c# - ViewBag SelectList 中的选定值不起作用

Question

我正在尝试为我的 Controller 中的下拉菜单设置选定值，并通过 ViewBag 将其传递到我的 View 。当我调试时，所有正确的值都被传递给 Controller ​​和 View ，但当它实际呈现在页面上时，未设置所选值。

查看

<tr class="form-group">
<th>
    <label for="CompanyID" class="control-label col-md-9">Company</label>
</th>
<td>
    @Html.DropDownList("CompanyID", (IEnumerable<SelectListItem>)ViewBag.CompanyID, "", new { @class = "required-validation" })
    @Html.ValidationMessageFor(model => model.CompanyID)
</td>

Controller

public ActionResult Edit(int? id) {
if (id == null) {
    return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
var sale = db.SalesOpportunities.Find(id);
if (sale == null) {
    return HttpNotFound();
}

ViewBag.CompanyID = new SelectList(db.Companies, "CompanyID", "Name", sale.CompanyID);

var technicians = db.UserProfiles.Select(t => new {
    ID = t.ID,
    Name = t.FirstName + " " + t.LastName,
}).OrderBy(t => t.Name);

ViewBag.UserID = new SelectList(technicians, "ID", "Name", sale.UserID);

return View(sale);
}

Answer 1

您选择的ViewBag中的字段名称和变量名称不能相同。将其从 ViewBag.CompanyID 更改为 ViewBag.CompanyChoices 之类的内容，它将起作用。