[英]Grid view Dropdown list data binding error
我正在使用以下代碼從另一個表綁定下拉數據。 並且還使用rowindex引用該控件名稱。 但是它總是返回null並返回錯誤消息。
`Object reference not set to an instance of an object.`
我正在使用兩種方法,但是都返回控件名稱為null
第一個代碼:
protected void GridView2_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
Control ctrl = e.Row.FindControl("DDL_STATUS_FT"); //It always return null
if (ctrl != null)
{
DropDownList dd = ctrl as DropDownList;
DataSet7TableAdapters.sp_getall_trv_masterTableAdapter TA = new DataSet7TableAdapters.sp_getall_trv_masterTableAdapter();
DataSet7.sp_getall_trv_masterDataTable DS = TA.GetData();
dd.DataTextField = "fld_TName";
dd.DataValueField = "fld_id";
dd.DataSource = DS;
dd.DataBind();
}
}
}
第二:
In databind function
if (DS.Rows.Count > 0)
{
GridView2.DataSource = DS;
GridView2.DataBind();
foreach (GridViewRow grdRow in GridView2.Rows)
{
DataSet7TableAdapters.sp_getall_trv_masterTableAdapter TA1 = new DataSet7TableAdapters.sp_getall_trv_masterTableAdapter();
DataSet7.sp_getall_trv_masterDataTable DS1 = TA1.GetData();
// Nested DropDownList Control reference is passed to the DrdList object. This will allow you access the properties of dropdownlist placed inside the GridView Template column.
DropDownList drdList = (DropDownList)(GridView2.Rows[grdRow.RowIndex].Cells[4].FindControl("DDL_STATUS_FT"));//It always return null
// DataBinding of nested DropDownList Control for each row of GridView Control.
drdList.DataSource = DS1;
drdList.DataValueField = "fld_id";
drdList.DataTextField = "fld_TName";
drdList.DataBind();
}
}
請幫助我做到這一點。
<asp:TemplateField ItemStyle-Width="100px" HeaderText="TYPE">
<ItemTemplate>
<asp:DropDownList ID="DDL_STATUS" runat="server" AutoPostBack="true" Enabled="false" >
</asp:DropDownList>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="DDL_edit_STATUS" runat="server" AutoPostBack="true" SelectedValue='<%# Eval("fld_Type") %>'>
</asp:DropDownList>
</EditItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="DDL_STATUS_FT" runat="server" AutoPostBack="true">
</asp:DropDownList>
</FooterTemplate>
</asp:TemplateField>
下拉Footer Template
“ DDL_STATUS_FT”位於Footer Template
您必須按以下步驟進行檢查。
if(e.Row.RowType == DataControlRowType.Footer)
{
DropDownList ctrl =(DropDownList)e.Row.Cells[CellIndex].FindControl("DDL_STATUS_FT");
}
編輯2
您必須在gridview item-template的aspx代碼中具有dropdownlist
您正在發現使用e.row.findcontrol
沒有對其進行如此濫用地聲明它返回null
因此,首先將dropdownlist添加到您的gridview中,這是您的dropdownlist的示例
<asp:TemplateField ItemStyle-Width="30px" HeaderText="DDL_STATUS_FT">
<ItemTemplate>
<asp:Dropdownlist ID="DDL_STATUS_FT" runat="server" />
</ItemTemplate>
</asp:TemplateField>
如果您有空ctrl
控件ctrl = e.Row.FindControl(“ DDL_STATUS_FT”); //它總是返回null
然后確保在您的aspx代碼DDL_STATUS_FT
控件中運行runat="server"
嘗試通過cell和cellIndex查找控件,例如...
Control ctrl = e.Row.Cells[yourCellIndex].FindControl("DDL_STATUS_FT");
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