:33

Tim S.

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