Append some JSON objects to a single projection for mongoDB

Question

I have a JSON object with

parameters.projection = {"apples" : true}

parameters.projection = {"oranges" : true}

parameters.projection = {"lemons" : true}

I pass parameters to another function that makes the call to mongoDB

I need to combine those three elements above into a single projection objection that looks like

projection = {"apples" : true, "oranges" : true, "lemons" : true}

I have so far

var applyParameters = function(filter){

var params = {};

 for(var key in filter.projection){
    //What goes here to append them?
 }    

 return params;
};

No jquery and preferably no 3rd party libraries at all. Pure JavaScript please.

Does this works ? particularly the selected answer http://stackoverflow.com/questions/8430336/get-keys-of-json-object-in-javascript — Jorge Omar Vázquez, Jun 20 '14 at 20:48
@JorgeOmarVazquez Not quite. It has to be specifically in the format above. I figured it out though. — Chauncey Philpot, Jun 20 '14 at 21:05

score 0 · Accepted Answer · answered Jun 20 '14 at 21:07

This worked for me

var applyParameters = function(filter){

//Manually build the JSON object as a string
var params = "{";
var projection = filter.projection;

for(var key in projection){
    if (projection.hasOwnProperty(key)) {

        params += '"' + key + '" : ' + projection[key] + ',';
    }
}
//Make sure the projection object wasn't empty.
if(params.length > 1){
    //Strip the last comma off
    params = params.substring(0, params.length-1);
}    

params += "}";

return JSON.parse(params);
};

Append some JSON objects to a single projection for mongoDB

1 Answers1