我正在从网格视图中删除行，但表中的所有数据都被删除

Question

我想在Gridview中动态添加和删除行。添加成功。当删除该行时，该行删除成功。但在其他行中输入的数据将被清除。我想删除行。我还想防止先前输入的数据被删除。

default . aspx

<asp:GridView ID="Gridview1" runat="server" AutoGenerateColumns="False" OnSelectedIndexChanged="Gridview1_SelectedIndexChanged">
<Columns>
<asp:BoundField DataField="RowNumber" HeaderText="Row Number" />
<asp:TemplateField HeaderText="Header 2">
<ItemTemplate>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Header 3">
<ItemTemplate>
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Header 4">
<ItemTemplate>
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField ControlStyle-CssClass="row-edit" HeaderText="">
<ItemTemplate>
<asp:LinkButton ID="LinkButton1" CommandName="Select" runat="server"><i class="fas fa-times"></i></asp:LinkButton>
</ItemTemplate>
<ControlStyle CssClass="row-edit"></ControlStyle>
</asp:TemplateField>
</Columns>
</asp:GridView>
<asp:Button ID="ButtonAdd" runat="server" Text="Add New Row" OnClick="ButtonAdd_Click" />

Default.aspx.cs

private void SetInitialRow()
{
DataTable dt = new DataTable();
DataRow dr = null;
dt.Columns.Add(new DataColumn("RowNumber", typeof(string)));
dt.Columns.Add(new DataColumn("Column1", typeof(string)));
dt.Columns.Add(new DataColumn("Column2", typeof(string)));
dt.Columns.Add(new DataColumn("Column3", typeof(string)));
dr = dt.NewRow();
dr["RowNumber"] = 1;
dr["Column1"] = string.Empty;
dr["Column2"] = string.Empty;
dr["Column3"] = string.Empty;
dt.Rows.Add(dr);
//Store the DataTable in ViewState
ViewState["CurrentTable"] = dt;
Gridview1.DataSource = dt;
Gridview1.DataBind();
}
private void AddNewRowToGrid()
{
int rowIndex = 0;
if (ViewState["CurrentTable"] != null)
{
DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
DataRow drCurrentRow = null;
if (dtCurrentTable.Rows.Count > 0)
{
for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)
{
//extract the TextBox values
TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
drCurrentRow = dtCurrentTable.NewRow();
drCurrentRow["RowNumber"] = i + 1;
dtCurrentTable.Rows[i - 1]["Column1"] = box1.Text;
dtCurrentTable.Rows[i - 1]["Column2"] = box2.Text;
dtCurrentTable.Rows[i - 1]["Column3"] = box3.Text;
rowIndex++;
}
dtCurrentTable.Rows.Add(drCurrentRow);
ViewState["CurrentTable"] = dtCurrentTable;
Gridview1.DataSource = dtCurrentTable;
Gridview1.DataBind();
}
}
else
{
Response.Write("ViewState is null");
}
//Set Previous Data on Postbacks
SetPreviousData();
}
private void SetPreviousData()
{
int rowIndex = 0;
if (ViewState["CurrentTable"] != null)
{
DataTable dt = (DataTable)ViewState["CurrentTable"];
if (dt.Rows.Count > 0)
{
for (int i = 0; i < dt.Rows.Count; i++)
{
TextBox box1 = (TextBox)Gridview1.Rows[rowIndex].Cells[1].FindControl("TextBox1");
TextBox box2 = (TextBox)Gridview1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
TextBox box3 = (TextBox)Gridview1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
box1.Text = dt.Rows[i]["Column1"].ToString();
box2.Text = dt.Rows[i]["Column2"].ToString();
box3.Text = dt.Rows[i]["Column3"].ToString();
rowIndex++;
}
}
}
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
SetInitialRow();
}
}
protected void ButtonAdd_Click(object sender, EventArgs e)
{
AddNewRowToGrid();
}
protected void Gridview1_SelectedIndexChanged(object sender, EventArgs e)
{
int indis = Gridview1.SelectedIndex;
GridViewRow satir = Gridview1.Rows[indis];
DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];
DataRow[] _row = dtCurrentTable.Select("RowNumber=" + satir.Cells[0].Text);
foreach (DataRow row in _row)
{
row.Delete();
}
dtCurrentTable.AcceptChanges();
ViewState["CurrentTable"] = dtCurrentTable;
Gridview1.DataSource = dtCurrentTable;
Gridview1.DataBind();
}

问题在这里(它不允许我将它粘贴为平面图像。)我的问题

Answer 1

我们每次只删除一行，对吧?

好的，根据反馈，需要/想要这个标记:

<asp:GridView ID="Gridview1" runat="server" AutoGenerateColumns="False">
<Columns>
<asp:BoundField DataField="RowNumber" HeaderText="Row Number" />
<asp:TemplateField HeaderText="Header 2">
<ItemTemplate>
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Eval("Column1") %>' ></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Header 3">
<ItemTemplate>
<asp:TextBox ID="TextBox2" runat="server" Text='<%# Eval("Column2") %>' ></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Header 4">
<ItemTemplate>
<asp:TextBox ID="TextBox3" runat="server" Text='<%# Eval("Column3") %>' ></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Delete" ItemStyle-HorizontalAlign="Center" >
<ItemTemplate>
<asp:Button ID="cmdDel" runat="server" Text="Delete" OnClick="cmdDel_Click"
OnClientClick="return confirm('Delete this row? (cannot undo)');"/>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
<br />
<asp:Button ID="ButtonAdd" runat="server" Text="Add New Row" OnClick="ButtonAdd_Click" />
<asp:Button ID="cmdSave" runat="server" Text="Save Grid to Table" Style="margin-left:30px" OnClick="cmdSave_Click"/>

代码如下:

DataTable dt = new DataTable();
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
CreateTable();
AddRow();
LoadGrid();
ViewState["MyTable"] = dt;
}
else
{
dt = (DataTable)ViewState["MyTable"];
}
}
void CreateTable()
{
dt.Columns.Add(new DataColumn("RowNumber", typeof(int)));
dt.Columns[0].AutoIncrementSeed = 1;
dt.Columns[0].AutoIncrementStep = 1;
dt.Columns[0].AutoIncrement = true;
dt.Columns.Add(new DataColumn("Column1", typeof(string)));
dt.Columns.Add(new DataColumn("Column2", typeof(string)));
dt.Columns.Add(new DataColumn("Column3", typeof(string)));
}
void AddRow()
{
DataRow dr = dt.NewRow();
dr["Column1"] = "";
dr["Column2"] = "";
dr["Column3"] = "";
dt.Rows.Add(dr);
}
void LoadGrid()
{
// Gridview1.Columns.Clear();
Gridview1.DataSource = dt;
Gridview1.DataBind();
}
protected void ButtonAdd_Click(object sender, EventArgs e)
{
SaveData();
AddRow();
LoadGrid();
}
void SaveData()
{
// move grid changes back to table
foreach (GridViewRow gvRow in Gridview1.Rows)
{
//extract the TextBox values
DataRow dr = dt.Rows[gvRow.RowIndex];
dr["Column1"] = ((TextBox)gvRow.FindControl("TextBox1")).Text;
dr["Column2"] = ((TextBox)gvRow.FindControl("TextBox2")).Text;
dr["Column3"] = ((TextBox)gvRow.FindControl("TextBox3")).Text;
}
dt.AcceptChanges();
}
protected void cmdSave_Click(object sender, EventArgs e)
{
SaveData();
}
protected void cmdDel_Click(object sender, EventArgs e)
{
Button cmdDel = (Button)sender;
GridViewRow gvRow = (GridViewRow)cmdDel.Parent.Parent;
dt.Rows[gvRow.RowIndex].Delete();
dt.AcceptChanges();
LoadGrid();
}

当然，实际使用中的保存按钮应该是"提交"。然后转到下一个网页，或者用户正在处理的任何任务。

我认为这只是为了学习，因为一张表只是坐在内存中几乎没有使用。我假设这个表来自一个数据库，否则这个设置就没有那么大的用处了。