Data Binding Overview
RadPanelBar supports binding to various types of data sources:
-
ASP 2.0 DataSource types including
To bind the panel to a data source, specify the data source as the value of the DataSource property and call the DataBind method. If you are using declarative data sources such as AccessDataSource or SiteMapDataSource, use the DataSourceID property instead of the DataSource property.
Usually, you also want to do one or more of the following:
Set Text, Value or NavigateUrl properties using:
DataTextField - specifies the field of the data source that provides the Text of the panel items. If this field does not contain string values, you can use the DataTextFormatString property to ensure that field values are formatted the way you want.
DataValueField - Specifies the field of the data source that provides the Value of the panel items
DataNavigateUrlField - Specifies the field of the data source that provides the NavigateUrl of the panel items.
If the data source is not hierarchical, you can establish the hierarchy through an ID to ParentID relationship using:
DataFieldID - The name of the field in the data source that acts as a key, uniquely identifying rows.
DataFieldParentID - The name of the field in the data source that identifies the key field value of the parent item. The value of this field for root items should be null(table- or object-based data source) or the default value of the corresponding value type used (object-based data source).
If the data source contains fields that map to other properties of panel items or to custom attributes, use the ItemDataBound event to set those values:
As an alternative to using the ItemDataBound event handler, you can use DataBindings to declaratively map fields from the data source to properties of panel items. The DataBindings collection also lets you map fields differently, based on the level of items.
protected void RadPanelBar1_ItemDataBound(object sender, RadPanelBarEventArgs e)
{
e.Item.ToolTip = "Read more about " + (string)DataBinder.Eval(e.Item.DataItem, "Text");
}
Protected Sub RadPanelBar1_ItemDataBound(ByVal sender As Object, ByVal e As RadPanelBarEventArgs)
e.Item.ToolTip = "Read more about " + DirectCast(DataBinder.Eval(e.Item.DataItem, "Text"), String)
End Sub
Hierarchical data
Typically, panels are hierarchical in structure. That is, they contain child panel items that are accessed through parent panel items. RadPanelBar reconstructs this hierarchy differently, depending on the type of data source:
-
For inherently hierarchical data sources, RadPanelBar will automatically create the panel item hierarchy. Such data sources include
- XmlDataSource
- SiteMapDataSource
-
For table-structured data sources, RadPanelBar uses the ID to ParentID relationship to establish a hierarchy. Such data sources include
- DataSet, DataTable, and DataView
- SqlDataSource
- AccessDataSource
-
For object-based data sources, RadPanelBar uses the ID to ParentID relationship to establish a hierarchy. Such data sources include
- ObjectDataSource
- LinqDataSource
- Any class that implements the IEnumerable interface such as List, Array, ArrayList, etc.
Appending Data Bound Items
RadPanelBar exposes the AppendDataBoundItems property (False by default). If you bind the panel using the DataBind method, all panel items are automatically cleared.
Setting AppendDataBoundItems to True preserves the items that are already present in the panel. This lets you bind RadPanelBar to multiple data sources or use both unbound and bound modes.
Binding depth
RadPanelBar exposes the MaxDataBindDepth property. This property is used to determine the binding depth. If for example you want to bind only the first two levels of the panel bar, you should set this property to 2. The default value of the MaxDataBindDepth property is -1, which means that all items will be bound. Marking the panel bar instance with MaxDataBindDepth="0" will NOT bind any items.
Using Templates with Data-bound Items
You can use templates with a data-bound panel. To bind template items to column values, use DataBinder.Eval expressions in the template's definition:
<%# DataBinder.Eval(Container.DataItem, "ColumnName") %>
Note that you use Container.DataItem to access the panel item when it is in a bound mode. The panel item must already be bound before template binding can work.