C# - What is the difference of a Web method and a normal method. Why my block of code works in a normal method and not in a web method

Question

Can someone help me,

I'm trying to do an export to excel module and I have this code for he export:

HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.AddHeader("content-disposition", "attachment; filename=exportTest.xls");
        HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
        HttpContext.Current.Response.Output.Write(excelExport);
        HttpContext.Current.ApplicationInstance.CompleteRequest();

to relate to my question, when I put this block of code to a webmethod invoked by jquery through ajax, it just gives me back the string to export in a message popup, while when I put this block of code into a click method for an asp button control (e.g. ExcelExportButton_Click) it works.

Not working code:

[WebMethod]
    public static void ExportReportsTableToExcel(string ExportReport)
    {
        string excelExport = "a string to export to excel";
        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.AddHeader("content-disposition", "attachment; filename=exportTest.xls");
        HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
        HttpContext.Current.Response.Output.Write(excelExport);
        HttpContext.Current.ApplicationInstance.CompleteRequest();
    }

Working code:

protected void ExportReportButton_Click(object sender, EventArgs e)
    {
        string excelExport = "a string to export to excel";
        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.AddHeader("content-disposition", "attachment; filename=exportTest.xls");
        HttpContext.Current.Response.ContentType = "application/vnd.ms-excel";
        HttpContext.Current.Response.Output.Write(excelExport);
        HttpContext.Current.ApplicationInstance.CompleteRequest();
    }

Please, don't mind the sample string.

Answer 1

Invoking the web method through AJAX won't trigger the file download box. You have a few options:

You could use a JQuery plugin (https://stackoverflow.com/a/9970672/94853). This will create the experience closest to what you are trying to achieve.

Alternatively, you could simply change the window.location to the URL of the web method (https://stackoverflow.com/a/7660817/94853). Depending on how you are passing the ExcelReport string from JavaScript, this may or may not be the simpler route.