HierarchicalDataBoundControl.GetData(String) Method
Definition
Important
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Retrieves a HierarchicalDataSourceView object that the data-bound control uses to perform data operations.
protected:
virtual System::Web::UI::HierarchicalDataSourceView ^ GetData(System::String ^ viewPath);
protected virtual System.Web.UI.HierarchicalDataSourceView GetData (string viewPath);
abstract member GetData : string -> System.Web.UI.HierarchicalDataSourceView
override this.GetData : string -> System.Web.UI.HierarchicalDataSourceView
Protected Overridable Function GetData (viewPath As String) As HierarchicalDataSourceView
Parameters
- viewPath
- String
The hierarchical path of the view to retrieve.
Returns
The HierarchicalDataSourceView object that the data-bound control uses to perform data operations.
Exceptions
A HierarchicalDataSourceView could not be retrieved for the specified viewPath
.
Examples
The following code example demonstrates how the GetData method is called to retrieve the HierarchicalDataSourceView object from the associated data source control and how the HierarchicalDataSourceView.Select method is called to retrieve the data. This code example is part of a larger example provided for the HierarchicalDataBoundControl class.
protected override void PerformDataBinding() {
base.PerformDataBinding();
// Do not attempt to bind data if there is no
// data source set.
if (!IsBoundUsingDataSourceID && (DataSource == null)) {
return;
}
HierarchicalDataSourceView view = GetData(RootNode.DataPath);
if (view == null) {
throw new InvalidOperationException
("No view returned by data source control.");
}
IHierarchicalEnumerable enumerable = view.Select();
if (enumerable != null) {
Nodes.Clear();
try {
RecurseDataBindInternal(RootNode, enumerable, 1);
}
finally {
}
}
}
private void RecurseDataBindInternal(TreeNode node,
IHierarchicalEnumerable enumerable, int depth) {
foreach(object item in enumerable) {
IHierarchyData data = enumerable.GetHierarchyData(item);
if (null != data) {
// Create an object that represents the bound data
// to the control.
TreeNode newNode = new TreeNode();
RootViewNode rvnode = new RootViewNode();
rvnode.Node = newNode;
rvnode.Depth = depth;
// The dataItem is not just a string, but potentially
// an XML node or some other container.
// If DataTextField is set, use it to determine which
// field to render. Otherwise, use the first field.
if (DataTextField.Length > 0) {
newNode.Text = DataBinder.GetPropertyValue
(data, DataTextField, null);
}
else {
PropertyDescriptorCollection props =
TypeDescriptor.GetProperties(data);
// Set the "default" value of the node.
newNode.Text = String.Empty;
// Set the true data-bound value of the TextBox,
// if possible.
if (props.Count >= 1) {
if (null != props[0].GetValue(data)) {
newNode.Text =
props[0].GetValue(data).ToString();
}
}
}
Nodes.Add(rvnode);
if (data.HasChildren) {
IHierarchicalEnumerable newEnumerable =
data.GetChildren();
if (newEnumerable != null) {
RecurseDataBindInternal(newNode,
newEnumerable, depth+1 );
}
}
if ( _maxDepth < depth) _maxDepth = depth;
}
}
}
Protected Overrides Sub PerformDataBinding()
MyBase.PerformDataBinding()
' Do not attempt to bind data if there is no
' data source set.
If Not IsBoundUsingDataSourceID AndAlso DataSource Is Nothing Then
Return
End If
Dim view As HierarchicalDataSourceView = GetData(RootNode.DataPath)
If view Is Nothing Then
Throw New InvalidOperationException _
("No view returned by data source control.")
End If
Dim enumerable As IHierarchicalEnumerable = view.Select()
If Not (enumerable Is Nothing) Then
Nodes.Clear()
Try
RecurseDataBindInternal(RootNode, enumerable, 1)
Finally
End Try
End If
End Sub
Private Sub RecurseDataBindInternal(ByVal node As TreeNode, _
ByVal enumerable As IHierarchicalEnumerable, _
ByVal depth As Integer)
Dim item As Object
For Each item In enumerable
Dim data As IHierarchyData = enumerable.GetHierarchyData(item)
If Not data Is Nothing Then
' Create an object that represents the bound data
' to the control.
Dim newNode As New TreeNode()
Dim rvnode As New RootViewNode()
rvnode.Node = newNode
rvnode.Depth = depth
' The dataItem is not just a string, but potentially
' an XML node or some other container.
' If DataTextField is set, use it to determine which
' field to render. Otherwise, use the first field.
If DataTextField.Length > 0 Then
newNode.Text = DataBinder.GetPropertyValue _
(data, DataTextField, Nothing)
Else
Dim props As PropertyDescriptorCollection = _
TypeDescriptor.GetProperties(data)
' Set the "default" value of the node.
newNode.Text = String.Empty
' Set the true data-bound value of the TextBox,
' if possible.
If props.Count >= 1 Then
If Not props(0).GetValue(data) Is Nothing Then
newNode.Text = props(0).GetValue(data).ToString()
End If
End If
End If
Nodes.Add(rvnode)
If data.HasChildren Then
Dim newEnumerable As IHierarchicalEnumerable = _
data.GetChildren()
If Not (newEnumerable Is Nothing) Then
RecurseDataBindInternal(newNode, _
newEnumerable, depth + 1)
End If
End If
If MaxDepth < depth Then
MaxDepth = depth
End If
End If
Next item
End Sub
Remarks
The GetData method retrieves a HierarchicalDataSourceView object from the associated data source control by calling the GetDataSource method.
Applies to
See also
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