GridView内のDropDownListがオブジェクトとして認識されていません

Question

ここで間違っていることを理解できません。グリッドビュー内のドロップダウンリストを動的に入力しようとすると、オブジェクト参照がオブジェクトのインスタンスに設定されていないことがわかります。

まず、私のASPX：

<asp:Panel runat="server" ID="ShowDiv3" Visible="false" BorderStyle="Solid" BorderWidth="0" Width="1389px"> 
     <asp:Label ID="lblShowDiv3Title" runat="server" Text="Root Causes: " Font-Bold="true"></asp:Label><asp:DropDownList ID="ddlRootCauses" runat="server" Width="300px" OnSelectedIndexChanged="ddlRootCauses_SelectedIndexChanged" AutoPostBack="true"></asp:DropDownList> 
     <br /> 
     <%-- This line needed to be commented out when paging was removed: AllowPaging="True" AllowCustomPaging="True" PageSize="10" --%> 
     <div id="divGrid3" style='width:1290px; overflow:auto'> 
    <asp:GridView ID="DataGrid_RootCauses" runat="server" 
     AllowSorting="True" OnSorting="DataGrid_RootCauses_Sorting" AutoGenerateColumns="False" ShowFooter ="true" CellPadding="1" 
     CssClass="hoverTable" 
     HeaderStyle-BackColor="#4DA6A6" HeaderStyle-BorderColor="#4DA6A6" 
     HeaderStyle-Font-Size="Small" HeaderStyle-ForeColor="White" 
     FooterStyle-BackColor="#4DA6A6" FooterStyle-BorderColor="#4DA6A6" FooterStyle-ForeColor="White" 
     DataKeyNames="root_cause_id" 
         OnRowDataBound="DataGrid_RootCauses_RowDataBound" 
     OnRowCancelingEdit="DataGrid_RootCauses_CancelCommand" 
     OnRowEditing="DataGrid_RootCauses_EditCommand" 
     OnRowDeleting="DataGrid_RootCauses_DeleteCommand" 
     OnRowUpdating="DataGrid_RootCauses_UpdateCommand"> 
      <Columns> 

      <asp:TemplateField HeaderText="LPI Due"> 
      <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_LPI_DUE" runat="server" Width="70px" Text='<%#Eval("LPI_DUE") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_LPI_DUE" runat="server" Width="70px" Text='<%#Eval("LPI_DUE") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_LPI_DUE" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField>      

     <asp:TemplateField HeaderText="Root Cause Category"> 
      <ItemTemplate> 
       <asp:Label ID="lbl_LPI_Category" runat="server" Width="170px" Text='<%#Eval("LPI_Category") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_LPI_Category" runat="server" Width="170px" Text='<%#Eval("LPI_Category") %>'></asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_LPI_Category" runat="server" Width="170px" ></asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField>     

     <asp:TemplateField HeaderText="Root Cause Reason"> 
      <ItemTemplate> 
       <asp:Label ID="lbl_LPI_Reason" runat="server" Width="370px" Text='<%#Eval("LPI_reason") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:TextBox ID="txt_RC_LPI_Reason" runat="server" Width="370px" Text='<%#Eval("LPI_reason") %>'></asp:TextBox> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:TextBox ID="ntxt_RC_LPI_Reason" runat="server" Width="370px" ></asp:TextBox> 
      </FooterTemplate> 
     </asp:TemplateField>     

     <asp:TemplateField HeaderText="Business Owned"> 
      <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_Business" runat="server" Width="70px" Text='<%#Eval("Business") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_Business" runat="server" Width="70px" Text='<%#Eval("Business") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_Business" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField> 

     <asp:TemplateField HeaderText="CP Owned"> 
     <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_CP" runat="server" Width="70px" Text='<%#Eval("CP") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_CP" runat="server" Width="70px" Text='<%#Eval("CP") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_CP" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField>      

     <asp:TemplateField HeaderText="Non-CP Owned"> 
     <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_Non_CP" runat="server" Width="70px" Text='<%#Eval("Non_CP") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_Non_CP" runat="server" Width="70px" Text='<%#Eval("Non_CP") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_Non_CP" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField> 

     <asp:TemplateField HeaderText="Proclaim"> 
     <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_Proclaim" runat="server" Width="70px" Text='<%#Eval("Proclaim") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_Proclaim" runat="server" Width="70px" Text='<%#Eval("Proclaim") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_Proclaim" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField> 

     <asp:TemplateField HeaderText="PMHS"> 
     <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_PMHS" runat="server" Width="70px" Text='<%#Eval("PMHS") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_PMHS" runat="server" Width="70px" Text='<%#Eval("PMHS") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_PMHS" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField> 

     <asp:TemplateField HeaderText="Facets"> 
     <ItemStyle HorizontalAlign="Center"></ItemStyle> 
      <ItemTemplate> 
       <asp:Label ID="lbl_Facets" runat="server" Width="70px" Text='<%#Eval("Facets") %>'></asp:Label> 
      </ItemTemplate> 
      <EditItemTemplate> 
       <asp:DropDownList ID="ddl_RC_Facets" runat="server" Width="70px" Text='<%#Eval("Facets") %>'> 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </EditItemTemplate> 
      <FooterTemplate> 
       <asp:DropDownList ID="nddl_RC_Facets" runat="server" Width="70px" > 
        <asp:ListItem Value=""> - </asp:ListItem> 
        <asp:ListItem Value="N"> N </asp:ListItem> 
        <asp:ListItem Value="Y"> Y </asp:ListItem> 
       </asp:DropDownList> 
      </FooterTemplate> 
     </asp:TemplateField> 

     <asp:TemplateField ItemStyle-Width="90px"> 
     <ItemTemplate> 
      <asp:Button ID="btn_Edit" runat="server" Text="Edit" CommandName="Edit" /> 
     </ItemTemplate> 
     <EditItemTemplate> 
      <asp:Button ID="btn_Update" runat="server" Text="Update" CommandName="Update"/> 
      <asp:Button ID="btn_Cancel" runat="server" Text="Cancel" CommandName="Cancel"/> 
     </EditItemTemplate> 
     <FooterTemplate> 
      <asp:Button ID="btn_Add" runat="server" Text="Add" OnClick="DataGrid_RootCauses_RowCreated" /> 
     </FooterTemplate> 
     </asp:TemplateField> 
     <asp:TemplateField> 
     <ItemTemplate> 
      <asp:Button ID="btn_Delete" runat="server" OnClientClick="javascript:return confirm('Are you sure?');" Text="Delete" CommandName="Delete" /> 
     </ItemTemplate> 
     </asp:TemplateField>   
     <asp:TemplateField HeaderText="Cause ID"> 
     <ItemTemplate> 
      <asp:Label ID="lbl_Cause_ID" runat="server" Text='<%#Eval("root_cause_id") %>'></asp:Label> 
     </ItemTemplate> 
     </asp:TemplateField>   

     </Columns> 
    </asp:GridView> 
    <asp:Label ID="lblEmpty1" runat="server" Visible="false" Style="font-weight:bold; font-size:large;"></asp:Label> 
    </div> 
</asp:Panel> 

さて、コードビハインドは：

奇妙な

protected void ddlRootCauses_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    LoadRootCauseGrid(); 

    OracleConnection conn = GetConnection(); 
    try 
    { 
     { 
      // ddlRootCauses 
      OracleCommand cmd6 = new OracleCommand(); 
      cmd6.CommandType = CommandType.StoredProcedure; 
      cmd6.CommandText = "SP_LPI_MAINT_LIST_ROOTCAUSE"; 
      cmd6.Connection = conn; 

      //cmd3.Parameters.Add("v_Lookup_Value", OracleType.VarChar, 20).Value = "LEAD"; 
      cmd6.Parameters.Add("vRootCauseList", OracleType.Cursor).Direction = ParameterDirection.Output; 

      var SearchAdapter6 = new OracleDataAdapter(cmd6); 
      var ds6 = new DataTable(); 
      SearchAdapter6.Fill(ds6); 

      DataView view = new DataView(ds6); 
      DataTable distinctValues = new DataTable(); 
      distinctValues = view.ToTable(true, "LPI_Category"); 

      // Fill all of the dropdowns from the same data adapter 
      { 
       //This one works fine 
       ddlRootCauses.DataSource = distinctValues; 
       ddlRootCauses.DataTextField = "LPI_Category"; 
       ddlRootCauses.DataValueField = "LPI_Category"; 
       ddlRootCauses.DataBind(); 
       ddlRootCauses.Items.Insert(0, new ListItem("All", "")); 

       //This one send me down to the Catch block on the first line 
       ddl_RC_LPI_Category.DataSource = distinctValues; 
       ddl_RC_LPI_Category.DataTextField = "LPI_Category"; 
       ddl_RC_LPI_Category.DataValueField = "LPI_Category"; 
       ddl_RC_LPI_Category.DataBind(); 
       ddl_RC_LPI_Category.Items.Insert(0, new ListItem("All", "")); 

       nddl_RC_LPI_Category.DataSource = distinctValues; 
       nddl_RC_LPI_Category.DataTextField = "LPI_Category"; 
       nddl_RC_LPI_Category.DataValueField = "LPI_Category"; 
       nddl_RC_LPI_Category.DataBind(); 
       nddl_RC_LPI_Category.Items.Insert(0, new ListItem("All", "")); 

      } 

      ds6.Dispose(); 
      cmd6.Dispose(); 
      SearchAdapter6.Dispose(); 

      conn.Close(); 
     } 
    } 
    catch (Exception ex) 
    { 
      Response.Write(ex.Message); 
      conn.Close(); 
    } 

} 

、ddlRootCausesは問題なく読み込まれます。しかし、そのドロップダウンリストはグリッドビューの外にあります。グリッドビュー内のドロップダウンリストに問題がある理由はわかりません。 そしては、gridviewsがドロップダウンを好きではないためです。ハードコードされたリスト項目を持つY/Nのものは正常に動作します。

Answer 1

コントロールがGridViewの内部にあるので、あなたはそれの外にあるContol（ddlRootCausesのような）

は、あなたが最初にFindControlでそれらを見つける必要があるGridViewの内側のDropDownListを移入するでしょう、あなたのようにそれらにアクセスすることはできません。 RowDataBound

まずASPX

<asp:GridView ID="GridView1" runat="server" OnRowDataBound="GridView1_RowDataBound" ShowFooter="true"> 
    <Columns> 
    <asp:TemplateField HeaderText="Root Cause Reason"> 
     <ItemTemplate> 
      <asp:DropDownList ID="DropDownListItem" runat="server"></asp:DropDownList> 
     </ItemTemplate> 
     <EditItemTemplate> 
      <asp:DropDownList ID="DropDownListEditItem" runat="server"></asp:DropDownList> 
     </EditItemTemplate> 
     <FooterTemplate> 
      <asp:DropDownList ID="DropDownListFooter" runat="server"></asp:DropDownList> 
     </FooterTemplate> 
    </asp:TemplateField> 
    </Columns> 
</asp:GridView> 

そして

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e) 
{ 
    if (e.Row.RowType == DataControlRowType.Header) 
    { 
     //the header row 
    } 
    else if (e.Row.RowType == DataControlRowType.DataRow) 
    { 
     //normal row 
     if ((e.Row.RowState & DataControlRowState.Edit) > 0) 
     { 
      //normal row in edit mode 
      DropDownList ddl = e.Row.FindControl("DropDownListEditItem") as DropDownList; 

      ddl.DataSource = distinctValues; 
      ddl.DataTextField = "myValue"; 
      ddl.DataValueField = "ID"; 
      ddl.DataBind(); 
     } 
     else 
     { 
      //normal row 
      DropDownList ddl = e.Row.FindControl("DropDownListItem") as DropDownList; 

      ddl.DataSource = distinctValues; 
      ddl.DataTextField = "myValue"; 
      ddl.DataValueField = "ID"; 
      ddl.DataBind(); 
     } 
    } 
    else if (e.Row.RowType == DataControlRowType.Footer) 
    { 
     //footer row 
     DropDownList ddl = e.Row.FindControl("DropDownListFooter") as DropDownList; 

     ddl.DataSource = distinctValues; 
     ddl.DataTextField = "myValue"; 
     ddl.DataValueField = "ID"; 
     ddl.DataBind(); 
    } 
} 

やボタンのクリックで背後にあるコードで

protected void ddlRootCauses_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    //find the dropdownlist in the footer row 
    DropDownList ddl = DataGrid_RootCauses.FooterRow.FindControl("nddl_RC_LPI_Category") as DropDownList; 

    //or in a normal row you need to use an index 
    DropDownList ddl = DataGrid_RootCauses.Rows[5].FindControl("ddl_RC_LPI_Category") as DropDownList; 

    ddl.DataSource = distinctValues; 
    ddl.DataTextField = "LPI_Category"; 
    ddl.DataValueField = "LPI_Category"; 
    ddl.DataBind(); 
    ddl.Items.Insert(0, new ListItem("All", "")); 
} 

例。

protected void Button1_Click(object sender, EventArgs e) 
{ 
    foreach (GridViewRow row in GridView1.Rows) 
    { 
     if (row.RowType == DataControlRowType.DataRow) 
     { 
      DropDownList ddl = row.FindControl("DropDownListItem") as DropDownList; 

      ddl.DataSource = Common.LoadFromDB(); 
      ddl.DataTextField = "field01"; 
      ddl.DataValueField = "itemID"; 
      ddl.DataBind(); 
     } 
    } 
}