c# - ASP.NET TreeView：使用 TreeView.TreeNodePopulate 时无法获取 TreeNode.Parent 和 TreeNode.ChildNodes

Question

TreeView在用户第一次扩展父节点时，我正在填充控件的节点，如ASP.NET: How to Create an Expandable Empty TreeNode中所述，使用按需填充。填充过程运行良好。

问题是当我尝试获取TreeNode.Parentnull时，即使它TreeNode不是根节点。此外，即使指定的...TreeNode.ChildNodes有一些子节点，也会返回一个空集合。TreeNode

对此有解释吗？而且，我能做些什么来解决它？

谢谢你。

Answer 1

如果您的用户选择了根父节点，则下面的代码示例应该可以使用数据集合填充树：

protected void ParseTreeNodes（对象发送者，System.Web.UI.WebControls.TreeNodeEventArgs e）

{
    //Uncomment this line below and inspect the 'nodes' variable if you need to inspect all of the nodes
    //var nodes = this.MyTreeView.Nodes;

    //Some call to get data for example
    var dataCollection = GetSomeDataForTheTree()

    //Iterate through and create a new node for each row in the query results.
    //Notice that the query results are stored in the table of the DataSet.
    foreach (MyClassWithData data in dataCollection)
    {
        //Create the new node using the values from the collection:
        TreeNode newNode = new TreeNode(data.LastName, system.ID)
            {
                //Set the PopulateOnDemand property to false, because these are leaf nodes 
                and do not need to be populated on subsequent calls.
                PopulateOnDemand = false,
                SelectAction = TreeNodeSelectAction.Select
            };

        //Add the new node to the ChildNodes collection of the parent node.                    
        e.node.ChildNodes.Add(NewNode);
    }
}

如果您遇到父节点问题或知道Nodes集合中的特定值，我添加了额外的代码行来检查树视图中的当前节点。