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javascriptnode.jsbluebird

Loop asynchronous call and join the returned promise

I'm working on my first nodejs application which is using bluebird. I've a requirement to call an asynchronous method inside a for loop which returns a promise for each call. I want to combine all those promises together, how can I achieve this. Any help is much appreciated.

I'm retrieving set of documents from mongodb and I need to loop through that returned set of documents and pass a field as a parameter to an asynchronous method which returns a promise. Since i'm doing this in the loop I need a way to combine all of those promises in to one single promise.

Solution

  • You can use the .all() method : http://bluebirdjs.com/docs/api/promise.all.html

    Example :

    var promises = [];

for (var i = 0; i < 100; ++i) {
    promises.push(yourPromise);
}

Promise.all(promises).then(function(values) {
    // All your promises are resolved
    // Promises results are stored in values argument
    console.log(values);
});