Convert object to array for storage and back to array for application in JavaScript

Question

I have an object like this that's generated from dynamic checkboxes in angular:

{"United States":true,"Canada":true,"Australia":false}

It works great as far as storing the values, but to be able to do database searches for the country values, I want to be able to convert it to an array to save it to the database (MongoDb/Mongoose) like:

["United States":true,"Canada":true,"Australia":false]

And then convert it back to the exact same type of object for the application.

What would be the easiest way to do this?

I don't think ["United States":true,"Canada":true,"Australia":false] has the correct syntax for an array. — Pang
– Pang, Commented Dec 4, 2015 at 2:03
Underscore or Lodash: _.pairs(myObj) Assuming you want pairs — Luke
– Luke, Commented Dec 4, 2015 at 2:06
Well I don't necessarily need the :true part for the array, I would only need to store the true values... the most important thing is that I would be able to store it as an array and then be able to convert it back to the same object if I retrieved it from the database. — Anthony
– Anthony, Commented Dec 4, 2015 at 2:19
If you only store true values you change the number of values you're storing & could not accurately recreate the original object. Why can't you store the object in Mongo? mongodb.github.io/node-mongodb-native/api-articles/… — mc01
– mc01, Commented Dec 4, 2015 at 2:29
LukeP, using the _.pair(myObj) function seems easy enough in underscore. Do they have a similar command to convert the result back to an object? — Anthony
– Anthony, Commented Dec 4, 2015 at 2:32

bob · Accepted Answer · 2015-12-04 03:00:59Z

1

I might interpolate the values as:

"string", boolean, "string", boolean, "string", boolean

To do this:

// Taking the object...
var countryObject = {"United States":true,"Canada":true,"Australia":false};

// ... and simplifying for explanation as:
var countryObject = {"A":true,"B":true,"C":false};

var compact = [];
for(var prop in countryObject){
    compact.push( prop );
    compact.push( countryObject[prop] );
}

// compact yields interpolated values as a basic array:
// ["A", true, "B", false, "C", true];

FYI: You can now search the array quite efficiently by finding the index of the string value and then adding 1 to retrieve the boolean value by adding 1:

var foundIndex = compact.indexOf("B");
var result;
if(foundIndex > -1){
    result = countryArray[foundIndex + 1];
}

To piece back together:

var compact = ["A", true, "B", false, "C", true];
var countryObject = {};
for(var i=0; i<compact.length; i+= 2){
    countryObject[compact[i]] = compact[i+1];
}

answered Dec 4, 2015 at 3:00

bob

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1 Comment

Anthony Over a year ago

Thank you so much, your solution works like a charm.

Comptonburger · Accepted Answer · 2015-12-04 02:03:25Z

1

What you're asking for doesn't really make sense because the array you demonstrated is an associative array with key:value pairs, which in JavaScript, is an object.

You can create an array and assign it key:value pairs like so:

var a = [];
a['test'] = 1;

However, that is just playing on the fact that arrays are objects in JavaScript.

answered Dec 4, 2015 at 2:03

Comptonburger

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1 Comment

Anthony Over a year ago

Well do you know what would be a way to only store the countries that are true as an array, then convert it back to a similar object as the original when needed for the application?

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