Excel file not being downloaded when function is called via ajax method

Niana :

Situation

I am working on an application where I can have a grid with X items, and each item has a print button. Clicking this print button allows me to call an ajax function which passes the ID of the grid item to a controller. I retrieve the relevant data based on that ID and then download it in an excel file. (The retrieving of the specific item is not yet done)

What I have so far

So far, I have the basic code that downloads an excel file, along with my grid .

Problem

The problem I am facing is, if I click the "Print" button...nothing happens, even with a breakpoint in my exporttoexcel functions shows me that the function is entered and I can step thru it and despite no errors, nothing occurs. However, I added random button that called the same function and when i clicked that button, the excel file was downloaded. As a result, I believe the issue has something to do with aJax.

Code

<input type="button" value="Test" onclick="location.href='@Url.Action("ExportToExcel", "Profile")'" />

This is the code which downloads the file. It was a simple button I added.

function ExportToExcel(id) {
    $.ajax({
        type: "POST",
        url: "@Url.Action("ExportToExcel", "Profile")",
        data: { "id": id },
        dataType: "json"

    });
}

This is the function that I want to work, but it does not work and I cannot see what i've got wrong.

Export to Excel Code

public void ExportToExcelx()
{
    var products = new System.Data.DataTable("teste");
    products.Columns.Add("col1", typeof(int));
    products.Columns.Add("col2", typeof(string));

    products.Rows.Add(1, "product 1");
    products.Rows.Add(2, "product 2");
    products.Rows.Add(3, "product 3");
    products.Rows.Add(4, "product 4");
    products.Rows.Add(5, "product 5");
    products.Rows.Add(6, "product 6");
    products.Rows.Add(7, "product 7");


    var grid = new GridView();
    grid.DataSource = products;
    grid.DataBind();

    Response.ClearContent();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", "attachment; filename=MyExcelFile.xls");
    Response.ContentType = "application/ms-excel";

    Response.Charset = "";
    StringWriter sw = new StringWriter();
    HtmlTextWriter htw = new HtmlTextWriter(sw);

    grid.RenderControl(htw);

    //Response.Output.Write(sw.ToString());
    //Response.Flush();
    //Response.End();
    // =============


    //Open a memory stream that you can use to write back to the response
    byte[] byteArray = Encoding.ASCII.GetBytes(sw.ToString());
    MemoryStream s = new MemoryStream(byteArray);
    StreamReader sr = new StreamReader(s, Encoding.ASCII);

    //Write the stream back to the response
    Response.Write(sr.ReadToEnd());
    Response.End();



    //  return View("MyView");
}

Theory

I believe the error is somehow tied in to aJax, I am also creating the button in the controller like this. "<button type='button' class='btn btn-warning' onclick='ExportToExcel(" + c.id + ");'>Print</button>",

Since location.href='@Url.Action works, I was wondering if attempting to redo my dynamic button would solve my issue.

Appreciate any insight that could be offered.

Claudio Valerio :

First of all, I would not use GridView to generate excel. Despite being "easy", it won't generate an actual excel file, but rather a html file with xls extension:

<div>
    <table cellspacing="0" rules="all" border="1" style="border-collapse:collapse;">
        <tr>
            <th scope="col">col1</th><th scope="col">col2</th>
        </tr><tr>
            <td>1</td><td>product 1</td>
        </tr><tr>
            <td>2</td><td>product 2</td>
        </tr><tr>
            <td>3</td><td>product 3</td>
        </tr><tr>
            <td>4</td><td>product 4</td>
        </tr><tr>
            <td>5</td><td>product 5</td>
        </tr><tr>
            <td>6</td><td>product 6</td>
        </tr><tr>
            <td>7</td><td>product 7</td>
        </tr>
    </table>
</div>

This results in a file that when opened will cause this:

that is pretty annoying (and unprofessional). If you're not bounded to old excel version - xls - but can use most recent file format xlsx, I'd rather use DocumentFormat.OpenXml nuget package or other packages/libraries for excel generation. Honestly, DocumentFormat.OpenXml is powerful but a little boring to use, when you have many columns and you just have a flat list of objects to report. If you are using .NET Framework (not Dotnet Core), you can try CsvHelper.Excel nuget package. Usage is pretty straight forward. Your ExportToExcel method will become something like:

public ActionResult ExportToExcel(string id)
{
    // TODO: Replace with correct products retrieving logic using id input
    var products = new [] {
       { col1 = 1, col2 = "product 1" },
       { col1 = 2, col2 = "product 2" },
       { col1 = 3, col2 = "product 3" },
       { col1 = 4, col2 = "product 4" },
       { col1 = 5, col2 = "product 5" },
       { col1 = 6, col2 = "product 6" },
       { col1 = 7, col2 = "product 7" },
       { col1 = 1, col2 = "product 1" },
       { col1 = 1, col2 = "product 1" },
    };

    var ms = new MemoryStream();
    var workbook = new XLWorkbook();
    using (var writer = new CsvWriter(new ExcelSerializer(workbook)))
    {
       writer.WriteRecords(products);
    }
    workbook.SaveAs(ms);
    ms.Flush();
    ms.Seek(0, SeekOrigin.Begin);
    return File(ms, MimeMapping.GetMimeMapping("file.xlsx"), $"MyExcelFile.xlsx");

}

Another package pretty powerful is EPPlus, that allows you to load a DataTable (see this: https://stackoverflow.com/a/53957999/582792).

Coming to the AJAX part, well... I do not think you need it at all: once you set the location to the new ExportToExcel action, it should just download the file. Assuming you are using Bootstrap 3, for each of your item in the collection you can just:

<a href="@Url.Action("ExportToExcel", "Profile", new {id=item.Id})" class="btn btn-info">
<i class="glyphicon glyphicon-download-alt" />
</a>