更新FormView asp.net中的问题。

Question

我已经通过查询字符串向本页发送了值。之后，我无法在modechanging事件上获取编辑模式。当我点击编辑按钮时，它只是回传而没有任何反应。如果点击编辑第二次它给出错误：

(Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request. For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.) 

请告诉我我错在哪里。

源代码 -

<asp:FormView ID="formview1" runat="server" AllowPaging="true" Caption="FireBrigade" DataKeyNames="FireBrigadeID" OnModeChanging="formview1_ModeChanging" 
     OnPageIndexChanging="formview1_PageIndexChanging"> 
     <ItemTemplate> 
      FireBrigade ID :<asp:Label ID="lblFID" runat="server" Text='<%# Eval("FireBrigadeID") %>'></asp:Label><br /> 
      Name :<asp:Label ID="Label3" runat="server" Text='<%# Eval("FBName") %>'></asp:Label><br /> 
      LatLong:<asp:Label ID="Label1" runat="server" Text='<%# Eval("LatLng") %>'></asp:Label><br /> 
      Address: <asp:Label ID="Label2" runat="server" Text='<%# Eval("Address") %>'></asp:Label><br /> 
      Contact: <asp:Label ID="Label4" runat="server" Text='<%# Eval("ContactNumber") %>'></asp:Label><br /> 
      <asp:LinkButton ID="EditButton" Text="Edit" CommandName="Edit" RunAt="server"/> 
     </ItemTemplate> 
     <EditItemTemplate> 
      FireBrigade ID :<asp:TextBox ID="txtFID" runat="server" Text='<%# Bind("FireBrigadeID") %>'></asp:TextBox><br /> 
      Name :<asp:TextBox ID="txtname" runat="server" Text='<%# Bind("FBName") %>'></asp:TextBox> 
      LatLong:<asp:TextBox ID="txtlatlong" runat="server" Text='<%# Bind("LatLng") %>'></asp:TextBox><br /> 
      Address: <asp:DropDownList ID="ddlAddress" runat="server" OnDataBound="ddlAddress_DataBound" AppendDataBoundItems="true"> 
         <asp:ListItem Text="Select" Value="0"></asp:ListItem> 
         </asp:DropDownList> <br /> 
      Contact: <asp:TextBox ID="txtcontact" runat="server" Text='<%# Bind("ContactNumber") %>'></asp:TextBox><br /> 
      <asp:LinkButton ID="UpdateButton" 
       Text="Update" 
       CommandName="Update" 
       runat="server" /> 
      &nbsp; 
        <asp:LinkButton ID="CancelUpdateButton" 
         Text="Cancel" 
         CommandName="Cancel" 
         runat="server" /> 
     </EditItemTemplate> 
    </asp:FormView> 

C＃代码 -

public partial class Fifthpage : System.Web.UI.Page 
{ 
    protected void Page_Load(object sender, EventArgs e) 
    { 
     if (!IsPostBack) 
     { 
      lblshow.Text = Request.QueryString["q"].ToString(); 
Dataset ds = new Dataset();     
ds = bind(); 
      da.Fill(ds); 
      formview1.DataSource = ds; 
      formview1.DataBind(); 
     } 
    } 
    public DataSet bind() 
    { 
     SqlConnection con = new SqlConnection(); 
     con.ConnectionString = "Data Source=SYSTEM-PC;Initial Catalog=DB;Integrated Security=True"; 
     SqlCommand cmd = new SqlCommand("select * from FireBrigade",con); 
     SqlDataAdapter da = new SqlDataAdapter(cmd); 
     DataSet ds = new DataSet(); 
     da.Fill(ds); 
     return ds; 
    } 
    protected void ddlAddress_DataBound(object sender, EventArgs e) 
    { 
     DataSet ds = new DataSet(); 
     ds = bind(); 
     List<string> ls = new List<string>(); 
     foreach (ListItem lst in ds.Tables[0].Rows) 
     { 
      //lst.Value = ds.Tables[0].Rows[0]["Address"].ToString(); 
      ls.Add(ds.Tables[0].Rows[0]["Address"].ToString()); 
     } 
     DropDownList ddladd = (DropDownList)formview1.FindControl("ddlAddress"); 
     ddladd.DataSource = ls; 
    } 

    protected void formview1_ModeChanging(object sender, FormViewModeEventArgs e) 
    { 
     formview1.ChangeMode(e.NewMode); 
     bind(); 
    } 

    protected void formview1_PageIndexChanging(object sender, FormViewPageEventArgs e) 
    { 
     formview1.PageIndex = e.NewPageIndex; 
     bind(); 
    } 
} 

Answer 1

你应该编辑后重新分配FormView控件的数据源，所以只要改变你的代码如下

protected void formview1_ModeChanging(object sender, FormViewModeEventArgs e) 
{ 
    formview1.ChangeMode(e.NewMode); 
    formview1.DataSource = bind(); 
    formview1.DataBind(); 
}