I have a Gridview that reads the DataSource from an EntityDataSrouce. Now I want to convert the EntityDatasource of the gridview to DataTable so I can export it the Gridview as an Excel file.
You do not need to convert it to DataTable
just to export. You can do it by gridview self.
Look at this link: http://mattberseth.com/blog/2007/04/export_gridview_to_excel_1.html
In this article, the author uses a utility class that export it to .xls file, so, you can download it, add on your project and use like the sample.