Interface ICollectionView

ICollectionView is an interface that applications writing their own collections can implement to enable current record management, sorting, filtering, grouping etc in a custom way.

Inherited Members

System.Collections.IEnumerable.GetEnumerator()

System.Collections.Specialized.INotifyCollectionChanged.CollectionChanged

Namespace: System.ComponentModel

Assembly: OpenSilver.dll

Syntax

public interface ICollectionView : IEnumerable, INotifyCollectionChanged

Properties

CanFilter

Indicates whether or not this ICollectionView can do any filtering.

Declaration

bool CanFilter { get; }

Property Value

Type	Description
System.Boolean

CanGroup

Returns true if this view really supports grouping. When this returns false, the rest of the interface is ignored.

Declaration

bool CanGroup { get; }

Property Value

Type	Description
System.Boolean

CanSort

Whether or not this ICollectionView does any sorting.

Declaration

bool CanSort { get; }

Property Value

Type	Description
System.Boolean

Culture

Culture contains the CultureInfo used in any operations of the ICollectionView that may differ by Culture, such as sorting.

Declaration

CultureInfo Culture { get; set; }

Property Value

Type	Description
System.Globalization.CultureInfo

CurrentItem

Return current item.

Declaration

object CurrentItem { get; }

Property Value

Type	Description
System.Object

CurrentPosition

The ordinal position of the CurrentItem within the (optionally sorted and filtered) view.

Declaration

int CurrentPosition { get; }

Property Value

Type	Description
System.Int32

Filter

Filter is a callback set by the consumer of the ICollectionView and used by the implementation of the ICollectionView to determine if an item is suitable for inclusion in the view.

Declaration

Predicate<object> Filter { get; set; }

Property Value

Type	Description
System.Predicate<System.Object>

GroupDescriptions

The description of grouping, indexed by level.

Declaration

ObservableCollection<GroupDescription> GroupDescriptions { get; }

Property Value

Type	Description
System.Collections.ObjectModel.ObservableCollection<GroupDescription>

Groups

The top-level groups, constructed according to the descriptions given in GroupDescriptions.

Declaration

ReadOnlyObservableCollection<object> Groups { get; }

Property Value

Type	Description
System.Collections.ObjectModel.ReadOnlyObservableCollection<System.Object>

IsCurrentAfterLast

Return true if CurrentItem is beyond the end (End-Of-File).

Declaration

bool IsCurrentAfterLast { get; }

Property Value

Type	Description
System.Boolean

IsCurrentBeforeFirst

Return true if CurrentItem is before the beginning (Beginning-Of-File).

Declaration

bool IsCurrentBeforeFirst { get; }

Property Value

Type	Description
System.Boolean

IsEmpty

Returns true if the resulting (filtered) view is emtpy.

Declaration

bool IsEmpty { get; }

Property Value

Type	Description
System.Boolean

SortDescriptions

Collection of Sort criteria to sort items in this view over the SourceCollection.

Declaration

SortDescriptionCollection SortDescriptions { get; }

Property Value

Type	Description
SortDescriptionCollection

Remarks

Simpler implementations do not support sorting and will return an empty and immutable / read-only SortDescription collection. Attempting to modify such a collection will cause NotSupportedException. Use CanSort property on CollectionView to test if sorting is supported before modifying the returned collection.

One or more sort criteria in form of SortDescription can be added, each specifying a property and direction to sort by.

SourceCollection

SourceCollection is the original un-filtered collection of which this ICollectionView is a view.

Declaration

IEnumerable SourceCollection { get; }

Property Value

Type	Description
System.Collections.IEnumerable

Methods

Contains(Object)

Return true if the item belongs to this view. No assumptions are made about the item. This method will behave similarly to IList.Contains(). If the caller knows that the item belongs to the underlying collection, it is more efficient to call Filter.

Declaration

bool Contains(object item)

Parameters

Type	Name	Description
System.Object	item

Returns

Type	Description
System.Boolean

DeferRefresh()

Enter a Defer Cycle. Defer cycles are used to coalesce changes to the ICollectionView.

Declaration

IDisposable DeferRefresh()

Returns

Type	Description
System.IDisposable

MoveCurrentTo(Object)

Move CurrentItem to the given item.

Declaration

bool MoveCurrentTo(object item)

Parameters

Type	Name	Description
System.Object	item	Move CurrentItem to this item.

Returns

Type	Description
System.Boolean	true if CurrentItem points to an item within the view.

MoveCurrentToFirst()

Move CurrentItem to the first item.

Declaration

bool MoveCurrentToFirst()

Returns

Type	Description
System.Boolean	true if CurrentItem points to an item within the view.

MoveCurrentToLast()

Move CurrentItem to the last item.

Declaration

bool MoveCurrentToLast()

Returns

Type	Description
System.Boolean	true if CurrentItem points to an item within the view.

MoveCurrentToNext()

Move CurrentItem to the next item.

Declaration

bool MoveCurrentToNext()

Returns

Type	Description
System.Boolean	true if CurrentItem points to an item within the view.

MoveCurrentToPosition(Int32)

Move CurrentItem to the item at the given index.

Declaration

bool MoveCurrentToPosition(int position)

Parameters

Type	Name	Description
System.Int32	position	Move CurrentItem to this index

Returns

Type	Description
System.Boolean	true if CurrentItem points to an item within the view.

MoveCurrentToPrevious()

Move CurrentItem to the previous item.

Declaration

bool MoveCurrentToPrevious()

Returns

Type	Description
System.Boolean	true if CurrentItem points to an item within the view.

Refresh()

Re-create the view, using any SortDescriptions.

Declaration

void Refresh()

Events

CurrentChanged

Raise this event after changing to a new current item.

Declaration

event EventHandler CurrentChanged

Event Type

Type	Description
System.EventHandler

CurrentChanging

Raise this event before change of current item pointer. Handlers can cancel the change.

Declaration

event CurrentChangingEventHandler CurrentChanging

Event Type

Type	Description
CurrentChangingEventHandler

Remarks

Classes implementing ICollectionView should use the following pattern:

Raise the CurrentChanging event before any change of currency and check the return value before proceeding and raising CurrentChanged event:

     void MoveCurrentToNext()
     {
         CurrentChangingEventArgs args = new CurrentChangingEventArgs();
         OnCurrentChanging(args);
         if (!args.Cancel)
         {
             // ... update private data structures ...
             CurrentChanged();
         }
     }