Pass an array to the view using viewbag

Question

I have a code where I used checkbox in order for the user to choose his preferences.

Here is the code in my controller.

[HttpPost]
public ActionResult Selected_Softwares(string[] type){
    var results = db.Softwares_Reports_vw.Where(s => type.Contains(s.software_name)).OrderBy(s=>s.software_name);

//here i tried to pass the parameter to viewbag

ViewBag.type = type;


return PartialView(results);

}

In my view:

<span style="float:right">  <input type="button" style="border: 2px groove #FBF5EF; background-color:ActiveCaption;"
   class="my-button" value="Export Data To Excel" name="back" 
   onclick="@("location.href='" + Url.Action("toExcel_Results2", "Softwares", new { softwares =  ViewBag.type }) + "'")" /> </span> 

And in my controller for the excel reports:

public ActionResult toExcel_Results2(string[] softwares)
    {
        Response.AddHeader("Content-Type", "application/vnd.ms-excel");
        return View(db.Softwares_Reports_vw.Where(s => softwares.Contains(s.software_name)).OrderBy(s=>s.software_name);

    }

But the parameter here had no value. Why? Any help is greatly appreciated.

Answer 1

If you look at the HTML (in the browser F12 tools) for the button labeled "Export Data To Excel" in your Softwares\Selected_Softwares view, you'll see something like this (look at the onclick event):

<input type="button" style="border: 2px groove #FBF5EF; 
    background-color:ActiveCaption;" class="my-button" 
    value="Export Data To Excel" name="back"   
    onclick="location.href='/Softwares/toExcel_Results2?softwares=System.String[]'">

Notice that the object that you put into your ViewBag (a string[]) simply is getting serialized in the HTML as literally "System.String[]". This is because all ASP.NET MVC does is call ToString() on that object. When you call ToString() on a string[], you get the string "System.String[]".

Here's what I would recommend... you seem to be wanting to send some data to your "toExcel_Results2" action. This usually indicates that you want a POST rather than a GET. Here's a fairly simple solution. Just change your Selected_Softwares view to include this:

@using (Html.BeginForm("toExcel_Results2", "Softwares", FormMethod.Post, new { id = "MyForm" }))
{
    <span>
        <input type="button" style="border: 2px groove #FBF5EF; background-color:ActiveCaption;"
               class="my-button" value="Export Data To Excel" name="back"
               onclick="document.getElementById('MyForm').submit();" />

        @for (int i = 0; i < ViewBag.type.Length; i++)
        {
            @Html.Hidden("softwares[" + i.ToString() + "]", (string)ViewBag.type[i]);
        }
    </span>
}

With this, you'll find that your "toExcel_Results2" action is able to receive the full array of strings.