Custom object to JSON then back to a custom object?

Question

I've seen very similar questions to this, but I can't quite decide if they was answered clearly - maybe I'm being a bit dense, sorry. I want to have the convenience (and clarity) of my own object, call it a `CardboardBox()`. It won't contain code, just data. I want to write this to a database and read it back later, but obviously, it is a type `Object()` when it's read back. All I can think of to find out what it used to be is: - Have a member variable `type` that I set to CARDBOARD_BOX - Instantiate a new `CarbardBox()` and use a function (in the box) to copy the properties of `Object()` to the new `CardboardBox()` object Is there a better way of doing this? I'm pretty sure I can change the actual type. ``` function CardboardBox() { this.type = "CARDBOARD_BOX" this.name = "No set"; this.populate = new function(obj) { // populate this object with obj properties } var box = new CarboardBox(); // CarboardBox box.name = "My Box"; send = JSON.stringyfy(box); . . . obj = JSON.parse(send);…

Accepted Answer

One possible solution is the following:

```
function CardboardBox(n) {
  if(typeof(n) == 'string') {
    //build from name string
    this.name = n;
  } else {
    //build from object
    this.name = n.name;
  }

//add in this object's "type" in a place
  //that is unlikely to exist in other JSON strings
  this.__type = 'CardboardBox';
}

var box = new CardboardBox("My Box");
send = JSON.stringify(box), // JSON CarboardBox()
obj = JSON.parse(send, function(key, val) {
  //if this is an object, and is CardboardBox
  if(typeof(val) === 'object' && val.__type === 'CardboardBox')
      return new CardboardBox(val);

return val;

//or if your object is in a context (like window), and there are many of
  //them that could be in there, you can do:
  //
  //if(typeof(val) === 'object' && context[val.__type])
  //    return new context[val.__type](val);
});

console.log(obj);
```

Basically store the object type in a place you know to look for later on when parsing the json. if you have multiple objects you can instantiate in a single scope the second parse method may be more appropriate. This also will account for objects in the JSON that are not `CarboardBox`s.

Edit Here is a jsFiddle of this method in action.

Custom object to JSON then back to a custom object?

Solution

Problem