I
had last week an ASP .net TreeView control to fill from a self-join table. I
looked on the Internet to find an Algorithm but I did not find any solution
using C# or VB .Net but a solution in Code Project using SQL or other using DataSets. I then
decided to post the following Algorithm that might help somebody
else.
Here is the table I used in the example and the generated treeview
image on the right.
|
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Here
is the code I used to generate the treeview:
<%@ Assembly Name="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral,
PublicKeyToken=71e9bce111e9429c" %>
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<%@ Import Namespace="Microsoft.SharePoint" %>
<%@ Import Namespace="System.Collections.Generic"
%>
<form runat="server">
</form>
<script runat="server">
public
class Location
{
private string
_locationName;
private int
_locationId;
private int
_parentLocationId;
public string
LocationName
{
get {
return
_locationName; }
set {
_locationName = value; }
}
public int
LocationId
{
get {
return _locationId;
}
set {
_locationId = value;
}
}
public int
ParentLocationId
{
get {
return
_parentLocationId; }
set {
_parentLocationId = value; }
}
}
//list of all nodes
SortedList<int, Location> myLocations =
new SortedList<int, Location>();
//list of all created nodes
SortedList<int, TreeNode> myCreatedNodes =
new SortedList<int, TreeNode>();
public
void
Page_Load(object
sender, EventArgs
e)
{
string result="<br>start loading page : " +
DateTime.Now.Second + " " + DateTime.Now.Millisecond;
try
{
System.Data.SqlClient.SqlConnection myCon =
new
System.Data.SqlClient.SqlConnection("Server=localhost;Database=myCompany;integrated
security=SSPI");
myCon.Open();
SqlCommand
myCommand = new
SqlCommand();
myCommand.CommandText = @"select ID,
Name,
ParentID
from
Location
";
myCommand.Connection = myCon;
SqlDataReader myReader =
myCommand.ExecuteReader();
while
(myReader.Read())
{
myLocation = new Location();
myLocation.LocationName = Convert.ToString(myReader[1]);
myLocation.LocationId = Convert.ToInt32(myReader[0]);
myLocations.Add(myLocation.LocationId,
myLocation);
TreeNode
aNode = null;
result+="<br>start processing
treeview : " + DateTime.Now.Second +
" " +
DateTime.Now.Millisecond;
foreach
(int aKey
in
myLocations.Keys)
{
string code =
myLocations[aKey].LocationId.ToString();
aNode = new
TreeNode(myLocations[aKey].LocationName,
code);
CreateNode(aNode);
}
result += "<br>end processing
treeview : " + DateTime.Now.Second +
" " +
DateTime.Now.Millisecond;
}
catch (Exception
ex)
{
Response.Write("error<BR>" +
ex.Message);
Response.Write("Trace<BR>" +
ex.StackTrace);
}
Response.Write(result);
}
public
void
CreateNode(TreeNode aNode)
{
//This list stores all the nodes id from the current node
to the ultimate parent
List<int> myPath = new List<int>();
if
(!myCreatedNodes.ContainsValue(aNode))//if the
node was not alreazdy created
{
int
nodeId=1001;
nodeId = Convert.ToInt32(aNode.Value);
//Building the current node path untill
the ultimate parent
myPath.Add(nodeId);
while (nodeId
!= 0)
{
if(nodeId!=0){
nodeId=
myLocations[nodeId].ParentLocationId;
myPath.Add(nodeId);
}
}
}
//descending from Ultimate parent until the
node
//if the current node does not exists we create it and add
it to created nodes collection.
//if it has not a parent we add it to the
treeview
//if it has a parent,the parent was already created because
we come from it, so we add the current node to the
parent.
TreeNode nodeToAdd =
null,
ParentNodeTofind = null;
for (int j = myPath.Count - 1; j >
-1; j--)
{
if (myPath[j]
!= 0)
{
//checking for each path if the nodes
was already created
if
(!myCreatedNodes.Keys.Contains(myLocations[myPath[j]].LocationId))
{
//creating the node and adding it to
the created nodes collection.
nodeToAdd = new TreeNode(myLocations[myPath[j]].LocationName,
myLocations[myPath[j]].LocationId.ToString());
myCreatedNodes.Add(myLocations[myPath[j]].LocationId,
nodeToAdd);
int parentId
= myLocations[myPath[j]].ParentLocationId;
//checking if the node has a parent
if (parentId
== 0)//this node has no parent we add it to
the tree view
{
TreeView1.Nodes.Add(nodeToAdd);
}
else//this node has a parent
{
//rerieving parent node (sure to find
it)
ParentNodeTofind =
myCreatedNodes[myLocations[myPath[j]].ParentLocationId];
//we add the node to its parent
childNodes
ParentNodeTofind.ChildNodes.Add(nodeToAdd);
}
}
}
}
}
</script>
