![]() ![]() ![]() ![]() Thank you very much for taking the time to write this useful tutorial! When you run the code, the TreeView should appear as follows: This will cause the method to load all of its child nodes. The method call passes in the node’s Id and the node itself. It then calls itself, making the method recursive. The code then loops through those items and adds the nodes to the parent node. The filteredItems variable contains the results of a lambda expression finding all of the items in the list with the passed in parentId. The parentNode is the TreeView node under which the items are added. The code will find all items in the list with the defined parent Id. The parentId is the Id value associated with the parent node. The PopulateTreeView method has two parameters: parentId and parentNode. Private Sub PopulateTreeView(ByVal parentId As Integer, _ĭim filteredItems = treeViewList.Where(Function(item) _ Var filteredItems = treeViewList.Where(item =>įoreach (var i in filteredItems.ToList())ĬhildNode = (i.Text) Private void PopulateTreeView(int parentId, TreeNode parentNode) The PopulateTreeView method uses recursion to populate the TreeView from the list. It then calls the PopulateTreeView method (shown below). The Add method of the list sets the data into the list. This code defines a generic List that contains the set of TreeViewItem instances. TreeViewList.Add(New TreeViewItem() With ) Private treeViewList As New List(Of TreeViewItem) ParentID = 3, ID = 5, Text = "Child of second child node" }) ParentID = 3, ID = 4, Text = "Child of second child node" }) ParentID = 1, ID = 3, Text = "Second child node" }) ParentID = 1, ID = 2, Text = "First child node" }) ParentID = 0, ID = 1, Text = "Parent node" }) In the WinForm containing the TreeView control, add the code to build the list as shown below. It also has a Text property that contains the text of the TreeView node. The class defines an Id associated with the item and a ParentId defining the Id of the parent item (that is the item under which this item will appear in the TreeView). (In VS 2010, VB will have auto-implemented properties as well.) It is using Public fields instead of Public Properties as it should. The VB code is just me being lazy tonight. The C# code uses auto-implemented properties to short-cut the code. Then it demonstrates how to use recursion to populate the TreeView control from the list.įirst, create a class that will store the data for the TreeView. In the mean time, the workaround is to use the TreeView’s SelectedNode property instead.This post details first how to build a list containing the data to display in a WinForms TreeView control. I googled up this problem and I found that this bug was reported on Connect, and it will be fixed in the next version. Apparently, during the expand, if there are more child nodes that fit on the screen, the parent node scrolls to the top, but the cursor stays in the same place where the double click occurred. Notice where the cursor is – that’s the node that was passed in the event handler. And that helped me realize that the e.Node is actually the node that is currently under the mouse cursor!ĭouble clicking on Fonts makes the following happen: I placed a MessageBox.Show(e.Node.Text) in the NodeMouseDoubleClick handler. I made a small WinForms application with just a TreeView, and I filled it with the contents of my C:\Windows directory. I noticed that it was not the same node all the time – it was different. Since the sub-child nodes count was 0, the event handled the (incorrect) node. To my surprise, I discovered today that by double clicking on a collapsed parent node, the e.Node parameter was not the node I actually double clicked on, but one of the child nodes. Most of the time when we need something to happen when a child node is double clicked, but not the parent, we write something similar to: void NodeMouseDoubleClick( object sender, TreeNodeMouseClickEventArgs e) Usually, double clicking on a collapsed tree node (which obviously has child nodes) will expand it. Here’s a strange bug I’ve encountered today in a WinForms application.
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