Collection Sorting in Flex

Collection sorting is programmed using a Sort object and one or more SortField objects from the mx.collections package.

General steps for setting up collection sorting:

1. Create a Sort object
2. Create one or more SortField objects
3. Set the Sort/Fields on the Collection
4. Call the Collection's refresh() method

   collection.sort = new Sort();
   collection.sort.fields = [ new SortField(null); ];
   collection.refresh();

Sort Fields

Sort Fields are used by a Sort object to sort the items in the collection by one or more of each item's field. A SortField object encapsulates what field to sort by and how to sort it.

So each SortField added to a sort corresponds to a field of the collection items.

For instance, a sort field could specify to sort by items by the "firstName" field case-insensitively.

   // create a case-insensitive sort field
   var sortField1:SortField = new SortField( "firstName" );
   sortField1.caseInsensitive = true;

As another example, a sort field could specify to sort the "pageCount" field, a numeric value, in descending order.

   // create a numeric, descending sort field
   var sortField2:SortField = new SortField( "pageCount" );
   sortField2.numeric = true;
   sortField2.descending = true;

Sort fields are then applied to a Sort object as the fields property (array).

   var sort:Sort = new Sort();
   sort.fields = [ sortField1, sortField2 ];

   // create a sort field for simple item values (no field name)
   var sortField:SortField = new SortField( null );
   sortField1.descending = true;

Related Links:

• Collections