Packagemx.collections
Interfacepublic interface ISort
Implementors Sort

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

The ISort interface defines the interface for classes that provide the sorting information required to sort the data of a collection view.

See also

mx.collections.ICollectionView
mx.collections.ISortField


Public Properties
 PropertyDefined By
  compareFunction : Function
The method used to compare items when sorting.
ISort
  fields : Array
An Array of ISortField objects that specifies the fields to compare.
ISort
  unique : Boolean
Indicates if the sort should be unique.
ISort
Public Methods
 MethodDefined By
  
findItem(items:Array, values:Object, mode:String, returnInsertionIndex:Boolean = false, compareFunction:Function = null):int
Finds the specified object within the specified array (or the insertion point if asked for), returning the index if found or -1 if not.
ISort
  
propertyAffectsSort(property:String):Boolean
Return whether the specified property is used to control the sort.
ISort
  
reverse():void
Goes through the fields array and calls reverse() on each of the ISortField objects in the array.
ISort
  
sort(items:Array):void
Apply the current sort to the specified array (not a copy).
ISort
Property Detail
compareFunctionproperty
compareFunction:Function

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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:

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.


Implementation
    public function get compareFunction():Function
    public function set compareFunction(value:Function):void
fieldsproperty 
fields:Array

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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.

The default value is null.


Implementation
    public function get fields():Array
    public function set fields(value:Array):void

See also

uniqueproperty 
unique:Boolean

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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.

The default value is false.


Implementation
    public function get unique():Boolean
    public function set unique(value:Boolean):void
Method Detail
findItem()method
public function findItem(items:Array, values:Object, mode:String, returnInsertionIndex:Boolean = false, compareFunction:Function = null):int

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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.

Parameters

items:Array — the Array within which to search.
 
values:Object — Object containing the properties to look for (or the object to search for, itself). The object must consist of field name/value pairs, where the field names are names of fields specified by the fields property, in the same order they are used in that property. You do not have to specify all of the fields from the fields property, but you cannot skip any in the order. Therefore, if the fields properity lists three fields, you can specify its first and second fields in this parameter, but you cannot specify only the first and third fields.
 
mode:String — String containing the type of find to perform. Valid values are:
ANY_INDEX_MODEReturn any position that is valid for the values.
FIRST_INDEX_MODEReturn the position where the first occurrance of the values is found.
LAST_INDEX_MODEReturn the position where the last ocurrance of the specified values is found.
 
returnInsertionIndex:Boolean (default = false) — If the method does not find an item identified by the values parameter, and this parameter is true the findItem() method returns the insertion point for the values, that is the point in the sorted order where you should insert the item.
 
compareFunction:Function (default = null) — a comparator function to use to find the item. If you do not specify this parameter or , or if you provide a null value, findItem() function uses the compare function determined by the ISort instance's compareFunction property, passing in the array of fields determined by the values object and the current SortFields. If you provide a non-null value, findItem() function uses it as the compare function. The signature of the function passed as compareFunction must be as follows: function myCompareFunction(a:Object, b:Object):int. Note that there is no third argument unlike the compare function for ISort.compareFunction() property.

Returns
int — int The index in the array of the found item. If the returnInsertionIndex parameter is false and the item is not found, returns -1. If the returnInsertionIndex parameter is true and the item is not found, returns the index of the point in the sorted array where the values would be inserted.

Throws
SortError — If there are any parameter errors, the find critieria is not compatible with the sort or the comparator function for the sort can not be determined.
propertyAffectsSort()method 
public function propertyAffectsSort(property:String):Boolean

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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.

Parameters

property:String — The name of the field to test.

Returns
Boolean — Whether the property value might affect the sort outcome. If the sort uses the default compareFunction, returns true if the property parameter specifies a sort field. If the sort or any ISortField uses a custom comparator, there's no way to know, so return true.
reverse()method 
public function reverse():void

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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.

Note: a future release of Apache Flex SDK will change the signature of this function to return a reversed clone of this Sort instance. See FLEX-34853.

sort()method 
public function sort(items:Array):void

Language Version : ActionScript 3.0
Product Version : Flex 4.5
Runtime Versions : Flash Player 9, AIR 1.1

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.

Parameters

items:Array — Array of items to sort.