Problem with enumerators in JSON

[TWM73]

I have a problem with generic style adding. I created a collection of objects in JSON that correspond to the style definition.

var myDef = {
   "mtPanelName": "superScript",
   "inddType": "Character",
   "parametersOfAddition": {
   "name": "Sup",
   "position": "Position.SUPERSCRIPT"
   }
app.activeDocument.characterStyles.add(myDef.parametersOfAddition);

But in JSON I can save the enumerator name only as a String. Unfortunately, most methods do not allow the use of a String. The problem generally concerns the storage of object names in JSON. I meet him more often. How can I solve it?

Regards,

Tomek

[grefel · Accepted solution]

Behind Position.SUPERSCRIPT is acutally a Number (in this case 1935831907) InDesign ExtendScript API (14.0) . Use this in your JSON. Simply omit the "

   "position": Position.SUPERSCRIPT

[Marc Autret]

Hi colleagues,

The important word in Gregor's answer is “behind”, as he writes, “Behind Position.SUPERSCRIPT is actually a Number (…)”

Indeed, keep in mind that although Position.SUPERSCRIPT can easily coerce into a Number, this is actually not a Number in CS5 and later. In fact, that's an object of the class Enumerator.

  // The truth 'behind' enumerator instances
  // ---
  alert( typeof Position.SUPERSCRIPT );       // => object
  alert( Position.SUPERSCRIPT.__class__ );    // => Enumerator
  alert( Position.SUPERSCRIPT.toString() );   // => "SUPERSCRIPT"
  alert( +Position.SUPERSCRIPT );             // => 1936749411

As you can see, a quick way to retrieve the underlying number of any enumeraor, myEnum, is to use the shortcut +myEnum (which implicitly involves the .valueOf() method.)

• More detail on this topic can be found in IdExtenso's enum extension.

The reason I emphasize this point here is, an Enumerator instance shouldn't appear as such in a JSON stream. Better is to numerify it (+myEnum) if no better option is available, because you can later assign that number to any DOM attribute that expects such enumerator and this will work fine. By contrast, if you assign the string reflection—i.e, myEnum.toString()—this won't work. In your JSON stream, there is good chance that the object Position.SUPERCRIPT will mutely translates into its associated string at some point and without your knowledge due to implicit stringification…

• $$.JSON automatically coerces Enumerator instances into numbers. If you make it verbose, it provides graceful hints on the origin of that number:

// One of the advantages of using $$.JSON in InDesign
// ---
var obj = { myAttribute: Position.SUPERSCRIPT };
alert( $$.JSON(obj, 1/*verbose*/) );
// Output (stringified)
//----------------------
{
    "myAttribute" : 0x73707363 /* [spsc] */
}

Hope that helps.

@+

Marc

[grefel]

Thanks for the clarification Marc

[Loic.Aigon]

Now I know why you put those "+" everywhere

[Marc Autret]

Yep

Storing a number is not the same as storing an Object reference.

@+

Marc

[TWM73]

Thank you very much! That's what I was looking for.

Regards,

Tomek