Packagemx.collections
Classpublic class Sort
InheritanceSort Inheritance flash.events.EventDispatcher
Implements ISort
Subclasses Sort

Language Version : ActionScript 3.0
Product Version : Flex 3
Runtime Versions : Flash Player 9, AIR 1.1


Starting with Flex 4.5, Apache recommends that you use the spark.collections.Sort class as an alternative to this class.

Provides the sorting information required to establish a sort on an existing view (ICollectionView interface or class that implements the interface). After you assign a Sort instance to the view's sort property, you must call the view's refresh() method to apply the sort criteria.

Typically the sort is defined for collections of complex items, that is collections in which the sort is performed on one or more properties of the objects in the collection. The following example shows this use:

                  
     var col:ICollectionView = new ArrayCollection();
     // In the real world, the collection would have more than one item.
     col.addItem({first:"Anders", last:"Dickerson"});
      // Create the Sort instance.
     var sort:ISort = new Sort();
      // Set the sort field; sort on the last name first, first name second.
     // Both fields are case-insensitive.
     sort.fields = [new SortField("last",true), new SortField("first",true)];
       // Assign the Sort object to the view.
     col.sort = sort;
      // Apply the sort to the collection.
     col.refresh();
  
               

There are situations in which the collection contains simple items, like String, Date, Boolean, etc. In this case, apply the sort to the simple type directly. When constructing a sort for simple items, use a single sort field, and specify a null name (first) parameter in the SortField object constructor. For example:

                     
     var col:ICollectionView = new ArrayCollection();
     col.addItem("California");
     col.addItem("Arizona");
     var sort:Sort = new Sort();
      // There is only one sort field, so use a null
     // first parameter.
     sort.fields = [new SortField(null, true)];
     col.sort = sort;
     col.refresh();
  
                  

The Flex implementations of the ICollectionView interface retrieve all items from a remote location before executing a sort. If you use paging with a sorted list, apply the sort to the remote collection before you retrieve the data.

By default this Sort class does not provide correct language specific sorting for strings. For this type of sorting please see the spark.collections.Sort and spark.collections.SortField classes.

Note: to prevent problems like FLEX-34853 it is recommended to use SortField instances as immutable objects (by not changing their state).

MXML SyntaxexpandedHide MXML Syntax

The <mx:Sort> tag has the following attributes:

  <mx:Sort
  Properties
  compareFunction="Internal compare function"
  fields="null"
  unique="false | true"
  />
  

In case items have inconsistent data types or items have complex data types, the use of the default built-in compare functions is not recommended. Inconsistent sorting results may occur in such cases. To avoid such problem, provide a custom compare function and/or make the item types consistent.

Just like any other AdvancedStyleClient-based classes, the Sort and SortField classes do not have a parent-child relationship in terms of event handling. Locale changes in a Sort instance are not dispatched to its SortField instances automatically. The only exceptional case is the internal default SortField instance used when no explicit fields are provided. In this case, the internal default SortField instance follows the locale style that the owner Sort instance has.

Default MXML Propertyfields

See also

mx.collections.ICollectionView
ISortField
spark.collections.Sort
spark.collections.SortField


Public Properties
 PropertyDefined By
  compareFunction : Function
The method used to compare items when sorting.
Sort
  fields : Array
An Array of ISortField objects that specifies the fields to compare.
Sort
  unique : Boolean
Indicates if the sort should be unique.
Sort
Public Methods
 MethodDefined By
  
Sort(fields:Array = null, customCompareFunction:Function = null, unique:Boolean = false)
Constructor.
Sort
  
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.
Sort
  
propertyAffectsSort(property:String):Boolean
Return whether the specified property is used to control the sort.
Sort
  
reverse():void
Goes through the fields array and calls reverse() on each of the ISortField objects in the array.
Sort
  
sort(items:Array):void
Apply the current sort to the specified array (not a copy).
Sort
Protected Methods
 MethodDefined By
  
Sort
Public Constants
 ConstantDefined By
  ANY_INDEX_MODE : String = any
[static] When executing a find return the index any matching item.
Sort
  FIRST_INDEX_MODE : String = first
[static] When executing a find return the index for the first matching item.
Sort
  LAST_INDEX_MODE : String = last
[static] When executing a find return the index for the last matching item.
Sort
Property Detail
compareFunctionproperty
compareFunction:Function

Language Version : ActionScript 3.0
Product Version : Flex 3
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 3
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.

This property can be used as the source for data binding.


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 3
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
Constructor Detail
Sort()Constructor
public function Sort(fields:Array = null, customCompareFunction:Function = null, unique:Boolean = false)

Language Version : ActionScript 3.0
Product Version : Flex 3
Runtime Versions : Flash Player 9, AIR 1.1

Constructor.

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

Parameters
fields:Array (default = null) — An Array of ISortField objects that specifies the fields to compare.
 
customCompareFunction:Function (default = null) — Use a custom function to compare the objects in the collection to which this sort will be applied.
 
unique:Boolean (default = false) — Indicates if the sort should be unique.
Method Detail
createEmptySortField()method
protected function createEmptySortField():ISortField

Returns
ISortField
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 3
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.
propertyAffectsSort()method 
public function propertyAffectsSort(property:String):Boolean

Language Version : ActionScript 3.0
Product Version : Flex 3
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 3
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 3
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.

Constant Detail
ANY_INDEX_MODEConstant
public static const ANY_INDEX_MODE:String = any

Language Version : ActionScript 3.0
Product Version : Flex 3
Runtime Versions : Flash Player 9, AIR 1.1

When executing a find return the index any matching item.

FIRST_INDEX_MODEConstant 
public static const FIRST_INDEX_MODE:String = first

Language Version : ActionScript 3.0
Product Version : Flex 3
Runtime Versions : Flash Player 9, AIR 1.1

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

LAST_INDEX_MODEConstant 
public static const LAST_INDEX_MODE:String = last

Language Version : ActionScript 3.0
Product Version : Flex 3
Runtime Versions : Flash Player 9, AIR 1.1

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