Sql Windows窗体VB.NET-使用分层数据填充TreeView
阿罗哈, 我正在尝试使用SQL db中的分层数据填充windows窗体应用程序上的树视图 数据库的结构为:Sql Windows窗体VB.NET-使用分层数据填充TreeView,sql,vb.net,treeview,hierarchical-data,Sql,Vb.net,Treeview,Hierarchical Data,阿罗哈, 我正在尝试使用SQL db中的分层数据填充windows窗体应用程序上的树视图 数据库的结构为: 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
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
id_父级为空的记录是主类别,id_父级为空的记录是子类别
有人能帮助编写代码来填充树视图吗?
我设法用ASP.NET应用程序实现了这一点,如果有帮助,下面是代码:
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"]) > 0);
}
}
取一个表,其中包含一些层次结构数据:
Id Name ParentNodeId
1 Top-level node 1 -1
2 A first-level child 1
3 Another top-level node -1
4 Another first-level child 1
5 First-level child in another branch 3
6 A second-level child 2
我重新编写了中的示例代码,以使用上表动态填充树视图(假设该表位于SQL server数据库中)。代码示例有点长
using System.Windows.Forms;
using System.Threading;
using System.Collections.Generic;
using System.Data.SqlClient;
public class TreeViewSample : Form
{
private TreeView _treeView;
public TreeViewSample()
{
this._treeView = new System.Windows.Forms.TreeView();
this._treeView.Location = new System.Drawing.Point(12, 12);
this._treeView.Size = new System.Drawing.Size(200, 400);
this._treeView.AfterExpand +=
new TreeViewEventHandler(TreeView_AfterExpand);
this.ClientSize = new System.Drawing.Size(224, 424);
this.Controls.Add(this._treeView);
this.Text = "TreeView Lazy Load Sample";
PopulateChildren(null);
}
void TreeView_AfterExpand(object sender, TreeViewEventArgs e)
{
if (e.Node.Nodes.Count == 1 && e.Node.Nodes[0].Tag == "dummy")
{
PopulateChildren(e.Node);
}
}
private void PopulateChildren(TreeNode parent)
{
// this node has not yet been populated, launch a thread
// to get the data
int? parentId = parent != null ? (parent.Tag as DataNode).Id : (int?)null;
ThreadPool.QueueUserWorkItem(state =>
{
IEnumerable<DataNode> childItems = GetNodes(parentId);
// load the data into the tree view (on the UI thread)
_treeView.BeginInvoke((MethodInvoker)delegate
{
PopulateChildren(parent, childItems);
});
});
}
private void PopulateChildren(TreeNode parent, IEnumerable<DataNode> childItems)
{
TreeNodeCollection nodes = parent != null ? parent.Nodes : _treeView.Nodes;
TreeNode child;
TreeNode dummy;
TreeNode originalDummyItem = parent != null ? parent.Nodes[0] : null;
foreach (var item in childItems)
{
child = new TreeNode(item.Text);
child.Tag = item;
dummy = new TreeNode("Loading. Please wait...");
dummy.Tag = "dummy";
child.Nodes.Add(dummy);
nodes.Add(child);
}
if (originalDummyItem != null)
{
originalDummyItem.Remove();
}
}
private IEnumerable<DataNode> GetNodes(int? parentId)
{
List<DataNode> result = new List<DataNode>();
using (SqlConnection conn = new SqlConnection(@"[your connection string]"))
using (SqlCommand cmd = new SqlCommand("select * from Nodes where ParentNodeId = @parentNodeId", conn))
{
cmd.Parameters.Add(new SqlParameter("@parentNodeId", System.Data.SqlDbType.Int));
cmd.Parameters["@parentNodeId"].Value = parentId != null ? parentId : -1;
conn.Open();
using (SqlDataReader reader = cmd.ExecuteReader())
{
int nodeIdCol = reader.GetOrdinal("NodeId");
int nameCol = reader.GetOrdinal("Name");
int parentIdCl = reader.GetOrdinal("ParentNodeId");
while (reader.Read())
{
result.Add(new DataNode
{
Id = reader.GetInt32(nodeIdCol),
Text = reader.GetString(nameCol),
ParentId = reader.IsDBNull(parentIdCl) ? (int?)null : reader.GetInt32(parentIdCl)
});
}
}
}
return result;
}
}
public class DataNode
{
public int Id { get; set; }
public string Text { get; set; }
public int? ParentId { get; set; }
}
使用System.Windows.Forms;
使用系统线程;
使用System.Collections.Generic;
使用System.Data.SqlClient;
公共类TreeViewSample:表单
{
私人树景(private TreeView);
公共TreeViewSample()
{
这._treeView=new System.Windows.Forms.treeView();
此._treeView.Location=新系统.图纸.点(12,12);
此._treeView.Size=新系统图尺寸(200400);
这个._treeView.AfterExpand+=
新的TreeviewVenthandler(TreeView_AfterExpand);
this.ClientSize=新系统.Drawing.Size(224424);
this.Controls.Add(this.\u treeView);
this.Text=“TreeView Lazy Load Sample”;
PopulateChildren(空);
}
void TreeView_AfterExpand(对象发送方,treevieventargs e)
{
if(e.Node.Nodes.Count==1&&e.Node.Nodes[0]。标记==“dummy”)
{
普及儿童(e.Node);
}
}
私有无效PopulateChildren(TreeNode父级)
{
//此节点尚未填充,请启动一个线程
//获取数据
int?parentId=parent!=null?(parent.Tag作为DataNode)。Id:(int?)null;
ThreadPool.QueueUserWorkItem(状态=>
{
IEnumerable childItems=GetNodes(parentId);
//将数据加载到树视图中(在UI线程上)
_BeginInvoke((MethodInvoker)委托
{
PopulateChildren(父项、子项);
});
});
}
私有void PopulateChildren(TreeNode父项、IEnumerable子项)
{
TreeNodeCollection节点=父节点!=null?父节点:_treeView.nodes;
树状幼体;
树形假人;
TreeNode originalDummyItem=parent!=null?parent.Nodes[0]:null;
foreach(childItems中的变量项)
{
child=新树节点(item.Text);
Tag=item;
dummy=新树节点(“正在加载,请稍候…”);
dummy.Tag=“dummy”;
添加(虚拟);
添加(子节点);
}
if(originalDummyItem!=null)
{
originalDummyItem.Remove();
}
}
私有IEnumerable GetNodes(int?parentId)
{
列表结果=新列表();
使用(SqlConnection conn=newsqlconnection(@“[您的连接字符串]”))
使用(SqlCommand cmd=newsqlcommand(“从ParentNodeId=@ParentNodeId,conn)的节点中选择*)
{
Add(新的SqlParameter(“@parentNodeId”,System.Data.SqlDbType.Int));
cmd.Parameters[“@parentNodeId”].Value=parentId!=null?parentId:-1;
conn.Open();
使用(SqlDataReader=cmd.ExecuteReader())
{
int nodeIdCol=reader.GetOrdinal(“NodeId”);
int nameCol=reader.GetOrdinal(“名称”);
int parentIdCl=reader.GetOrdinal(“ParentNodeId”);
while(reader.Read())
{
添加(新的数据节点)
{
Id=reader.GetInt32(nodeIdCol),
Text=reader.GetString(nameCol),
ParentId=reader.IsDBNull(parentIdCl)?(int?)null:reader.GetInt32(parentIdCl)
});
}
}
}
返回结果;
}
}
公共类数据节点
{
公共int Id{get;set;}
公共字符串文本{get;set;}
public int?ParentId{get;set;}
}
通过使用Linq to SQL,数据获取代码可能会变得更漂亮一些,但我希望它尽可能完整,所以我决定省去它以减少代码量。。。(这需要包含一些生成的Linq到SQL类)。请确切地注意您的问题所在。你是不是在寻找这样的东西(在winforms treeview“随需应变”中填充一个C#示例):Tack för ditt svar fredrik=)如果你看一下这里:这正是我假装的,但对于windows窗体。@Rui:我印象深刻:)简要地检查了这篇文章;看来我对另一个问题的回答应该对你有帮助。使用此转换器,它可以很好地转换为VB.NET:唯一不太有效的是QueueUserWorkItem中的多行lambda,但我想可以将其提取到一个单独的方法来解决问题。我的女朋友是瑞典人=)如果我能解决它,我会告诉你,谢谢你的帮助。cheers@Rui:无论如何,这与asp.net和c有关,与vb.net无关。谢谢你,这正是我所需要的。它100%有效。再次感谢您花时间为我编写代码。Fredrik,我还有一个问题:子节点总是使用创建虚拟节点时附带的标记“TreeViewSample.DataNode”填充。如何将标记与Id关联?我不确定我是否说清楚了,只需添加一个按钮:MessageBox.Show(treeView1.SelectedNode.Text.ToString()+treeView1.SelectedNode.Tag.ToString())@Rui:虚拟节点仅将字符串
“dummy”
分配给标记
属性。“真实”节点具有它们在中表示的DataNode