Question

151

Nodejs calling function from within a function

rated 0 times [ 156] [ 5] / answers: 1 / hits: 15463 / 12 Years ago, fri, december 7, 2012, 12:00:00

I have 3 methods

exports.getImageById = function (resultFn, id) {

 ...

}



exports.getCollectionById = function (resultFn, id) {

}

in the third method I want to call both methods

exports.getCollectionImages = function (resultFn, collectionId) {



var arr = new Array();



this.getCollectionById(   // fine, 1st call

    function (result) {

        var images = result.image;

        for (i = 0; i < images.length; i++) {

            this.getImageById(function (result1) {   // error, 2nd call

                    arr[i] = result1;

                }, images[i]

            );



         }

    }

    , collectionId

);



resultFn(arr);

}

I can call first function this.getCollectionById but it fails to call this.getImageById, it says undefined function, whats the reason for that?

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zaynerogerb

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answered 12 Years ago dajah · Accepted Answer

When you call this.getCollectionById passing it a callback, the callback doesn't have access to the same this

The simplest solution is to save this as a local variable.

exports.getCollectionImages = function (resultFn, collectionId) {    

    var arr = new Array();        

    var me = this; // Save this

    this.getCollectionById(   // fine, 1st call

        function (result) {

            var images = result.image;

            for (var i = 0; i < images.length; i++) {

                // Use me instead of this

                me.getImageById(function (result1) {   // error, 2nd call

                    arr[i] = result1;

                }, images[i]);

            }

        }, collectionId);

    resultFn(arr);

}