Question

I need to be able to generate a basic CSV file of the results returned from an SqlDataSource/GridView upon the user clicking a button, then allow them to save this file.

Is this simple to do?

Thanks

Answer 1

Since you are using a SqlDataSource then you can get a DataTable out of it like this:

var dv = new DataView();
var dt = new DataTable();
dv = (DataView)mySQLDataSource.Select(DataSourceSelectArguments.Empty);
dt = dv.ToTable();

I wrote a set of extension methods to do DataTable to CSV, which you should be able to use easily.

The rest of your code would be pretty simple then:

var csv = dt.ToCSV();

Here is a full example using this very method.

The Markup:

<%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeBehind="Default.aspx.cs" Inherits="SO.WebUI._Default" %>

<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">
</asp:Content>
<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="EmployeeId"
        DataSourceID="SqlDataSourceLocal">
        <Columns>
            <asp:BoundField DataField="EmployeeId" HeaderText="EmployeeId" InsertVisible="False"
                ReadOnly="True" SortExpression="EmployeeId" Visible="False" />
            <asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" />
            <asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
            <asp:BoundField DataField="Birthdate" HeaderText="Birthdate" SortExpression="Birthdate" />
        </Columns>
    </asp:GridView>

    <!-- This is the button to export CSV! -->
    <asp:Button ID="btnToCSV" runat="server" Text="Export to CSV" OnClick="GetCSV" />

    <asp:SqlDataSource ID="SqlDataSourceLocal" runat="server" 
    ConnectionString="<%$ ConnectionStrings:StackOverflowExamplesConnectionString %>"
        SelectCommand="SELECT * FROM [Employee]"></asp:SqlDataSource>
</asp:Content>

And the code-behind:

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    public void GetCSV(object sender, EventArgs e)
    {
        DataView dv = (DataView)SqlDataSourceLocal.Select(DataSourceSelectArguments.Empty);
        var dt = dv.ToTable();

        var csv = dt.ToCSV();

        WriteToOutput(csv, "export.csv", "text/csv");
    }

    private void WriteToOutput(String csv, String fileName, String mimeType)
    {
        Response.Clear();
        Response.ContentType = mimeType;
        Response.AddHeader("Content-Disposition", String.Format("attachment;filename={0}", fileName));
        Response.Write(csv);
        Response.End();
    }
}

There you go. The only thing not included here is the extension method source, but since I’ve linked to it, you should have no problems getting that into a static class.