How do I create an array of objects in json?

Question

I have a json object as shown.

this.model = {
            "cellType": "RemoveCell",
            "maxWidth": "800px",
            "items": {
                "columns" : [
                    {"attribute": "existingStrings", "title": "Existing Strings"},
                ],
                "rows" : [
                    {"existingStrings": this.stringList},
                ]
            }
        },

this.stringList is an array of strings (of varying size). How do declare this.stringList in the JSON object so that it behaves in this manner below?

this.model = {
            "cellType": "RemoveCell",
            "maxWidth": "800px",
            "items": {
                "columns" : [
                    {"attribute": "existingStrings", "title": "Existing Strings"},
                ],
                "rows" : [
                    {"existingStrings": this.stringList[0]},
                    {"existingStrings": this.stringList[1]},
                    {"existingStrings": this.stringList[2]},
                                      ...
                                      ...
                    {"existingStrings": this.stringList[n]},
                ]
            }
        },

I want "rows" to contain an array of objects (one object for each element in stringList). Thanks

But I can't iterate in a json object. This is fine if the size of the array is constant and known. In my case it is not. I can't hardcode it like this. Thanks — kellzerIrl
– kellzerIrl, Commented Aug 7, 2014 at 16:19
do a foor loop on this.model.items.rows.existingStrings.length, and build the array of objects you need — BeNdErR
– BeNdErR, Commented Aug 7, 2014 at 16:20

Travis J · Accepted Answer · 2014-08-07 16:30:27Z

4

Use a function to build the list of objects

this.model = {
        "cellType": "RemoveCell",
        "maxWidth": "800px",
        "items": {
            "columns" : [
                {"attribute": "existingStrings", "title": "Existing Strings"},
            ],
            "rows" : 
                (function(){ 
                  var objList = []; 
                  for(var i = 0; i < this.stringList.length; i++)
                   objList.push({"existingStrings":this.stringList[i]});
                  return objList;
                })()
        }
    },

This works by using an IIFE (Immediately invoked function expression) as the value for "rows". (function(){}) defines the function expression. When the () is used following the expression the function is invoked. Inside of the function is a for loop which builds an array of objects using this.stringList. Once the loop finishes, the array is returned, and that is the value which is assigned to "rows".

edited Aug 7, 2014 at 16:30

answered Aug 7, 2014 at 16:21

Travis J

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4 Comments

dgiugg Over a year ago

May be useful to precise to the reader that you will then have to call your array using this.model.items.rows() instead of this.model.items.rows.

Travis J Over a year ago

@dgiugg - That is incorrect. The function is an immediately invoked function expression and evaluates to the array of objects.

Razzildinho Over a year ago

This is a more elegant answer than mine. You've left out the length attribute in the for loop though - this.stringList.length.

Travis J Over a year ago

I added a slight explanation of the process below, and also included .length (thanks for catching that).

Razzildinho · Accepted Answer · 2014-08-07 16:23:37Z

2

var rows = [];

for ( var i=0; i<this.stringList.length; i++){
    rows.push({"existingStrings":this.stringList[i]});
}

this.model = {
        "cellType": "RemoveCell",
        "maxWidth": "800px",
        "items": {
            "columns" : [
                {"attribute": "existingStrings", "title": "Existing Strings"},
            ],
            "rows" : rows
        }
    },

answered Aug 7, 2014 at 16:23

Razzildinho

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