RadMenu dynamic databinding doesnt show

Question

I'm using SQL server 2012, and VS2013. I want to design a dynamic Radmenu(Telerik) which databind with sql server. But it doesnt show at runtime, and no error occured.

Here is the code.

     <telerik:RadScriptManager runat="server" ></telerik:RadScriptManager>
        <telerik:RadMenu ID="RadMenu1" runat="server" style="top: 0px; left: 0px; width: 800px;height:auto"
             Skin="Metro">
        </telerik:RadMenu>

code-behind

   protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            myCnn = new SqlConnection(myCnnstring);
            myCnn.Open();
            mysql = "select * from SYS_Menu";
            mycmd = new SqlCommand(mysql, myCnn);
            myda = new SqlDataAdapter(mycmd);
            myds = new DataSet();
            myda.Fill(myds);
            mydt = new DataTable();
            mydt = myds.Tables[0];

            RadMenu1.DataSource = mydt;
            RadMenu1.DataFieldID = "PK_ID";
            RadMenu1.DataFieldParentID = "ParentID";
            //Set Text, Value, and NavigateUrl:    
            RadMenu1.DataTextField = "TextField";
            RadMenu1.DataValueField = "PK_ID";
            RadMenu1.DataNavigateUrlField = "URL";
            RadMenu1.MaxDataBindDepth = -1;
            RadMenu1.DataBind();
            myCnn.Close();
        } 
    }

Table Sys_menu

PK_ID|ParentID|TextField|ValueField|URL
1|1|Home|Home|~/NewVersion/test2.aspx
10|9|SingleBuilding|SingleBuilding|~/NewVersion/test2.aspx
11|9|GroupBuilding|GroupBuilding|~/NewVersion/test2.aspx
2|1|Land|Land|~/NewVersion/test2.aspx
3|2|LandBlock|LandBlock|~/NewVersion/test2.aspx
4|2|LandCost|LandCost|~/NewVersion/test2.aspx
5|3|Voucher|Voucher|~/NewVersion/test2.aspx
6|3|Query|Query|~/NewVersion/test2.aspx
7|4|Voucher|Voucher|~/NewVersion/test2.aspx
8|4|Query|Query|~/NewVersion/test2.aspx
9|1|BuildingInfo|BuildingInfo|~/NewVersion/test2.aspx

another problem: I read the instruction of Telerik that the root of ParentID of hierarchical item should be null, but it will cause an error.

what should I do ? Thanks in advance.

Answer 1

make ParentID column value of root element is null.

1|1|Home|Home|~/NewVersion/test2.aspx

Answer 2

It is probably due to the parent nodes not having NULL in their ParentId column.

Can you modify the data (setting the nulls) before you bind the menu to it?