Help with asynchronous method

[Duy Nguyen]

Hi,

I want to my code work as below:

1. save Chest object to db

2. Then save all contents belong to this chest to db (have logic to add new filed to content before saving)

3. Then return response with chest + new contents info

But the real code does not work as I expected, the code is:

chestApi = createChestWithContents{
    var chest = req.body;
    var contents = req.body.contents;
    chest.save(function(err, chest) {
           async.each(contents, function(content) {
                     content.save()....
            }, function(done) {
                   return res.status.(200).. ///OK
            });
    });
}

When I use postman to test, the method end up without any response returned due to asynchronous methods(even when I used async to wait till the loop finish), cannot figure out how to do those stuff synchronously.

--

Nguyen Hai Duy
Mobile : 0914 72 1900

Skype: nguyenhd2107

[Emanuele DelBono]

Probably you are using async.js in a wrong way. Do you call the "done callback" on after every save of the chest? The callback for async.each received 2 parameters, the item and the done callback.

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[Christopher Mina]

To be clear about Emanuele's response, the async API should look like this.

async.each(contents, function(content, cb) {
     content.save(function(err, resp) {

         cb(err); //lets hope err is null, but if it's not null, the err will get propagated through to the final "errors" param below.

     });
}, function(errors) {
    res.status.(200).. ///OK
});

-Chris

[Duy Nguyen]

Thanks Christopher and Emanuele.

I do not want to call cb after saving, mean that I just want to loop via list of contents, then save them, thats all.

async.each(contents, function(content, cb) {
     content.save(function(err, resp) {

         /*DO NOT NEE TO CALL cb HERE*/ cb(err); //lets hope err is null, but if it's not null, the err will get propagated through to the final "errors" param below.

     });
}, function(errors) {
    res.status.(200).. ///OK
});

Is it possible to apply async without cb param?

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[Christopher Mina]

You would simply just call save and then cb(). 

async.each(contents, function(content, cb) {
     content.save();

     cb();

}, function(errors) {
    res.status.(200).. ///OK
});

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Christopher Mina

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[Duy Nguyen]

It works, thank you so much Chris.

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