在MVC5中的URL中传递变量

Question

I am coding MVC5 and C#.

I have an Index View that simply has a dropdownlist that is populated by a controller - with two table fields (File_Desc & Track_Nmbr). When a user selects a File_Desc from the dropdown, it triggers a javascript to redirect and pass the Track_Nmber as 'keyword' to a view called 'List'. List then shows all items in the database that have the same Track_Nmbr. This part all works as designed.

Where I get lost is the next step. From the LIST view, after users review current items, they are allowed to enter a new item associated to this Track_Nmbr. So, I want the Create View to open and pre-populate the Track_Nmbr field.

I can grab the TRACK_NMBR easy enough from the index view dropdown and pass it to the List View. But how do I pass it again to the Create View? Because I can no longer grab it from the dropdown.

I have been searching and reading, but time is of the essence. I will still continue to find information and try my best to resolve it, but I am at a brick wall. I am very new to MVC5.

I will share all of my code, so that you can see how I have set things up so far. I am looking for the easiest solution to open the Create View and prepopulate the TRACK_NMBR Field.

Code: Index Controller

   public ActionResult Index()
    {

        // Create Drop Down List from Data_Catalog

        {
            List<SelectListItem> testList = db.DATA_CATALOG.Select(x => new SelectListItem { Value = x.TRACK_NMBR.ToString(), Text = x.FILE_DESC, Selected = false }).DistinctBy(p => p.Text).ToList();
            ViewBag.testList = new SelectList(testList, "Value", "Text");
            return View();
        }

        // End Drop Down List

    }

Code: Index View

@section scripts{

<script type="text/javascript">
    $(document).ready(function () {

        $("#testList").on("change", function () {
            window.location.href = "@Url.Action("Create")?keyword=" + $("#testList").val();



        });
    })

</script>
}

@Html.DropDownList("testList", null, "Select File")

Code: List Controller

 public async Task<ActionResult> List(string searchString, int keyword)


    {

            //Pass TRACK_NMBR to LIST via url

            TRACK_NMBR_ViewModel vm = new TRACK_NMBR_ViewModel();
            vm.TRACK_NMBR = keyword;


        var catalogs = from m in db.FILE_RCPTS_LOG
                       select m;
        {
            catalogs = catalogs.Where(s => s.TRACK_NMBR.Equals(keyword));
        }

        return View(await catalogs.ToListAsync());

        }

 public class TRACK_NMBR_ViewModel
    {
        public int TRACK_NMBR { get; set; }
        public string DISPOSITION { get; set; }
        public DateTime DISPOSITION_DT { get; set; }
        public string PROCESSED_BY { get; set; }
        public DateTime DT_PROCESSED { get; set; }
        public string TIMEFRAME_DESC { get; set; }
        public string DTF_FILE_NAME { get; set; }
    }

Code: List View

@section scripts{
<script type="text/javascript">
    function myFunction () {
        window.location.href = "@Url.Action("Create")?keyword=" + $("#testList").val();      
    }

</script>
}

 @Html.ActionLink("Create New", "Create")


@Html.CheckBox("someID", new { @onclick = "myFunction();", htmlAttributes = new { @class = "form-control" } })

As you can see, I placed a checkbox on the view. When user clicks box to add new File_Desc. I want to (once again) send the Keyword (track_nmbr) to the Create View and pre-populate the Track_Nmbr Field. But, my keyword is coming up undefined now. And I can't figure out how to grab it from the url and pass it to the Create View as I did in the Index to List view.

If I can just send the url with the keyword to the Create View, I can get the rest.

Again, pretty new with MVC5 and I am getting a major headache. C# is also new to me, as I come from a VB.net background. However, I found it impossible to find good examples in MVC5 using vb.net, and so I am also addressing the learning curve of c#.

Answer 1

You need to basically pass the track number from your List action method to the view so that it can be used to create the Create link url where you can pass the track number value as a querystring item

Since you are not using a view model, you can use ViewBag to pass this data.

public async Task<ActionResult> List(string searchString, int keyword)
{
  //Your existing code
  ViewBag.Track = keyword;
  return View(await catalogs.ToListAsync());
} 

and now in your view, you can use one of the ActionLink overloads which takes a route value dictionary object.

@Html.ActionLink("Create New", "Create","Home",new { keyword = ViewBag.Track }, null)

This will create an anchor tag with href value which has a querystring item with key keyword and it's value will be whatever value you received in the List action method.

Make sure your Create action method has a parameter to accept the querystring value

public ActionResult Create(int keyword)
{
  // to do : use keyword value
  // to do : return something
}