To check if an object is empty or not

Question

Hi friends, I want to check in my function if a passed argument of type object is empty or not. Sometimes it is empty but still not null thus I can not rely on null condition. Is there some property like 'length'/'size' for flex objects which I can use here. Please help. Thanks in advance.

Answer 1

If you mean if an Object has no properties:

var isEmpty:Boolean = true;
for (var n in obj) { isEmpty = false; break; }

Answer 2

This is some serious hack but you can use:

Object.prototype.isEmpty = function():Boolean {
    for(var i in this)
     if(i != "isEmpty")
      return false
    return true
}

var p = {};
trace(p.isEmpty()); // true
var p2 = {a:1}
trace(p2.isEmpty()); // false

Answer 3

Depends on what your object is, or rather what you expect it to have. For example if your object is supposed to contain some property called name that you are looking for, you might do

if(objSomeItem == null || objSomeItem.name == null || objSomeItem.name.length == 0)
{
 trace("object is empty");
}

or if your object is actually supposed to be something else, like an array you could do

var arySomeItems = objSomeItem as Array;
if(objSomeItem == null || arySomeItems == null || arySomeItems.length == 0)
{
  trace("object is empty");
}

You could also use other ways through reflection, such as ObjectUtil.getClassInfo, then enumerate through the properties to check for set values.... this class help:

import flash.utils.describeType;
import flash.utils.getDefinitionByName;

public class ReflectionUtils 
{
 /** Returns an Array of All Properties of the supplied object */
 public static function GetVariableNames(objItem:Object):Array
 {
  var xmlPropsList:XMLList = describeType(objItem)..variable;
  var aryVariables:Array = new Array();
  if (xmlPropsList != null)
  {
   for (var i:int; i < xmlPropsList.length(); i++)
   {
    aryVariables.push(xmlPropsList[i].@name);
   }
  }

  return aryVariables;
 }

 /** Returns the Strongly Typed class of the specified library item */
 public static function GetClassByName($sLinkageName:String):Class
 {
  var tObject:Class = getDefinitionByName($sLinkageName) as Class;
  return tObject;
 }

 /** Constructs an instance of the speicified library item */
 public static function ConstructClassByName($sLinkageName:String):Object
 {
  var tObject:Class = GetClassByName($sLinkageName);
  //trace("Found Class: " + tMCDefinition);
  var objItem:* = new tObject();
  return objItem;
 }

 public static function DumpObject(sItemName:String, objItem:Object):void
 {
  trace("*********** Object Dump: " + sItemName + " ***************");
  for (var sKey:String in objItem)
  {
   trace("    " + sKey +": " + objItem[sKey]);
  }
 }
 //}
}

Another thing to note is you can use a simple for loop to check through an objects properties, thats what this dumpobject function is doing.

Answer 4

can use use the hasProperty method to check for length

var i:int = myObject.hasProperty("length") ? myObject.length: 0;

Answer 5

You can also try:

ObjectUtil.getClassInfo(obj).properties.length > 0

The good thing about it is that getClassInfo gives you much more info about the object, eg. you get the names of all the properties in the object, which might come in handy.