使用 ASP.NET MVC 根据 ID 选择名称

Question

I create a new form and I want view name based on id in another table, but the id can't view in the dropdown list:

This is the view:

<div class="form-group">
        <label class="control-label col-md-2">ID Operator</label>
        <div class="col-md-10">
            @Html.DropDownList("idOp", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.idOp, "", new { @class = "text-danger" })
        </div>
    </div>

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

This is the controller :

public ActionResult Create()
{
    ViewBag.idEx = new SelectList(db.tbl_exercises, "idEx");
    ViewBag.idOp = new SelectList(db.tbl_operator, "idOp");
    return View();
} 

Maybe I'm missing the code.

Answer 1

You need choose what field is Name , Value for SelectList like

ViewBag.idEx = new SelectList(tbl_exercises, "Value", "Name");

I made an example base on your code

var tbl_exercises = new List<exercises>
{
                new exercises
                {
                    Name = "Name 1",
                    Value = 10
                },
                new exercises
                {
                    Name = "Name 2",
                    Value = 11
                }
  };

  ViewBag.idEx = new SelectList(tbl_exercises, "Value", "Name");

Answer 2

SelectList is defined as

public SelectList(IEnumerable items, string dataValueField, string dataTextField);

In your controller, try to use

ViewBag.idOp = new SelectList(db.tbl_operator, "idOp","idOp");