如何使用ASP.NET C＃Webform中的每个foreach循环在DataSet中添加DataTable值

Question

How to Add DataTable value in DataSet Using every foreach loop in ASP.NET C# Webform, Actually I have one gridview and in gridview selected checkbox data should only download to xl.

I have below code for export to xl button.

     foreach (GridViewRow row in gv_TotalAllReg.Rows)
        {
            if (row.RowType == DataControlRowType.DataRow)
            {
                bool isChecked = ((CheckBox)row.FindControl("chk_box")).Checked;
                if (isChecked == true)
                {
                    //var ds = new DataSet();
                    //var dt = new DataTable("RegistrationDetails");

                    int index = row.RowIndex;

                    bo.Para1 = "4";
                    bo.Para2 = "Innovation";

                    bo.Para3 = gv_TotalAllReg.DataKeys[index].Values[0].ToString();//Id



                }
            }
        }
        dt = bl.Admin_GetInnovationbaseonParaType(bo);
        if (gv_TotalAllReg.Rows.Count > 0)
        {
            dt.TableName = "RegistrationDetails";
            ds.Tables.Add(dt);
            ExcelHelper.ToExcel(ds, "ApplicationDetails.xls", Page.Response);
            btnExport.Visible = true;


        }

Actually base on selected checkbox in gridview that data is not showing in xl sheet, only last selected data is showing in xl sheet.

I am not getting logic ds.Tables.Add(dt); to add dt values in ds every foreach loop. I need all selected data into xl sheet. Why last select data only coming in xl sheet.

Answer 1

Instead of adding each row of datatable to dataset you can add entire datatable to dataset .

Dataset can hold collection of datatables so you can add multiple datatable to dataset.

DataTable tbl = new Datatable();//or your method that returns datatable.
DataSet ds = new DataSet(); //new dataset object
ds.Tables.Add(tbl); //add datatable object in dataset object.

Update

 DataTable dt= new DataTable();
//Columns that should present in datatable
dt.Columns.Add("SN");
dt.Columns.Add("MyField");
int sn = 1;
foreach (GridViewRow row in gv_TotalAllReg.Rows)
{
    if (row.RowType == DataControlRowType.DataRow)
    {
        bool isChecked = ((CheckBox)row.FindControl("chk_box")).Checked;
        if (isChecked == true)
        {
            DataRow row = dt.NewRow();
            //Add necessary columns to row by index.
            row[0] = sn;
            row[1] = gv_TotalAllReg.DataKeys[index].Values[0].ToString();   
            dt.Rows.Add(row); 
            sn++;
        }
    }
}
if (tbl .Rows.Count > 0)
{
ds.Tables.Add(dt);
ExcelHelper.ToExcel(ds, "ApplicationDetails.xls", Page.Response);
btnExport.Visible = true;
}

Answer 2

I think you can crete DataTable before foreach loop, and add rows inside it. Here is an example with adding and retrieving data from DataTable :

DataTable dt = bl.Admin_GetInnovationbaseonParaType(bo);
if (gv_TotalAllReg.Rows.Count > 0)
{
     dt.TableName = "RegistrationDetails";
     ds.Tables.Add(dt);               

     foreach (GridViewRow row in gv_TotalAllReg.Rows)
     {
         if (row.RowType == DataControlRowType.DataRow)
         {
             bool isChecked = ((CheckBox)row.FindControl("chk_box")).Checked;
             if (isChecked == true)
             {                    
                // inserting data row
                dr = dt.NewRow();
                dr.SetField("Column_Name", "your_Value");
                dt.Rows.Add(dr);

                int index = row.RowIndex;

                bo.Para1 = "4";
                bo.Para2 = "Innovation";

                bo.Para3 = gv_TotalAllReg.DataKeys[index].Values[0].ToString();//Id
             }
         }
    }

    ExcelHelper.ToExcel(ds, "ApplicationDetails.xls", Page.Response);
    btnExport.Visible = true;
}

Retrieving data:

string[] values = dt.AsEnumerable().Select(r => r.Field<string>("Value")).ToArray();