Question

我在本教程中找到了以下代码：

http://geekswithblogs.net/dotNETvinz/archive/2009/06/04/adding-dynamic-rows-in-gridview-with-textboxes.aspx

Default.aspx的

<asp:gridview ID="Gridview1" runat="server" ShowFooter="true"
                             AutoGenerateColumns="false">
        <Columns>
        <asp:BoundField DataField="RowNumber" HeaderText="Row Number" />
        <asp:TemplateField HeaderText="Header 1">
            <ItemTemplate>
                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Header 2">
            <ItemTemplate>
                <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Header 3">
            <ItemTemplate>
                 <asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
            </ItemTemplate>
            <FooterStyle HorizontalAlign="Right" />
            <FooterTemplate>
                 <asp:Button ID="ButtonAdd" runat="server" Text="Add New Row" onclick="ButtonAdd_Click" />
            </FooterTemplate>
        </asp:TemplateField>
        </Columns>
</asp:gridview>

Default.aspx.cs

protected void Page_Load(object sender, EventArgs e){
        if (!Page.IsPostBack){
            SetInitialRow();  
        }
}


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; 
                    drCurrentRow["Column1"] = box1.Text;
                    drCurrentRow["Column2"] = box2.Text;
                    drCurrentRow["Column3"] = box3.Text;

                    rowIndex++;
                }

                //add new row to DataTable
                dtCurrentTable.Rows.Add(drCurrentRow);
                //Store the current data to ViewState
                ViewState["CurrentTable"] = dtCurrentTable;

                //Rebind the Grid with the current data
                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 = 1; 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 ButtonAdd_Click(object sender, EventArgs e){
        AddNewRowToGrid();
}

现在的问题是，让我们说当初始网格出现并添加一些数据然后点击添加行。我在该行中添加的数据保持不变。但现在，让我说我添加了5行，然后我去第3行，我添加一些数据，然后点击添加行，数据消失，永远不会显示。只有在最后一行添加数据然后单击添加行时，才会显示数据。有谁知道为什么会这样？

Answer 1

由于这个循环，它正在发生：

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; 
    drCurrentRow["Column1"] = box1.Text;
    drCurrentRow["Column2"] = box2.Text;
    drCurrentRow["Column3"] = box3.Text;

    rowIndex++;
}

它遍历数据表中的所有行并构建一个drCurrentRow对象，但它只是在循环之外添加drCurrentRow对象：

//add new row to DataTable
dtCurrentTable.Rows.Add(drCurrentRow);

因此drCurrentRow的内容是最后一行。

更新：

为了解决这个问题，我建议您这样做，这样一次只能添加一行，然后不是循环遍历数据表中的所有行，只需从最后一行获取数据并将其用作要添加到数据表的“新”行的数据，如下所示：

//extract the TextBox values
TextBox box1 = (TextBox)Gridview1.Rows[dtCurrentTable.Rows.Count - 1].Cells[1].FindControl("TextBox1");
TextBox box2 = (TextBox)Gridview1.Rows[dtCurrentTable.Rows.Count - 1].Cells[2].FindControl("TextBox2");
TextBox box3 = (TextBox)Gridview1.Rows[dtCurrentTable.Rows.Count - 1].Cells[3].FindControl("TextBox3");

drCurrentRow = dtCurrentTable.NewRow();
drCurrentRow["RowNumber"] = dtCurrentTable.Rows.Count + 1; 
drCurrentRow["Column1"] = box1.Text;
drCurrentRow["Column2"] = box2.Text;
drCurrentRow["Column3"] = box3.Text;

//add new row to DataTable
dtCurrentTable.Rows.Add(drCurrentRow);

未在文本框中添加值

1 个答案: