Asp.net TreeView动态加载节点（一）

1.TreeNode的PopulateOnDemand="True"后节点就是动态从后台加载的.

2.但是如果上层TreeView的EnableClientScript="false",就会导致页面Postback

3.TreeView的TreeNodePopulate是PopulateOnDemand="True"并且TreeNode内已有数据才触发的

4.TreeNode的Depth属性是指从根结点算起到现在节点的层数,根结点层数为0

5.TreeNode NewNode = new TreeNode(row["CategoryName"].ToString(),row["CategoryID"].ToString())的第一个参数设置了

TreeNode类的Value 属性值.这个属性值会在发生TreeNodePopulate()事件的TreeNode对像回传用到.sqlQuery.Parameters.Add

("@categoryid", SqlDbType.Int).Value =node.Value;

附代码:

一、HTML

1. <asp:SqlDataSource ID="SqlDataSource1" runat="server"
2. ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
3. SelectCommand="SELECT [CategoryID], [CategoryName] FROM [Categories]">
4. </asp:SqlDataSource>
5. <asp:TreeView ID="TreeView1" runat="server" MaxDataBindDepth="2"
6. ontreenodepopulate="TreeView1_TreeNodePopulate" EnableClientScript="true" ExpandDepth="0">
7. <Nodes>
8. <asp:TreeNode PopulateOnDemand="True" Text="产品列表" Value="产品列表"></asp:TreeNode>
9. </Nodes>
10. </asp:TreeView>

二、C#

1. protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
2. {
3. if (e.Node.ChildNodes.Count == 0)
4. {
5. switch (e.Node.Depth)
6. {
7. case 0:
8. PopulateCategories(e.Node);
9. break;
10. case 1:
11. PopulateProducts(e.Node);
12. break;
13. }
14. }
15. }
16. void PopulateCategories(TreeNode node)
17. {
18. SqlCommand sqlQuery = new SqlCommand(
19. "Select CategoryName, CategoryID From Categories");
20. DataSet resultSet;
21. resultSet = RunQuery(sqlQuery);
22. if (resultSet.Tables.Count > 0)
23. {
24. foreach (DataRow row in resultSet.Tables[0].Rows)
25. {
26. TreeNode NewNode = new
27. TreeNode(row["CategoryName"].ToString(),
28. row["CategoryID"].ToString());
29. NewNode.PopulateOnDemand = true;
30. NewNode.SelectAction = TreeNodeSelectAction.Expand;
31. node.ChildNodes.Add(NewNode);
32. }
33. }
34. }
35. void PopulateProducts(TreeNode node)
36. {
37. SqlCommand sqlQuery = new SqlCommand();
38. sqlQuery.CommandText = "Select ProductName From Products " +
39. " Where CategoryID = @categoryid";
40. sqlQuery.Parameters.Add("@categoryid", SqlDbType.Int).Value =
41. node.Value;
42. DataSet ResultSet = RunQuery(sqlQuery);
43. if (ResultSet.Tables.Count > 0)
44. {
45. foreach (DataRow row in ResultSet.Tables[0].Rows)
46. {
47. TreeNode NewNode = new
48. TreeNode(row["ProductName"].ToString());
49. NewNode.PopulateOnDemand = false;
50. NewNode.SelectAction = TreeNodeSelectAction.None;
51. node.ChildNodes.Add(NewNode);
52. }
53. }
54. }
55. private DataSet RunQuery(SqlCommand sqlQuery)
56. {
57. string connectionString =
58. ConfigurationManager.ConnectionStrings
59. ["NorthwindConnectionString"].ConnectionString;
60. SqlConnection DBConnection =
61. new SqlConnection(connectionString);
62. SqlDataAdapter dbAdapter = new SqlDataAdapter();
63. dbAdapter.SelectCommand = sqlQuery;
64. sqlQuery.Connection = DBConnection;
65. DataSet resultsDataSet = new DataSet();
66. try
67. {
68. dbAdapter.Fill(resultsDataSet);
69. }
70. catch
71. {
72. labelStatus.Text = "Unable to connect to SQL Server.";
73. }
74. return resultsDataSet;
75. }