Create JSON in Javascript

Question

I would like to create a dynamic JSON array in Javascript like that :

var jsonData = {
    "Tasks" : [
        {
            "__metadata" : {
                "uri" : "...",
                "type" : "..."
            },
            "ID" : "...",
            "Category" : "..",
            // ...
        },
        {
            "__metadata" : {
                "uri" : "...",
                "type" : "..."
            },
            "ID" : "...",
            "Category" : "..",
            // ...
        },
        // others tasks
    ], "__count" : "2"
};

I found how to create a JSON in Javascript but not with this syntax. So what is the good way to create the JSON object with the 'Tasks' array and add items in it ?

Thank you for your help

your question doesn't make sense. you already have the javascript you want, all you need to call is JSON.stringify() on it and you're done. — kennypu
– kennypu, Commented Mar 11, 2013 at 9:53
Also the __count attribute is redundant. It is already stored within the Tasks array. — Amberlamps
– Amberlamps, Commented Mar 11, 2013 at 9:56
This is an object literal, not JSON. Please use the correct terminology, otherwise it is difficult to understand your problem. But I believe the answer is: you can't. You can create the initial object with an object literal and then add the data to the array later. — Felix Kling
– Felix Kling, Commented Mar 11, 2013 at 10:01

Srikanth Venugopalan · Accepted Answer · 2013-03-11 10:03:23Z

1

Something like this maybe?

function Metadata(uri,type)
{
    this.uri = uri;
    this.type = type;
}

function Task(metadata, id, category)
{
    this.__metadata = metadata;
    this.ID = id;
    this.Category = category;
}

var tasks = [new Task(new Metadata('foo','bar'), 1, 'blah'), new Task(new Metadata('foo1', 'bar1'), 2, 'blah2')];

document.write(JSON.stringify({"Tasks": tasks, "__count": tasks.length}));

answered Mar 11, 2013 at 10:03

Srikanth Venugopalan

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Comments

Yoeri · Accepted Answer · 2013-03-11 10:07:16Z

Create objects with constructors and use the JSON api.

var jsonData = {};
jsonData.Tasks = new Array();

var Metadata = function(uri, type){
  this.uri = uri;
  this.type = type;
}

var Task = function (metadata, id, category){
  this.__metadata = metadata;
  this.ID = id;
  this.Category = category;
}

var tasks = jsonData.Tasks;

tasks.push(
  new Task(
    new Metadata("someUri", "someType"),
    1,
    "someCategory")
);

jsbin: working example

skurty · Accepted Answer · 2013-03-11 10:12:16Z

0

I'm using this code and it works :

var jsonData = {};
jsonData.Tasks = [];

var count = 0;

for(...) {
    jsonData.Tasks.push({
        "__metadata" : {
            "uri" : "...",
            "type" : "..."
        },
        "ID" : "...",
        "Category" : "...",
    });

    count++;
}

jsonData.__count = count;

Thank you for your answers and your reactivity !

answered Mar 11, 2013 at 10:12

skurty

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1 Comment

Yoeri Over a year ago

I still recommend you use objects rather than string literals. I don't know what it means performance whise, but is a lot less error prone.

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