How to open a new tab after server's Post Acti

Here's the situation.

I have a save, and a print button :

<input name="btnSubmit" type="submit" value="Save" /> 
<input name="btnSubmit" type="submit" value="Print"/> @*Redirect to Action("Print", "controler")*@

But the print button has to open a new tab. If it was just me, I obviously know I have to save before printing... it would not be an issue. I could use this link with target blank instead :

<a target="_blank" href="@Url.Action("Print", "controler", new { id = Model.id })" type="submit" value="Print" > Print</a>

Easy, but now some users think that the print button should ALSO save the page. Because they don't push save... they just print and the model changes are lost because I can't call the post action in my print link... it's a link.

I thought, at first, that I could make an asynchronous call to a save fonction, but my model is way too big, it requires the post back of it's own action (right ?)

Went through this :

How do I use Target=_blank on a response.redirect?

And i'm not sure if it really help in MVC... right now i'm stuck here :

[HttpPost]
public ActionResult MyForm(string btnSubmit, formModel model)
{
    if (btnSubmit == "Print")
    {
        dbSave(model);
        return RedirectToAction("Print", "controler"); // Won't open new tab... 
    }
}

at first when user click on print button i post my data by ajax request and after successfully done i open a new tab.

Example:

$.ajax({
    url: "@Url.Action("create", "Post")",
    type: "POST",
    contentType: "application/json",
    data: JSON.stringify({ model: model})
}).done(function(result){
window.open('@Url.Action("Print", "controler", new { id = Model.id })', '_blank').focus();
});

You want to write something like your example in http response then you can do something like

  HttpContext.Current.Response.Write( @"<script type='text/javascript' language='javascript'>window.open('page.html','_blank').focus();</script>");

UPDATE

I have added a full flow of a testing project below.

Example:

Model:

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string ProductCode { get; set; }
    public decimal Price { get; set; }
}

Controller:

 public class ProductController : Controller
    {
        // GET: Product
        public ActionResult Index()
        {
            return View();
        }


        // GET: Product/Create
        public ActionResult Save()
        {
            var model = new Product();
            return View(model);
        }

        // POST: Product/Create
        [HttpPost]
        public ActionResult Save(Product model, string saveButton)
        {
            if (ModelState.IsValid)
            {
                //do something 
                return
                    Json(
                        new
                        {
                            redirectTo = Url.Action("Index", "Product", new { Area = "" }),
                            OpenUrl = Url.Action("Print", "Product", new { Area = "" })

                        });
            }
            return View(model);
        }
        public ActionResult Print()
        {
            return View();
        }
}

Save.cshtml:

@model Product

@{
    ViewBag.Title = "Save";
}

<h2>Save</h2>
@Html.Hidden("saveButton","Test")@*Change Test to your value or change it to using JavaScript*@
@using (Html.BeginForm("Save", "Product", new {area = ""}, FormMethod.Post, new {id = "fileForm", name = "fileForm"}))
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>Product</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })

        <div class="form-group">
            @Html.LabelFor(model => model.Name, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Name, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Name, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.ProductCode, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.ProductCode, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.ProductCode, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Price, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Price, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Price, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <button type="button" class="btn btn-primary" id="btnSave">Save</button>
                <button type="button" class="btn btn-default">Print</button>
            </div>
        </div>
    </div>
}

Script:

<script>
        $("#btnSave").click(function() {
            $.ajax({
                url: $("#fileForm").attr('action'),
                type: $("#fileForm").attr('method'),
                beforeSend: function() {
                },
                data: $("#fileForm").serialize() + "&saveButton=" + $("#saveButton").val()
            }).done(function(result) {
                if (result.OpenUrl) {
                    window.open(result.OpenUrl, '_blank');
                }
                if (result.redirectTo) {
                    setTimeout(function() {
                            window.location.href = result.redirectTo;
                        },2000);
                }


            });
        })

    </script>