Asp.Net 2.0的TreeView执行RenderControl方法时会出错？

SeeMyWorld 2007-02-05 12:22:48

请问有没有人会解决这个问题？

我的源代码如下：
System.Web.UI.WebControls.TreeView tree = new TreeView();
this.InitializePostNodes(tree.Nodes, table, (int)topic["tid"], topPostID);
System.IO.StringWriter writer = new System.IO.StringWriter();
tree.SkipLinkText = "";
tree.RenderControl(new HtmlTextWriter(writer));

错误信息如下：
Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 49: System.IO.StringWriter writer = new System.IO.StringWriter();
Line 50: tree.SkipLinkText = "";
Line 51: tree.RenderControl(new HtmlTextWriter(writer));
Line 52: this.Response.Write(writer);
Line 53:

Source File: h:\Websites\show.aspx Line: 51

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.UI.WebControls.TreeView.GetImageUrl(Int32 index) +5656
System.Web.UI.WebControls.TreeNode.Render(HtmlTextWriter writer, Int32 position, Boolean[] isLast, Boolean enabled) +2472
System.Web.UI.WebControls.TreeView.RenderContents(HtmlTextWriter writer) +487
System.Web.UI.WebControls.WebControl.Render(HtmlTextWriter writer) +29
System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +25
System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +121
System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +22
ASP.aspx_1_showforum_aspx.WriteTreeRow(DataRow topic) in h:\Websites\show.aspx:51
ASP.aspx_1_showforum_aspx.OnInit(EventArgs e) in h:\Websites\show.aspx:1043
System.Web.UI.Control.InitRecursive(Control namingContainer) +321
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +692

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悦铉 2011-09-08

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是，遇到同样问题了。很奇怪。把treeview换成 button就没事

ktv102 2011-08-30

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Object reference not set to an instance of an object

System.Web.UI.WebControls.TreeView tree = new TreeView();
this.InitializePostNodes(tree.Nodes, table, (int)topic[ "tid "], topPostID);
System.Text.StringBuilder sb = new System.Text.StringBuilder();
System.IO.StringWriter writer= new System.IO.StringWriter(sb);
tree.SkipLinkText = " ";
tree.RenderControl(new HtmlTextWriter(writer));

binbin2000 2007-06-06

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遇到同样问题了。

SeeMyWorld 2007-02-05

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这一行完全是调用System.Web.dll的

hertcloud 2007-02-05

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tree.RenderControl(new HtmlTextWriter(writer));
这一行有错?
你单步调试跟踪进去看看是那里出的错

SeeMyWorld 2007-02-05

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不是的，你可以试试执行这几行

System.Web.UI.WebControls.TreeView tree = new TreeView();

System.IO.StringWriter writer = new System.IO.StringWriter();

tree.RenderControl(new HtmlTextWriter(writer));