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時，這是this thread with how to build a DetailsView button that will check all the boxes in a given form.延續我試圖將先前的線程中得到援助，但沒有迴應這樣的新線程。選擇校驗按鈕錯誤保存到數據庫
截至目前，該複選框按鈕的工作原理沒有問題，但是當我去點擊「保存」按鈕，這條線在CS文件中出現的錯誤消息：
TextBox tb = FindControl<TextBox>(row.Cells[i].Controls);
if (tb != null)
{
table.Rows[0][j] = tb.Text;
}
與錯誤：
System.NullReferenceException：對象不設置爲一個對象的一個實例。
我很難過，因爲我在這裏做錯了。我在想我不知道這個過程如何在幕後完全運作。我一直在翻閱MSDN文檔，看看我是否能夠更好地解釋如何從理論上正確地將其保存到數據庫，但一直沒有找到合適的文檔來協助。
的SQL代碼是固體，沒有問題之前，我添加的複選框按鈕，代碼工作。
表格代號：
(Note some cosmetic code for the details view has been omitted)
<%@ Page Title="Test Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeFile="form2.aspx.cs" Inherits="form2" %>
<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="FeaturedContent" Runat="Server">
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="MainContent" Runat="Server">
<asp:DetailsView ID="DetailsView" runat="server" AutoGenerateColumns="False" CellPadding="4" DataSourceID="SqlDataSource1" ForeColor="#333333" GridLines="None">
<AlternatingRowStyle BackColor="White" />
<insert asp cosmetic gobbledy gook here>
<Fields>
<asp:BoundField DataField="Field_1" HeaderText="Ticket Number" SortExpression="Field_1" />
<asp:BoundField DataField="Field 2" HeaderText="Field 2" SortExpression="Field_2" />
<asp:BoundField DataField="Field_3" HeaderText="Field 3" SortExpression="Field_3" />
<asp:BoundField DataField="Field_4" HeaderText="Field 4" SortExpression="Field_4" />
<asp:BoundField DataField="Field_5" HeaderText="Field 5" SortExpression="Field_5" />
<asp:BoundField DataField="Field_6" HeaderText="Field 6" SortExpression="Field_6" />
<asp:BoundField DataField="Field_7" HeaderText="Field 7" SortExpression="Field_7" />
<asp:BoundField DataField="Field_8" HeaderText="Field 8" SortExpression="Field_8" />
<asp:BoundField DataField="Field_9" HeaderText="Field 9" SortExpression="Field_9" />
<asp:BoundField DataField="Field_10" HeaderText="Field 10" SortExpression="Field_10" />
<asp:CheckBoxField DataField="Check_Box_1" HeaderText="Check Box 1" SortExpression="Check_Box_1" />
<asp:CheckBoxField DataField="Check_Box_2" HeaderText="Check Box 2" SortExpression="Check_Box_2" />
<asp:CheckBoxField DataField="Check_Box_3" HeaderText="Check Box 3" SortExpression="Check_Box_3" />
<asp:CheckBoxField DataField="Check_Box_4" HeaderText="Check Box 4" SortExpression="Check_Box_4" />
<asp:CheckBoxField DataField="Check_Box_5" HeaderText="Check Box 5" SortExpression="Check_Box_5" />
<asp:CheckBoxField DataField="Check_Box_6" HeaderText="Check Box 6" SortExpression="Check_Box_6" />
<asp:CheckBoxField DataField="Check_Box_7" HeaderText="Check Box 7" SortExpression="Check_Box_7" />
<asp:CheckBoxField DataField="Check_Box_8" HeaderText="Check Box 8" SortExpression="Check_Box_8" />
<asp:CheckBoxField DataField="Check_Box_9" HeaderText="Check Box 9" SortExpression="Check_Box_9" />
<asp:CheckBoxField DataField="Check_Box_10" HeaderText="Check Box 10" SortExpression="Check_Box_10" />
<asp:CheckBoxField DataField="Check_Box_11" HeaderText="Check Box 11" SortExpression="Check_Box_11" />
<asp:CheckBoxField DataField="Check_Box_12" HeaderText="Check Box 12" SortExpression="Check_Box_12" />
<asp:CheckBoxField DataField="Check_Box_13" HeaderText="Check Box 13" SortExpression="Check_Box_13" />
<asp:CheckBoxField DataField="Check_Box_14" HeaderText="Check Box 14" SortExpression="Check_Box_14" />
<asp:CheckBoxField DataField="Check_Box_15" HeaderText="Check Box 15" SortExpression="Check_Box_15" />
<asp:CheckBoxField DataField="Check_Box_16" HeaderText="Check Box 16" SortExpression="Check_Box_16" />
<asp:CheckBoxField DataField="Check_Box_17" HeaderText="Check Box 17" SortExpression="Check_Box_17" />
<asp:CheckBoxField DataField="Check_Box_18" HeaderText="Check Box 18" SortExpression="Check_Box_18" />
<asp:CheckBoxField DataField="Check_Box_19" HeaderText="Check Box 19" SortExpression="Check_Box_19" />
<asp:ButtonField ButtonType="Button" CommandName="btnSelectAll" Text="Select/Check All Servers" >
<asp:BoundField DataField="Field_11" HeaderText="Field 11" SortExpression="Field_11" />
<asp:BoundField DataField="Field_12" HeaderText="Field 12" SortExpression="Field_12" />
<asp:BoundField DataField="Field_13" HeaderText="Field 13" SortExpression="Field_13" />
<asp:ButtonField ButtonType="Button" CommandName="btnCancel" Text="Cancel" />
<asp:ButtonField ButtonType="Button" CommandName="btnSave" Text="Save" />
<asp:CommandField ButtonType="Button" NewText="CreateRecord" ShowInsertButton="True" />
</Fields>
<more asp non essential cosmetic gobbledy gook>
</asp:DetailsView>
<asp:SqlDataSource ID="SqlDataSource1" ConnectionString="<%$ ConnectionStrings:test_form_connect %>" runat="server" InsertCommand="INSERT INTO [test].[detailsview_test_form] ([Field_1], [Field_2], [Field_3], [Field_4], [Field_5], [Field_6], [Field_7], [Field_8], [Field_9], [Field_10], [Check_Box_1], [Check_Box_2], [Check_Box_3], [Check_Box_4], [Check_Box_5], [Check_Box_6], [Check_Box_7], [Check_Box_8], [Check_Box_9], [Check_Box_10], [Check_Box_11], [Check_Box_12], [Check_Box_13], [Check_Box_14], [Check_Box_15], [Check_Box_16], [Check_Box_17], [Check_Box_18], [Check_Box_19], [Field_11], [Field_12], [Field_13]) VALUES (@Field_1, @Field_2, @Field_3, @Field_4, @Field_5, @Field_6, @Field_7, @Field_8, @Field_9, @Field_10, @Check_Box_1, @Check_Box_2, @Check_Box_3, @Check_Box_4, @Check_Box_5, @Check_Box_6, @Check_Box_7, @Check_Box_8, @Check_Box_9, @Check_Box_10, @Check_Box_11, @Check_Box_12, @Check_Box_13, @Check_Box_14, @Check_Box_15, @Check_Box_16, @Check_Box_17, @Check_Box_18, @Check_Box_19, @Field_11, @Field_12, @Field_13) ">
<InsertParameters>
<asp:Parameter Name="Field_1" />
<asp:Parameter Name="Field_2" />
<asp:Parameter Name="Field_3" />
<asp:Parameter Name="Field_4" />
<asp:Parameter Name="Field_5" />
<asp:Parameter Name="Field_6" />
<asp:Parameter Name="Field_7" />
<asp:Parameter Name="Field_8" />
<asp:Parameter Name="Field_9" />
<asp:Parameter Name="Field_10" />
<asp:Parameter Name="Check_Box_1" />
<asp:Parameter Name="Check_Box_2" />
<asp:Parameter Name="Check_Box_3" />
<asp:Parameter Name="Check_Box_4" />
<asp:Parameter Name="Check_Box_5" />
<asp:Parameter Name="Check_Box_6" />
<asp:Parameter Name="Check_Box_7" />
<asp:Parameter Name="Check_Box_8" />
<asp:Parameter Name="Check_Box_9" />
<asp:Parameter Name="Check_Box_10" />
<asp:Parameter Name="Check_Box_11" />
<asp:Parameter Name="Check_Box_12" />
<asp:Parameter Name="Check_Box_13" />
<asp:Parameter Name="Check_Box_14" />
<asp:Parameter Name="Check_Box_15" />
<asp:Parameter Name="Check_Box_16" />
<asp:Parameter Name="Check_Box_17" />
<asp:Parameter Name="Check_Box_18" />
<asp:Parameter Name="Check_Box_19" />
<asp:Parameter Name="Field_11" />
<asp:Parameter Name="Field_12" />
<asp:Parameter Name="Field_13" />
</InsertParameters>
</asp:SqlDataSource>
</asp:Content>
代碼隱藏
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
public partial class checkbox_dev : System.Web.UI.Page
{
DataTable m_table = null;
public DataTable table
{
get
{
if (ViewState["m_table"] != null)
return (DataTable)ViewState["m_table"];
else
return null;
}
set
{
ViewState["m_table"] = value;
}
}
public static T FindControl<T>(ControlCollection controls)
{
for (int i = 0; i < controls.Count; i++)
{
if (controls[i] is T)
return (T)(object)controls[i];
}
return default(T);
}
protected void Page_Load(object sender, EventArgs e)
//private static DataTable GetData(string sqlCommand)
{
string connectionString = GetConnectionString();
SqlConnection connection = new SqlConnection(connectionString);
}
static private string GetConnectionString()
{
return "(insert SQL Server connection Stringhere)";
}
protected void DetailsView1_ItemCommand(Object sender, DetailsViewCommandEventArgs e)
{
if (e.CommandName == "btnSelectAll")
{
foreach (DetailsViewRow row in DetailsView1.Rows)
{
for (int i = 0; i < row.Cells.Count; i++)
{
CheckBox cb = FindControl<CheckBox>(row.Cells[i].Controls);
if (cb != null)
{
cb.Checked = true;
}
}
}
}
if (e.CommandName == "btnSave")
{
int j = 0;
foreach (DetailsViewRow row in DetailsView1.Rows)
{
for (int i = 0; i < row.Cells.Count; i++)
{
TextBox tb = FindControl<TextBox>(row.Cells[i].Controls);
if (tb != null)
{
table.Rows[0][j] = tb.Text;
}
CheckBox cb = FindControl<CheckBox>(row.Cells[i].Controls);
if (cb != null)
{
table.Rows[0][j] = cb.Checked;
}
}
j++;
}
DetailsView1.ChangeMode(DetailsViewMode.ReadOnly);
DetailsView1.DataSource = table;
DetailsView1.DataBind();
}
if (e.CommandName == "btnEdit")
{
DetailsView1.ChangeMode(DetailsViewMode.Edit);
DetailsView1.DataSource = table;
DetailsView1.DataBind();
}
if (e.CommandName == "btnCancel")
{
DetailsView1.ChangeMode(DetailsViewMode.ReadOnly);
DetailsView1.DataSource = table;
DetailsView1.DataBind();
}
}
}
你確定'table'沒有返回null嗎？你的get方法有可能返回null，我會在它上面放一個斷點，看看它返回的是什麼。 – JuStDaN
在這一行中：「TextBox tb = FindControl（row.Cells [i] .Controls）;」在立即窗口中添加一個斷點，鍵入：「row.Cells [i]。控件「，如果它爲空，則輸入」row「以查看它是否爲空 –
User2012384
幾乎所有'NullReferenceException'的情況都是相同的，請參閱」[.NET中的什麼是NullReferenceException？]（http://stackoverflow.com/問題/ 4660142/what-is-a-nullreferenceexception-in-net）「的一些提示。 –