Question

The dropdown list will not select the value I need

 Dictionary<int,int> RowDict = new Dictionary<int, int>();
 for (int i = 1; i < 11; i++)
 {
      RowDict.Add(i, i);
 }
 var rows = new SelectList(RowDict, "Key", "Value", 6);
 ViewBag.Rows = rows;

here is the code in the view:

  <div class="editor-label">
       @Html.LabelFor(m => m.Rows)
  </div>

 <div class="editor-field">
      @Html.DropDownListFor(m => m.Rows, (SelectList)ViewBag.Rows)
      @Html.ValidationMessageFor(m => m.Rows)
 </div>

When I run the code 6 is not selected. Can you see any errors in this code? The first value is selected.

Answer 1

m => m.Rows suggests there is a model involved. It works better if you do the initialization with the rows from the model, not the view bag.

A really quick and dirty initialization like this :

   public class TestModel
   {
      public TestModel()
      {
         Dictionary<int, int> RowDict = new Dictionary<int, int>(); 
         for (int i = 1; i < 11; i++) 
         { 
            RowDict.Add(i, i); 
         }

         this.Rows = new SelectList(RowDict, "Key", "Value");
         this.SelectedId = "6"; // binding to selection works as a String
      }

      public SelectList Rows { get; set; }

      public string SelectedId { get; set; }

   }

And this in the controller where the view is requested :

return View(new TestModel());

And a view starting with something like :

@model <insert_appropriate_anmespace_here>.TestModel

…

@Html.DropDownListFor(m => m.Rows, Model.Rows, Model.SelectedId) 

makes it work. You can adapt this code and initialization the way you want, as long as you remember that models are passed by value to the view, reason why I setup my init in the constructor (every time a TestModel is created, the Select List will get initialized).

Also you can make a mix of viewbag and model and have it to work, I wouldnt recommend it for readability.