Sort  - 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 ISortField 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 value:

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

To return to the internal comparision 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. Specify your own function only if you need a 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 ISortField class compareFunction property; This way you can use the default comparison for some fields and a custom comparison for others.

An Array of ISortField objects that specifies the fields to compare. The order of the ISortField objects in the array determines field priority order when sorting. The default sort comparator checks the sort fields in array order until it determinines a sort order for the two fields being compared.

Il valore predefinito è null.

Questa proprietà può essere utilizzata come origine per l’associazione di dati. Quando questa proprietà viene modificata, invia l’evento fieldsChanged .

Elementi API correlati

Indicates if the sort should be unique. Unique sorts fail if any value or combined value specified by the fields listed in the fields property result in an indeterminate or non-unique sort order; that is, if two or more items have identical sort field values. An error is thrown if the sort is not unique. The sorting logic uses this unique property value only if sort field(s) are specified explicitly. If no sort fields are specified explicitly, no error is thrown even when there are identical value elements.

Il valore predefinito è false.

Constructor.

Creates a new Sort with no fields set and no custom comparator.

Finds the specified object within the specified array (or the insertion point if asked for), returning the index if found or -1 if not. The ListCollectionView class findxxx() methods use this method to find the requested item; as a general rule, it is easier to use these functions, and not findItem() to find data in ListCollectionView-based objects. You call the findItem() method directly when writing a class that supports sorting, such as a new ICollectionView implementation. The input items array need to be sorted before calling this function. Otherwise this function will not be able to find the specified value properly.

Parametri

Return whether the specified property is used to control the sort. The function cannot determine a definitive answer if the sort uses a custom comparator; it always returns true in this case.

Parametri

Goes through the fields array and calls reverse() on each of the ISortField objects in the array. If the field was descending now it is ascending, and vice versa.

Note: an ICollectionView does not automatically update when the objects in the fields array are modified; call its refresh() method to update the view.

Apply the current sort to the specified array (not a copy). To prevent the array from being modified, create a copy use the copy in the items parameter.

Flex ICollectionView implementations call the sort method automatically and ensure that the sort is performed on a copy of the underlying data.

Parametri

When executing a find return the index any matching item.

When executing a find return the index for the first matching item.

When executing a find return the index for the last matching item.