Grouping  - AS3 Flex

The method used to compare items when sorting. If you specify this property, Flex ignores any compareFunction properties that you specify in the SortField objects that you use in this class.

The compare function must have the following signature:

         function [name](a:Object, b:Object, fields:Array=null):int

This function must return the following:

• -1, if a should appear before b in the sorted sequence.
• 0, if a equals b.
• 1, if a should appear after b in the sorted sequence.

To return to the internal comparison function, set this value to null.

The fields Array specifies the object fields to compare. Typically, the algorithm will compare properties until the field list is exhausted or a non-zero value can be returned. For example:

        function myCompare(a:Object, b:Object, fields:Array=null):int
        {
            var result:int = 0;
            var i:int = 0;
            var propList:Array = fields ? fields : internalPropList;
            var len:int = propList.length;
            var propName:String;
            while (result == 0 && (i < len))
            {
                propName = propList[i];
                result = compareValues(a[propName], b[propName]);
                i++;
            }
            return result;
        }
     
        function compareValues(a:Object, b:Object):int
        {
            if (a == null && b == null)
                return 0;
     
            if (a == null)
              return 1;
     
            if (b == null)
               return -1;
     
            if (a < b)
                return -1;
     
            if (a > b)
                return 1;
     
            return 0;
        }

The default value is an internal compare function that can perform a string, numeric, or date comparison in ascending or descending order, with case-sensitive or case-insensitive string comparisons. Specify your own function only if you need a custom comparison algorithm. This is normally only the case if a calculated field is used in a display.

Alternatively, you can specify separate compare functions for each sort field by using the SortField class compare property. This way you can use the default comparison for some fields and a custom comparison for others.

An Array of GroupingField objects that specifies the fields used to group the data. The order of the GroupingField objects in the Array determines field priority order when sorting.

The default value is null.

Related API Elements

A callback function to run on each group node to determine the grouping object. By default, a new Object will be created for group nodes.

You can supply a groupingObjectFunction that provides the appropriate Object for group nodes.

The method signature is:

      myGroupObjectFunction(label:String):Object

Where label contains the value that will be shown for that group node. The function returns an Object which will be used for group nodes.

      private function groupObjFunction(label:String):Object
      {
          var obj:Object = {};
          obj.name = "Bob";
     
          return obj;
      }
      

The name of the field added to the flat data to create the hierarchy. The value of the top nodes (nodes representing the group fields) in every group will be represented by this property. Use this property to specify a different name.

The default value is GroupLabel.

Constructor.