ASPxTreeList.BeforeHeaderFilterFillItems Event
Allows you to populate the header filter dropdown with custom items instead of default items.
Namespace: DevExpress.Web.ASPxTreeList
Assembly: DevExpress.Web.ASPxTreeList.v24.1.dll
NuGet Package: DevExpress.Web
Declaration
public event ASPxTreeListBeforeHeaderFilterFillItemsEventHandler BeforeHeaderFilterFillItemsEvent Data
The BeforeHeaderFilterFillItems event's data class is ASPxTreeListBeforeHeaderFilterFillItemsEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| Column | Gets the data column currently being filtered. |
| Handled | Specifies whether the BeforeHeaderFilterFillItems event is handled. Inherited from ASPxGridBeforeHeaderFilterFillItemsEventArgs. |
| Values | Gets a collection that contains the header filer values. Inherited from ASPxGridHeaderFilterEventArgs. |
The event data class exposes the following methods:
| Method | Description |
|---|---|
| AddShowAll() | Adds the ‘All’ item to the header filter. Inherited from ASPxGridHeaderFilterEventArgs. |
| AddShowBlanks(String) | Creates and adds the “Blanks” filter value to the header filter values. Inherited from ASPxGridHeaderFilterEventArgs. |
| AddShowNonBlanks(String) | Creates and adds the “(Non blanks)” filter value to the header filter values. Inherited from ASPxGridHeaderFilterEventArgs. |
| AddValue(String, CriteriaOperator) | Adds a new filter item with the specified filter criteria operator to the header filter. Inherited from ASPxGridBeforeHeaderFilterFillItemsEventArgs. |
| AddValue(String, String, String) | Adds a new filter item with the specified filter criteria to the header filter. Inherited from ASPxGridHeaderFilterEventArgs. |
| AddValue(String, String) | Adds a new filter item to the header filter. Inherited from ASPxGridHeaderFilterEventArgs. |
| CreateShowBlanksValue(String) | Creates and returns the (Blanks) filter item used to filter a column by blank values. Inherited from ASPxGridHeaderFilterEventArgs. |
| CreateShowNonBlanksValue(String) | Creates and returns the (Non blanks) filter item used to filter a column by blank values. Inherited from ASPxGridHeaderFilterEventArgs. |
Remarks
The header filter allows users to filter column data. When a user clicks on the filter button, the tree list displays a filter dropdown. The BeforeHeaderFilterFillItems event fires before the filter dropdown is shown and default filter items are created. The event allows you to create custom filter items.
Set the Handled property to true to prevent the HeaderFilterFillItems event from being raised. Otherwise, the event clears the item collection before filling it with default items.
Use the HeaderFilterFillItems event to add custom items to the default items.