IHierarchyData.HasChildren Property

Definition

Namespace:

System.Web.UI

Assembly:

System.Web.dll

Indicates whether the hierarchical data node that the IHierarchyData object represents has any child nodes.

C#

public bool HasChildren { get; }

Property Value

Boolean

true if the current node has child nodes; otherwise, false.

Examples

The following code example demonstrates how an ASP.NET hierarchical data-bound control uses an IHierarchyData object in a recursive data-binding method. The items in an IHierarchicalEnumerable collection are enumerated, and for each an IHierarchyData object is retrieved using the GetHierarchyData method. Finally, the HasChildren property is checked to determine whether to recurse. This code example is part of a larger example provided for the HierarchicalDataBoundControl class.

C#

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;
        }
    }
}

Remarks

The HasChildren property is a convenience property that enables callers to avoid checking the return value of the GetChildren method for null. If the HasChildren property returns true, call the GetChildren method to retrieve an IHierarchicalEnumerable collection of child nodes.

Applies to

See also

• GetChildren()