ASP. net c # generate the drop-down list tree implementation code

:

Code: Copy codeThe Code is as follows: using System. Data;
Using System. Web. UI. WebControls;
/// <Summary>
/// Generate a drop-down list tree based on the DataTable
/// </Summary>
Public class DropDownListHelp
{
Private string gridline;
Private DataTable dt;
Public DropDownListHelp ()
{
//
// TODO: add the constructor logic here
//
}
/// <Summary>
/// Generate a tree drop-down menu based on the Datatable
/// </Summary>
/// <Param name = "datatable"> </param>
/// <Param name = "parentKeyField"> keyword field of the parent node </param>
/// <Param name = "parentKey"> upper-level node value </param>
/// <Param name = "keyField"> key field of the current node </param>
/// <Param name = "sortString"> sort string </param>
/// <Param name = "ddl"> DownList </param>
Public void createDropDownTree (DataTable datatable, string parentKeyField, string parentKey, string keyField, string textField, string sortString, DropDownList ddl)
{
Dt = datatable;
Ddl. Items. Add (new ListItem ("",""));
AddChildItems (parentKeyField, parentKey, keyField, textField, sortString, ddl );
}
/// <Summary>
/// Recursive Tree node generation
/// </Summary>
/// <Param name = "parentKeyField"> keyword field of the parent node </param>
/// <Param name = "parentKey"> upper-level node value </param>
/// <Param name = "keyField"> key field of the current node </param>
/// <Param name = "sortString"> sort string </param>
/// <Param name = "ddl"> DownList Control </param>
/// <Returns> </returns>
Private void addChildItems (string parentKeyField, string parentKey, string keyField, string textField, string sortString, DropDownList ddl)
{
DataView dv = new DataView (dt, parentKeyField + "= '" + parentKey + "'", sortString, DataViewRowState. CurrentRows );
Int a = dv. Count;
If (dv. Count = 0)
{
Return;
}
For (int I = 0; I <a; I ++)
{
Gridline = "";
Dv. RowFilter = parentKeyField + "= '" + parentKey + "'";
Dv. Sort = sortString;
GetTreeLine (parentKeyField, dv [I] [parentKeyField]. ToString (), keyField, dv [I] [keyField]. ToString (), sortString );
Dv. RowFilter = parentKeyField + "= '" + parentKey + "'";
Dv. Sort = sortString;
Ddl. Items. Add (new ListItem (gridline + (I = a-1? "Outputs": "outputs") + dv [I] [textField]. ToString (), dv [I] [keyField]. ToString ()));
AddChildItems (parentKeyField, dv [I] [keyField]. ToString (), keyField, textField, sortString, ddl );
}
Dv. Dispose ();
}
/// <Summary>
/// Trace the connection line of the Spanning Tree
/// </Summary>
/// <Param name = "parentKeyField"> keyword field of the parent node </param>
/// <Param name = "parentKey"> upper-level node value </param>
/// <Param name = "keyField"> key field of the current node </param>
/// <Param name = "nodeKey"> current node value </param>
/// <Param name = "sortString"> sort string </param>
/// <Returns> </returns>
Private void getTreeLine (string parentKeyField, string parentKey, string keyField, string nodeKey, string sortString)
{
// Select the parent node
DataView dv = new DataView (dt, keyField + "= '" + parentKey + "'", sortString, DataViewRowState. CurrentRows );
If (dv. Count> 0)
{
// Select the parent node at the same level
Dv. RowFilter = parentKeyField + "= '" + dv [0] [parentKeyField]. ToString () + "'";
Dv. Sort = sortString;
For (int j = 0; j <dv. Count; j ++)
{
If (dv [j] [keyField]. ToString () = parentKey)
{
If (j = dv. Count-1)
{
Gridline = "" + gridline;
}
Else
{
Gridline = "finished" + gridline;
}
}
}
GetTreeLine (parentKeyField, dv [0] [parentKeyField]. ToString (), keyField, dv [0] [keyField]. ToString (), sortString );
}
Dv. Dispose ();
}
}

Call:Copy codeThe Code is as follows: DropDownListHelp ddlHelper = new DropDownListHelp ();
DdlHelper. createDropDownTree (dt, "parentID", "1", "ID", "Text", "Text asc", DropDownList1 );