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POWindows Forms VB.NET - Populate TreeView with Hierarchical data
 

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  1. POWindows Forms VB.NET - Populate TreeView with Hierarchical data
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    <p>Aloha, I'm trying to populate a treeview on a windows form app with Hierarchical data from a SQL db.</p> <p>The structure from the database is:</p> <pre><code>id_def id_parent description 1 NULL Multidificiência 2 NULL Síndrome 3 NULL Outros 4 1 Surdez de Transmissão 5 2 Surdez Neurossensorial Ligeira 6 3 Surdez Neurossensorial Média </code></pre> <p>the records with NULL value at id_parent, are the main categories, and the ones with their id_parent, are sub categories.</p> <p>Can anyone help with the code to populate the TreeView ? I managed to do it with an ASP.NET app, if it helps, here's the code:</p> <pre><code>protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) PopulateRootLevel(); } private void PopulateRootLevel() { SqlConnection objConn = new SqlConnection("Data Source=1.1.1.1;Initial Catalog=DREER_EDUCANDOS2006;User ID=sre_web;Password=xxx"); SqlCommand objCommand = new SqlCommand("select id_deficiencia,descricao,(select count(*) FROM NecessidadesEspeciais WHERE id_deficiencia_pai=sc.id_deficiencia) childnodecount FROM NecessidadesEspeciais sc where id_deficiencia_pai IS NULL", objConn); SqlDataAdapter da = new SqlDataAdapter(objCommand); DataTable dt = new DataTable(); da.Fill(dt); PopulateNodes(dt, TreeView1.Nodes); } private void PopulateSubLevel(int parentid, TreeNode parentNode) { SqlConnection objConn = new SqlConnection("Data Source=1.1.1.1;Initial Catalog=DREER_EDUCANDOS2006;User ID=sre_web;Password=xxx"); SqlCommand objCommand = new SqlCommand("select id_deficiencia,descricao,(select count(*) FROM NecessidadesEspeciais WHERE id_deficiencia_pai=sc.id_deficiencia) childnodecount FROM NecessidadesEspeciais sc where id_deficiencia_pai=@id_deficiencia_pai", objConn); objCommand.Parameters.Add("@id_deficiencia_pai", 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["descricao"].ToString(); tn.Value = dr["id_deficiencia"].ToString(); nodes.Add(tn); //If node has child nodes, then enable on-demand populating tn.PopulateOnDemand = ((int)(dr["childnodecount"]) &gt; 0); } } </code></pre>
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    1. USpelican_george
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    1. CONote sure exactly what your problem is. Is it something like this you are looking for (populating a winforms treeview "on demand", C# example though): http://stackoverflow.com/questions/1851729/treeview-child-node-populating-problem/1851789#1851789
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      1. USFredrik Mörk
    2. COTack för ditt svar fredrik =) if u take a look here: http://aspalliance.com/732_Display_Hierarchical_Data_with_TreeView_in_ASPNET_20 that's exactly what I pretend, but for windows form.
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      1. USpelican_george
    3. CO@Rui: I'm impressed :) Briefly checked the article; it looks like my answer to that other question should do the trick for you. It converts to VB.NET rather well using this converter: http://www.developerfusion.com/tools/convert/csharp-to-vb/ The only thing that does not quite work out is the multi-line lambda inside the QueueUserWorkItem, but I guess that could be extracted to a separate method to solve the problem.
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