我有一个数据库表（名为Topics），其中包含以下字段：
并使用它们我想在c＃中填充TreeView。我怎么能这样做？
提前致谢...
答案 0 :(得分：13)
可能会是这样的。如果您需要更多，请详细说明您想要做什么。
//In Page load
foreach (DataRow row in topics.Rows)
{
TreeNode node = new TreeNode(dr["name"], dr["topicId"])
node.PopulateOnDemand = true;
TreeView1.Nodes.Add(node);
}
///
protected void PopulateNode(Object sender, TreeNodeEventArgs e)
{
string topicId = e.Node.Value;
//select from topic where parentId = topicId.
foreach (DataRow row in topics.Rows)
{
TreeNode node = new TreeNode(dr["name"], dr["topicId"])
node.PopulateOnDemand = true;
e.Node.ChildNodes.Add(node);
}
}
答案 1 :(得分：7)
不完全。
树木通常不会一次性加载所有东西，因此处理得最好。因此，您需要获取没有parentID的根节点（或主题）。然后将它们添加到树根节点，然后为添加的每个节点添加其子节点。
foreach (DataRow row in topicsWithOutParents.Rows)
{
TreeNode node = New TreeNode(... whatever);
DataSet childNodes = GetRowsWhereParentIDEquals(row["topicId"]);
foreach (DataRow child in childNodes.Rows)
{
Treenode childNode = new TreeNode(..Whatever);
node.Nodes.add(childNode);
}
Tree.Nodes.Add(node);
}
答案 2 :(得分：6)
这段代码对我来说非常合适，看看它我认为它会对你有所帮助:)。
protected void Page_Load(object sender, EventArgs e)
{
DataSet ds = RunQuery("Select topicid,name from Topics where Parent_ID IS NULL");
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
TreeNode root = new TreeNode(ds.Tables[0].Rows[i][1].ToString(),ds.Tables[0].Rows[i][0].ToString());
root.SelectAction = TreeNodeSelectAction.Expand;
CreateNode(root);
TreeView1.Nodes.Add(root);
}
}
void CreateNode(TreeNode node)
{
DataSet ds = RunQuery("Select topicid, name from Category where Parent_ID =" + node.Value);
if (ds.Tables[0].Rows.Count == 0)
{
return;
}
for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
{
TreeNode tnode = new TreeNode(ds.Tables[0].Rows[i][1].ToString(), ds.Tables[0].Rows[i][0].ToString());
tnode.SelectAction = TreeNodeSelectAction.Expand;
node.ChildNodes.Add(tnode);
CreateNode(tnode);
}
}
DataSet RunQuery(String Query)
{
DataSet ds = new DataSet();
String connStr = "???";//write your connection string here;
using (SqlConnection conn = new SqlConnection(connStr))
{
SqlCommand objCommand = new SqlCommand(Query, conn);
SqlDataAdapter da = new SqlDataAdapter(objCommand);
da.Fill(ds);
da.Dispose();
}
return ds;
}
答案 3 :(得分：6)
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
PopulateRootLevel();
}
private void PopulateRootLevel()
{
SqlConnection objConn = new SqlConnection(connStr);
SqlCommand objCommand = new SqlCommand(@"select FoodCategoryID,FoodCategoryName,(select count(*) FROM FoodCategories WHERE ParentID=c.FoodCategoryID) childnodecount FROM FoodCategories c where ParentID IS NULL", objConn);
SqlDataAdapter da = new SqlDataAdapter(objCommand);
DataTable dt = new DataTable();
da.Fill(dt);
PopulateNodes(dt, TreeView2.Nodes);
}
private void PopulateSubLevel(int parentid, TreeNode parentNode)
{
SqlConnection objConn = new SqlConnection(connStr);
SqlCommand objCommand = new SqlCommand(@"select FoodCategoryID,FoodCategoryName,(select count(*) FROM FoodCategories WHERE ParentID=sc.FoodCategoryID) childnodecount FROM FoodCategories sc where ParentID=@parentID", objConn);
objCommand.Parameters.Add("@parentID", SqlDbType.Int).Value = parentid;
SqlDataAdapter da = new SqlDataAdapter(objCommand);
DataTable dt = new DataTable();
da.Fill(dt);
PopulateNodes(dt, parentNode.ChildNodes);
}
protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
{
PopulateSubLevel(Int32.Parse(e.Node.Value), e.Node);
}
private void PopulateNodes(DataTable dt, TreeNodeCollection nodes)
{
foreach (DataRow dr in dt.Rows)
{
TreeNode tn = new TreeNode();
tn.Text = dr["FoodCategoryName"].ToString();
tn.Value = dr["FoodCategoryID"].ToString();
nodes.Add(tn);
//If node has child nodes, then enable on-demand populating
tn.PopulateOnDemand = ((int)(dr["childnodecount"]) > 0);
}
}
答案 4 :(得分：5)
当没有大量数据时，连接数据库，获取数据并一次又一次地为子/子节点添加到树视图节点是不好的。它可以一次完成。见以下样本：
http://urenjoy.blogspot.com/2009/08/display-hierarchical-data-with-treeview.html
答案 5 :(得分：1)
这段代码非常适合我。认为这对于希望在树状视图中显示层次结构数据的人可能有用。到目前为止，我想这是最简单的。请检查一下，并投票是否有帮助。
参考：https://techbrij.com/display-hierarchical-data-with-treeview-in-asp-net
C＃代码：
//dtTree should be accessible in both page load and AddNodes()
//DocsMenu is the treeview Id
DataTable dtTree = new DataTable();
//declare your connection string
protected void Page_Load(object sender, EventArgs e)
{
//DataTable dtTree = new DataTable();
using (con)
{
con.Open();
string sQuery = "Select topicId,parentid,name from tbl_topicMaster";
SqlCommand cmd = new SqlCommand(sQuery, con);
cmd.CommandType = CommandType.Text;
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dtTree);
da.Dispose();
con.Close();
}
AddNodes(-1, DocsMenu.Nodes);
}
void AddNodes(int id, TreeNodeCollection tn)
{
foreach (DataRow dr in dtTree.Select("parentid= " + id))
{
TreeNode sub = new TreeNode(dr["name"].ToString(), dr["topicId"].ToString());
tn.Add(sub);
AddNodes(Convert.ToInt32(sub.Value), sub.ChildNodes);
}
}
aspx代码：
<asp:TreeView ID="DocsMenu" runat="server" ImageSet="BulletedList"
NodeIndent="15" >
<HoverNodeStyle Font-Underline="True" ForeColor="#6666AA" />
<NodeStyle Font-Names="Tahoma" Font-Size="8pt" ForeColor="Black" HorizontalPadding="2px"
NodeSpacing="0px" VerticalPadding="2px"></NodeStyle>
<ParentNodeStyle Font-Bold="False" />
<SelectedNodeStyle BackColor="#B5B5B5" Font-Underline="False" HorizontalPadding="0px"
VerticalPadding="0px" />
</asp:TreeView>