asp.net 2.0中TREEVIEW中動態增加結點
2024-07-10 12:56:42
供稿：網友
菜鳥學堂：
在asp.net 2.0中，要動態從數據庫中取出內容，動態增加結點，其實不難，比如以sql server 2000的pubs數據庫為例子，要以樹型列表方式，取出作者，做為根結點，然后取出每位作者寫過什么書，作為子結點，可以這樣
<%@ page language="c#"%>
<%@ import namespace="system.data"%>
<%@ import namespace="system.data.sqlclient"%>
<%@ import namespace="system.configuration"%>
<!doctype htmlpublic"-//w3c//dtd xhtml 1.1//en""http://www.w3.org/tr/xhtml11/dtd/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>dynamic population of the treeview control</title>
<script runat=server>
void node_populate(object sender,
system.web.ui.webcontrols.treenodeeventargs e)
{
if(e.node.childnodes.count == 0)
{
switch( e.node.depth )
{
case 0:
fillauthors(e.node);
break;
case 1:
filltitlesforauthors(e.node);
break;
}
}
}
void fillauthors(treenode node)
{
string connstring = system.configuration.configurationsettings.
connectionstrings["northwindconnnection"].connectionstring;
sqlconnection connection = new sqlconnection(connstring);
sqlcommand command = new sqlcommand("select * from
authors",connection);
sqldataadapter adapter = new sqldataadapter(command);
dataset authors = new dataset();
adapter.fill(authors);
if (authors.tables.count > 0)
{
foreach (datarow row in authors.tables[0].rows)
{
treenode newnode = new
treenode(row["au_fname"].tostring() + " " +
row["au_lname"].tostring(),
row["au_id"].tostring());
newnode.populateondemand = true;
newnode.selectaction = treenodeselectaction.expand;
node.childnodes.add(newnode);
}
}
}
void filltitlesforauthors(treenode node)
{
string authorid = node.value;
string connstring = system.configuration.configurationsettings.
connectionstrings["northwindconnnection"].connectionstring;
sqlconnection connection = new sqlconnection(connstring);
sqlcommand command = new sqlcommand("select t.title,
t.title_id from titles t" +
" inner join titleauthor ta on
t.title_id = ta.title_id " +
" where ta.au_id = '" + authorid + "'", connection);
sqldataadapter adapter = new sqldataadapter(command);
dataset titlesforauthors = new dataset();
adapter.fill(titlesforauthors);
if (titlesforauthors.tables.count > 0)
{
foreach (datarow row in titlesforauthors.tables[0].rows)
{
treenode newnode = new treenode(
row["title"].tostring(), row["title_id"].tostring());
newnode.populateondemand = false;
newnode.selectaction = treenodeselectaction.none;
node.childnodes.add(newnode);
}
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:treeviewrunat="server" expandimageurl="images/closed.gif"
collapseimageurl="images/open.gif"
ontreenodepopulate="node_populate" id="tvwauthors">
<nodes>
<asp:treenodetext="authors" populateondemand=true
value="0"/>
</nodes>
</asp:treeview>
</div>
</form>
</body>
</html>
其中，注意ontreenodepopulate事件，是在展開樹的結點時發生的，這里定義了自定義的node_populate,在node_populate中，檢查當前結點的深度，如果是0，就是根結點，于是就調用fillauthors過程，取出所有的作者，如果深度是1，則是葉子結點，調用filltitlesforauthors過程。其中，要注意它們中的動態建立樹結點的過程，如：
treenode newnode = new treenode(row["au_fname"].tostring() + " " +
row["au_lname"].tostring(),
row["au_id"].tostring());
newnode.populateondemand = true;
newnode.selectaction = treenodeselectaction.expand;
node.childnodes.add(newnode);
其中， popluateondemand屬性表明，該結點會動態擴展。
