一旦该数据在 MVC 5 中为 deleted/edited，如何防止将相同的数据添加到列表中并重新使用它？

Question

this is the list of my units

this is how I add units to my list

This is what I want to prevent "Same Data Selected from Downdown again and again.

注意：shopNumber 和 Floor 是两个不同的 table，它们的 ID 用于主要单位表格。

这是我的单元控制器。

    public ActionResult AddUnit() //GET UNITS 
    {

        var floors = _Context.Floor.ToList();
        var shops = _Context.Shop.ToList();
        var viewModel = new UnitFormViewModel
        {

            Floors = floors,
            Shops = shops
        };

        return View("AddUnit",viewModel);
    }

    //POST UNITS

    [HttpPost]
    public ActionResult Save( Unit Unit)
    {

        if (Unit.Id==0)
        _Context.Unit.Add(Unit);

       else
        {
            var unitInDb = _Context.Unit.Single(c => c.Id == Unit.Id);

            unitInDb.Size = Unit.Size;
            unitInDb.floorId = Unit.floorId;
            unitInDb.shopId = Unit.shopId;
        }

        _Context.SaveChanges();

        return RedirectToAction("leaseUnit", "Rent");
    }







    public ActionResult Edit(int id)

    {
        var Unit = _Context.Unit.SingleOrDefault(u => u.Id == id);
        if (Unit == null)
            return HttpNotFound();
        var viewModel = new UnitFormViewModel
        {
            Unit=Unit,
           Floors=_Context.Floor.ToList(),
            Shops = _Context.Shop.ToList()


        };
        return View("EditUnit", viewModel);
    }


    //DELETE A UNIT

    public ActionResult Delete(int id)

    {

        _Context.Unit.Remove(_Context.Unit.Find(id));

        _Context.SaveChanges();

        return RedirectToAction("unitList", "Home");

    }





}

}

这是我在列表中添加一个单元查看代码：

@model mallform.ViewModel.UnitFormViewModel
@{
    ViewBag.Title = "AddUnit";
}

<h2><strong>Add Unit</strong></h2>


@using (Html.BeginForm("Save", "Unit"))

{

    @Html.LabelFor(m => m.Unit.Size)
    @Html.TextBoxFor(m => m.Unit.Size, new { @class = "form-control " })
    @Html.ValidationMessageFor(m => m.Unit.Size)
    <br>
    @Html.LabelFor(m => m.Unit.floorId)
    @Html.DropDownListFor(m => m.Unit.floorId, new SelectList(Model.Floors, "Id", "Name"), "",
        new { @class = "form-control" })
    @Html.ValidationMessageFor(m => m.Unit.floorId)
    <br>
    @Html.LabelFor(m => m.Unit.shopId)
    @Html.DropDownListFor(m => m.Unit.shopId, new SelectList(Model.Shops, "Id", "Name"), "",
        new { @class = "form-control" })
    @Html.ValidationMessageFor(m => m.Unit.shopId)
    <br>
    @Html.HiddenFor(m => m.Unit.Id)

    <br>

    <button type="submit" class="btn btn-primary">Add</button>

}

请告诉我如何防止从下拉菜单中将相同的数据添加到列表中，以及如何在编辑或删除该数据后重新激活该数据的添加。

Answer 1

if(_Context.Unit.Any(u => u.Id != Unit.Id && u.shopId == Unit.shopId))
{
    // return because there already exist a Unit with this shopId
}

一旦该数据在 MVC 5 中为 deleted/edited，如何防止将相同的数据添加到列表中并重新使用它？

how to prevent adding same data to the list from downdown and reuse it once that data is deleted/edited in MVC 5?

c#

crud

duplicates

ef-code-first

asp.net-mvc-5