I want to send free form native query output to excel using a WebGrid - c#-4.0

Question

First I need to explain my problem, I have a native query application where someone types in "Select .... this and that" and the output is currently displayed in a grid that is paginated and I have been asked to add a button that will export the data to excel directly from an untyped datastream. my current code that I've found uses a grid and still doesn't prompt me to download a .xls file for some reason.
[Authorize(Roles = "Portal administrator")]
public void ExportExcel(NativeQueryVM model, int? page, string sort)
{
List<Dictionary<string, object>> result = null;
String vartimedate = DateTime.Now.ToString("yyyy-dd-M--HH-mm-ss");
try
{
var user = Membership.GetUser();
var grid = new System.Web.UI.WebControls.GridView();
if (page == null && sort == null)
{
if (model.QueryText.ToUpper().StartsWith("SELECT"))
{
UserQueryInput queryinput = new UserQueryInput();
queryinput.DatabaseId = model.selectedDatabase;
queryinput.QueryText = model.QueryText;
result = lookupProvider.GetSetNativeQuery((Guid)user.ProviderUserKey, user.UserName, queryinput, "Set");
model.QueryResultData = result;
ViewBag.SubmitType = "Select";
CreateDynamicResult(model.QueryResultData);
if (model == null || model.QueryResultData.Count == 0)
{
ViewBag.ResultMessage = "No Results Found";
}
else
{
WebGrid wd = new WebGrid(source: ViewBag.DynamicResult, canPage: false, canSort: false );
string griddata = wd.GetHtml().ToString();
string attachment = "attachment; filename=NativeQuery" + vartimedate + ".xls";
Response.ClearContent();
Response.AddHeader("content-disposition", attachment);
Response.ContentType = "application/excel";
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
Response.Write(griddata);
Response.End();
}
}
}
else
{ //This part should come when page or sort is not null for Select. Should not be executed other than SELECT
result = lookupProvider.GetSetNativeQuery((Guid)user.ProviderUserKey, user.UserName, null, "Get");
model.QueryResultData = result;
ViewBag.SubmitType = "Select";
CreateDynamicResult(model.QueryResultData);
if (model == null || model.QueryResultData.Count == 0)
{
ViewBag.ResultMessage = "No Results Found";
}
else
{
}
}
}
catch (Exception ex)
{
logger.Log(new LogMessage()
.ForMethod("SubmitQuery")
.WithContext(Environment.MachineName)
.WithException(ex)
.WithDescription("An error occurred while submiting query to get result"));
}
}

Answer 1

Hi all that answered this problem, and I've found the answer and issues reside outside of the code that I've entered into the question. Jquery was intercepting the output of my file stream and on the other hand, if the button was created with runat=server the model is out of scope and the main part of the solution involved saving the model to a session and pulling it back in.
Thanks for your assistance all...

Answer 2

How are you calling this void function? The return paths include setting a ViewBag property with an error message along with modifying the response. It smells of bad design.
I'd create a hyperlink that links to a #Url.Action for something like this. Note that you'd need to return a FileContentResult with the data UTF8-encoded rather than modifying the Response directly:
public async Task<ActionResult> Test()
{
WebGrid wd = new WebGrid(source: ViewBag.DynamicResult, canPage: false, canSort: false );
string griddata = wd.GetHtml().ToString();
string attachment = "attachment; filename=NativeQuery" + vartimedate + ".xls";
Response.ClearContent();
Response.AddHeader("content-disposition", attachment);
Response.ContentType = "application/excel";
byte[] buffer = System.Text.UTF8Encoding.UTF8.GetBytes(griddata);
return File(buffer, "application/octet-stream");
}