JSON to dictionary in JavaScript?

Question

In my JS code, I need to convert the JSON response from server to a dictionary so that I can access them by key names. Here is the situation:

Say, this is the JSON response from my server:

{
   'status': 'success',
   'employees' : [
      { 'id': 12, 'name': 'Tom', 'department': 'finance' },
      { 'id': 34, 'name': 'Dick', 'department': 'admin' },
      { 'id': 56, 'name': 'Harry', 'department': 'marketing' }
   ]
}

Now what i need is to create a dictionary variable such that the key is the id and the value is the (say) name so that i can access them variable.id or variable[id_value] (from a loop).

How can this be achieved? Your help highly appreciated.

Thanks

nnnnnn · Accepted Answer · 2013-07-05 20:54:35Z

39

Note that that is not valid JSON: you have to use double-quotes, not single-quotes.

Assuming you fix that, and that the JSON has already been retrieved into a string variable jsonResult, you need to parse that to get an object using JSON.parse():

var result = JSON.parse(jsonResult);

You can build a dictionary from there:

var employees = {};

for (var i = 0, emp; i < result.employees.length; i++) {
   emp = result.employees[i];
   employees[ emp.id ] = emp;
}

console.log(employees[56].name);       // logs "Harry"
console.log(employees[56].department); // logs "marketing"

You said "and the value is the (say) name" - if you don't need the department values then in the for loop above say employees[ emp.id ] = emp.name; and then (obviously) employees[56] would give you "Harry" directly.

Demo: http://jsfiddle.net/RnmFn/1/

edited Jul 5, 2013 at 20:54

answered Jul 5, 2013 at 20:42

nnnnnn

150k30 gold badges210 silver badges247 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jonathan Lonowski · Accepted Answer · 2013-07-05 20:44:19Z

3

Well, assuming the JSON has already been parsed to an Object:

var data = JSON.parse('{"status":"success","employees":[{},{},{}]}'); // abridged

You can loop over data.employees to build the "dictionary" (Object):

var employees = {};

for (var i = 0; i < data.employees.length; i++) {
    employees[data.employees[i].id] = data.employees[i];
}

Then, given an employeeId:

var employee = employees[employeeId];

answered Jul 5, 2013 at 20:44

Jonathan Lonowski

124k35 gold badges203 silver badges202 bronze badges

Comments

Mark · Accepted Answer · 2013-07-05 20:53:31Z

1

You could write a javascript function to get an employee by id from a list of employees:

function getEmployee(id, employees) {
    for (var i = 0; i < employees.length; i++) {
        var employee = employees[i];
        if (employee.id === id) {
            return employee;
        }
    }

    return null;
}

and then use this function on the response you got from the server after parsing the JSON string back to a javascript object:

var json = 'the JSON string you got from the server';
var obj = JSON.parse(json);
var employees = obj.employees;
var employee = getEmployee(34, employees);
if (employee != null) {
    alert(employee.name);
}

edited Jul 5, 2013 at 20:53

Mark

1,1031 gold badge9 silver badges22 bronze badges

answered Jul 5, 2013 at 20:41

Darin Dimitrov

1.0m276 gold badges3.3k silver badges3k bronze badges

Comments

CRice · Accepted Answer · 2014-12-12 05:10:45Z

0

Something like this allows you to create a dictionary in one line, and specify the key and value used, or at least the key where the value becomes the entire object.

function toDictionary(items, key, value) {

    var dictionary = {};

    if (items) {
        for (var i = 0; i < items.length; i++) {
            var item = items[i];
            dictionary[key(item)] = value ? value(item) : item;
        }
    }

    return dictionary;
}

Example usage:

var dictionary = toDictionary(result.employees, function (record) { return record.id; });
var employee = dictionary[34];
if (employee) {
  // do something with employee object
}

edited Dec 12, 2014 at 5:10

answered Dec 12, 2014 at 5:02

CRice

12.6k7 gold badges60 silver badges91 bronze badges

Collectives™ on Stack Overflow

JSON to dictionary in JavaScript?

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related