从ASP动态添加和删除行.显示数据表格

Question

我已经使用下面的代码从网络" codeproject "为"动态添加和删除行从ASP。. NET GridView"，它使用了2个代码"AddNewRow"，"SetPreviouseData"。我在理解"SetPreviouseData"的代码有问题，似乎一切都将与"AddNewRow"代码当它定义

grvStudentDetails.DataSource = dtCurrentTable;
grvStudentDetails.DataBind();

实际上我不知道"SetPreviouseData"代码的用法，当已经定义了数据源之前。

    private void AddNewRow()
{
    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++)
            {
                TextBox TextBoxName = (TextBox)grvStudentDetails.Rows[rowIndex].Cells[1].FindControl("txtName");
                TextBox TextBoxAge = (TextBox)grvStudentDetails.Rows[rowIndex].Cells[2].FindControl("txtAge");
                TextBox TextBoxAddress = 
                  (TextBox)grvStudentDetails.Rows[rowIndex].Cells[3].FindControl("txtAddress");
                RadioButtonList RBLGender = 
                  (RadioButtonList)grvStudentDetails.Rows[rowIndex].Cells[4].FindControl("RBLGender");
                DropDownList DrpQualification = 
                  (DropDownList)grvStudentDetails.Rows[rowIndex].Cells[5].FindControl("drpQualification");
                drCurrentRow = dtCurrentTable.NewRow();
                drCurrentRow["RowNumber"] = i + 1;
                dtCurrentTable.Rows[i - 1]["Col1"] = TextBoxName.Text;
                dtCurrentTable.Rows[i - 1]["Col2"] = TextBoxAge.Text;
                dtCurrentTable.Rows[i - 1]["Col3"] = TextBoxAddress.Text;
                dtCurrentTable.Rows[i - 1]["Col4"] = RBLGender.SelectedValue;
                dtCurrentTable.Rows[i - 1]["Col5"] = DrpQualification.SelectedValue;
                rowIndex++;
            }
            dtCurrentTable.Rows.Add(drCurrentRow);
            ViewState["CurrentTable"] = dtCurrentTable;
            grvStudentDetails.DataSource = dtCurrentTable;
            grvStudentDetails.DataBind();
        }
    }
    else
    {
        Response.Write("ViewState is null");
    }
    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 TextBoxName =  (TextBox)grvStudentDetails.Rows[rowIndex].Cells[1].FindControl("txtName");
                TextBox TextBoxAge = (TextBox)grvStudentDetails.Rows[rowIndex].Cells[2].FindControl("txtAge");
                TextBox TextBoxAddress = (TextBox)grvStudentDetails.Rows[rowIndex].Cells[3].FindControl("txtAddress");
                RadioButtonList RBLGender = (RadioButtonList)grvStudentDetails.Rows[rowIndex].Cells[4].FindControl("RBLGender");
                DropDownList DrpQualification = (DropDownList)grvStudentDetails.Rows[rowIndex].Cells[5].FindControl("drpQualification");
                TextBoxName.Text = dt.Rows[i]["Col1"].ToString();
                TextBoxAge.Text = dt.Rows[i]["Col2"].ToString();
                TextBoxAddress.Text = dt.Rows[i]["Col3"].ToString();
                RBLGender.SelectedValue = dt.Rows[i]["Col4"].ToString();
                DrpQualification.SelectedValue = dt.Rows[i]["Col5"].ToString();
                rowIndex++;
            }
        }
    }
    }

Answer 1

从代码中，AddNewRow已经很清楚了，而SetPreviouseData似乎用于显示最后的数据到组件(TextBox, RadioButtonList, DropDownList)。

    // Get the reference to the objects (TextBoxes, RadioButtonList, DropDownList)
    TextBox TextBoxName =  (TextBox)grvStudentDetails.Rows[rowIndex].Cells[1].FindControl("txtName");
    TextBox TextBoxAge = (TextBox)grvStudentDetails.Rows[rowIndex].Cells[2].FindControl("txtAge");
    TextBox TextBoxAddress = (TextBox)grvStudentDetails.Rows[rowIndex].Cells[3].FindControl("txtAddress");
    RadioButtonList RBLGender = (RadioButtonList)grvStudentDetails.Rows[rowIndex].Cells[4].FindControl("RBLGender");
    DropDownList DrpQualification = (DropDownList)grvStudentDetails.Rows[rowIndex].Cells[5].FindControl("drpQualification");
    // Set the value of the objects to the last on the DataTable
    TextBoxName.Text = dt.Rows[i]["Col1"].ToString();
    TextBoxAge.Text = dt.Rows[i]["Col2"].ToString();
    TextBoxAddress.Text = dt.Rows[i]["Col3"].ToString();
    RBLGender.SelectedValue = dt.Rows[i]["Col4"].ToString();
    DrpQualification.SelectedValue = dt.Rows[i]["Col5"].ToString();