C# ASP.NET MVC使用DropDownList编辑视图模型

在编辑操作中检索DropDownList控件的正确值时遇到问题

客户型号：

    public class Customer
{
    public int CustId { get; set; }
    public string CustDisplayName { get; set; }
    public string CustFirstName { get; set; }
    public string CustLastName { get; set; }
    public string CustCompanyName { get; set; }
    public string CustAddress { get; set; }
    public string CustPhoneNumber { get; set; }
    public string CustMobileNumber { get; set; }
    public string CustEmailAddress { get; set; }

    public int StId { get; set; }
    public State State { get; set; }
}

    public class State
{
    public int StId { get; set; }
    public string StAbbr { get; set; }

    public List<Customer> Customers { get; set; }
}

    public class Manufacturer
{
    public int MfrId { get; set; }
    public string MfrCompanyName { get; set; }
    public string MfrWebsiteDomainName { get; set; }
}

public class CustomerController : Controller
{
    private WebAppDbContext _context;

    public CustomerController(WebAppDbContext context)
    {
        _context = context;
    }

    // GET: /<Customer>/
    public IActionResult Index()
    {
        return View(_context.Customers.ToList());
    }

    public ActionResult Create()
    {
        var states = _context.States.ToList();
        var viewModel = new CustomerFormViewModel
        {
            States = states
        };

        return View(viewModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(CustomerFormViewModel vm)
    {
        if (ModelState.IsValid)
        {
            var customer = new Customer();
            {
                customer.CustDisplayName = vm.CustDisplayName;
                customer.CustFirstName = vm.CustFirstName;
                customer.CustLastName = vm.CustLastName;
                customer.CustCompanyName = vm.CustCompanyName;
                customer.CustAddress = vm.CustAddress;
                customer.CustPhoneNumber = vm.CustPhoneNumber;
                customer.CustMobileNumber = vm.CustMobileNumber;
                customer.CustEmailAddress = vm.CustEmailAddress;
                customer.StId = vm.StId;
            }
            _context.Customers.Add(customer);
            _context.SaveChanges();
            return RedirectToAction("Index");
        }

        else
        {
            vm.States = _context.States.ToList();
            return View(vm);
        }
    }

    public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var customervm = new CustomerFormViewModel();
        {
            Customer customer = _context.Customers.SingleOrDefault(c => c.CustId == id);
            if (customer == null)
            {
                return NotFound();
            }

            customervm.CustId = customer.CustId;
            customervm.CustDisplayName = customer.CustDisplayName;
            customervm.CustFirstName = customer.CustFirstName;
            customervm.CustLastName = customer.CustLastName;
            customervm.CustCompanyName = customer.CustCompanyName;
            customervm.CustAddress = customer.CustAddress;
            customervm.CustPhoneNumber = customer.CustPhoneNumber;
            customervm.CustMobileNumber = customer.CustMobileNumber;
            customervm.CustEmailAddress = customer.CustEmailAddress;
            customervm.StId = customer.StId;
        }
        return View(customervm);
    }
}

    <div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

<div class="form-group">
    <button type="submit" class="btn btn-primary">Submit</button>
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

@Html.HiddenFor(c => c.CustId)

<div class="form-group">
    <button type="submit" class="btn btn-primary">Update</button>
</div>

状态模型：

    public class Customer
{
    public int CustId { get; set; }
    public string CustDisplayName { get; set; }
    public string CustFirstName { get; set; }
    public string CustLastName { get; set; }
    public string CustCompanyName { get; set; }
    public string CustAddress { get; set; }
    public string CustPhoneNumber { get; set; }
    public string CustMobileNumber { get; set; }
    public string CustEmailAddress { get; set; }

    public int StId { get; set; }
    public State State { get; set; }
}

    public class State
{
    public int StId { get; set; }
    public string StAbbr { get; set; }

    public List<Customer> Customers { get; set; }
}

    public class Manufacturer
{
    public int MfrId { get; set; }
    public string MfrCompanyName { get; set; }
    public string MfrWebsiteDomainName { get; set; }
}

public class CustomerController : Controller
{
    private WebAppDbContext _context;

    public CustomerController(WebAppDbContext context)
    {
        _context = context;
    }

    // GET: /<Customer>/
    public IActionResult Index()
    {
        return View(_context.Customers.ToList());
    }

    public ActionResult Create()
    {
        var states = _context.States.ToList();
        var viewModel = new CustomerFormViewModel
        {
            States = states
        };

        return View(viewModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(CustomerFormViewModel vm)
    {
        if (ModelState.IsValid)
        {
            var customer = new Customer();
            {
                customer.CustDisplayName = vm.CustDisplayName;
                customer.CustFirstName = vm.CustFirstName;
                customer.CustLastName = vm.CustLastName;
                customer.CustCompanyName = vm.CustCompanyName;
                customer.CustAddress = vm.CustAddress;
                customer.CustPhoneNumber = vm.CustPhoneNumber;
                customer.CustMobileNumber = vm.CustMobileNumber;
                customer.CustEmailAddress = vm.CustEmailAddress;
                customer.StId = vm.StId;
            }
            _context.Customers.Add(customer);
            _context.SaveChanges();
            return RedirectToAction("Index");
        }

        else
        {
            vm.States = _context.States.ToList();
            return View(vm);
        }
    }

    public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var customervm = new CustomerFormViewModel();
        {
            Customer customer = _context.Customers.SingleOrDefault(c => c.CustId == id);
            if (customer == null)
            {
                return NotFound();
            }

            customervm.CustId = customer.CustId;
            customervm.CustDisplayName = customer.CustDisplayName;
            customervm.CustFirstName = customer.CustFirstName;
            customervm.CustLastName = customer.CustLastName;
            customervm.CustCompanyName = customer.CustCompanyName;
            customervm.CustAddress = customer.CustAddress;
            customervm.CustPhoneNumber = customer.CustPhoneNumber;
            customervm.CustMobileNumber = customer.CustMobileNumber;
            customervm.CustEmailAddress = customer.CustEmailAddress;
            customervm.StId = customer.StId;
        }
        return View(customervm);
    }
}

    <div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

<div class="form-group">
    <button type="submit" class="btn btn-primary">Submit</button>
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

@Html.HiddenFor(c => c.CustId)

<div class="form-group">
    <button type="submit" class="btn btn-primary">Update</button>
</div>

CustomPerformViewModel

public class CustomerFormViewModel
{
    public int CustId { get; set; }

    [Required(ErrorMessage = "Display Name is required!")]
    [Display(Name = "Display Name")]
    [StringLength(100)]
    public string CustDisplayName { get; set; }

    [Display(Name = "First Name")]
    [StringLength(50)]
    public string CustFirstName { get; set; }

    [Display(Name = "Last Name")]
    [StringLength(50)]
    public string CustLastName { get; set; }

    [Display(Name = "Company Name")]
    [StringLength(50)]
    public string CustCompanyName { get; set; }

    [Display(Name = "Phone Number")]
    [DataType(DataType.PhoneNumber)]
    [StringLength(12)]
    [RegularExpression(@"((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}", ErrorMessage = "Invalid Phone Number format!")]
    public string CustPhoneNumber { get; set; }

    [Display(Name = "Mobile Number")]
    [DataType(DataType.PhoneNumber)]
    [StringLength(12)]
    [RegularExpression(@"((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}", ErrorMessage = "Invalid  Number!")]
    public string CustMobileNumber { get; set; }

    [Display(Name = "Email Address")]
    [DataType(DataType.EmailAddress)]
    [StringLength(320)]
    public string CustEmailAddress { get; set; }

    [Required(ErrorMessage = "Address is required!")]
    [Display(Name = "Address")]
    [StringLength(100)]
    public string CustAddress { get; set; }

    [Required(ErrorMessage = "State is required!")]
    [Display(Name = "State")]
    public int StId { get; set; }

    public IEnumerable<State> States { get; set; }
}

公共类CustomPerformViewModel
{
public int CustId{get；set；}
[必需（ErrorMessage=“需要显示名称！”）]
[显示（Name=“显示名称”）]
[长度（100）]
公共字符串CustDisplayName{get；set；}
[显示（Name=“First Name”）]
[长度（50）]
公共字符串CustFirstName{get；set；}
[显示（Name=“Last Name”）]
[长度（50）]
公共字符串CustLastName{get；set；}
[显示（名称=“公司名称”）]
[长度（50）]
公共字符串CustCompanyName{get；set；}
[显示（Name=“电话号码”）]
[数据类型（数据类型.电话号码）]
[条次建议修正案（12）]
[RegularExpression（@“（\（\d{3}\）？）|（\d{3}-）？\d{3}-\d{4}”，ErrorMessage=“电话号码格式无效！”）
公共字符串CustPhoneNumber{get；set；}
[显示（Name=“手机号码”）]
[数据类型（数据类型.电话号码）]
[条次建议修正案（12）]
[RegularExpression（@“（\（\d{3}\）？）|（\d{3}-）？\d{3}-\d{4}”，ErrorMessage=“无效数字！”）
公共字符串CustMobileNumber{get；set；}
[显示（Name=“电子邮件地址”）]
[数据类型（数据类型.电子邮件地址）]
[长度（320）]
公共字符串CustEmailAddress{get；set；}
[必需（ErrorMessage=“地址是必需的！”）]
[显示（Name=“Address”）]
[长度（100）]
公共字符串地址{get；set；}
[必需（ErrorMessage=“状态是必需的！”）]
[显示（Name=“State”）]
公共int StId{get；set；}
公共IEnumerable状态{get；set；}
}

客户控制器：

    public class Customer
{
    public int CustId { get; set; }
    public string CustDisplayName { get; set; }
    public string CustFirstName { get; set; }
    public string CustLastName { get; set; }
    public string CustCompanyName { get; set; }
    public string CustAddress { get; set; }
    public string CustPhoneNumber { get; set; }
    public string CustMobileNumber { get; set; }
    public string CustEmailAddress { get; set; }

    public int StId { get; set; }
    public State State { get; set; }
}

    public class State
{
    public int StId { get; set; }
    public string StAbbr { get; set; }

    public List<Customer> Customers { get; set; }
}

    public class Manufacturer
{
    public int MfrId { get; set; }
    public string MfrCompanyName { get; set; }
    public string MfrWebsiteDomainName { get; set; }
}

public class CustomerController : Controller
{
    private WebAppDbContext _context;

    public CustomerController(WebAppDbContext context)
    {
        _context = context;
    }

    // GET: /<Customer>/
    public IActionResult Index()
    {
        return View(_context.Customers.ToList());
    }

    public ActionResult Create()
    {
        var states = _context.States.ToList();
        var viewModel = new CustomerFormViewModel
        {
            States = states
        };

        return View(viewModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(CustomerFormViewModel vm)
    {
        if (ModelState.IsValid)
        {
            var customer = new Customer();
            {
                customer.CustDisplayName = vm.CustDisplayName;
                customer.CustFirstName = vm.CustFirstName;
                customer.CustLastName = vm.CustLastName;
                customer.CustCompanyName = vm.CustCompanyName;
                customer.CustAddress = vm.CustAddress;
                customer.CustPhoneNumber = vm.CustPhoneNumber;
                customer.CustMobileNumber = vm.CustMobileNumber;
                customer.CustEmailAddress = vm.CustEmailAddress;
                customer.StId = vm.StId;
            }
            _context.Customers.Add(customer);
            _context.SaveChanges();
            return RedirectToAction("Index");
        }

        else
        {
            vm.States = _context.States.ToList();
            return View(vm);
        }
    }

    public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var customervm = new CustomerFormViewModel();
        {
            Customer customer = _context.Customers.SingleOrDefault(c => c.CustId == id);
            if (customer == null)
            {
                return NotFound();
            }

            customervm.CustId = customer.CustId;
            customervm.CustDisplayName = customer.CustDisplayName;
            customervm.CustFirstName = customer.CustFirstName;
            customervm.CustLastName = customer.CustLastName;
            customervm.CustCompanyName = customer.CustCompanyName;
            customervm.CustAddress = customer.CustAddress;
            customervm.CustPhoneNumber = customer.CustPhoneNumber;
            customervm.CustMobileNumber = customer.CustMobileNumber;
            customervm.CustEmailAddress = customer.CustEmailAddress;
            customervm.StId = customer.StId;
        }
        return View(customervm);
    }
}

    <div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

<div class="form-group">
    <button type="submit" class="btn btn-primary">Submit</button>
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

@Html.HiddenFor(c => c.CustId)

<div class="form-group">
    <button type="submit" class="btn btn-primary">Update</button>
</div>

公共类CustomerController:控制器
{
私有WebAppDbContext _context；
公共CustomerController（WebAppDbContext上下文）
{
_上下文=上下文；
}
//获取：//
公共IActionResult索引（）
{
返回视图（_context.Customers.ToList（））；
}
公共操作结果创建（）
{
var states=_context.states.ToList（）；
var viewModel=新的CustomPerformViewModel
{
状态=状态
};
返回视图（viewModel）；
}
[HttpPost]
[ValidateAntiForgeryToken]
公共操作结果创建（CustomPerformViewModel虚拟机）
{
if（ModelState.IsValid）
{
var customer=新客户（）；
{
customer.CustDisplayName=vm.CustDisplayName；
customer.CustFirstName=vm.CustFirstName；
customer.CustLastName=vm.CustLastName；
customer.CustCompanyName=vm.CustCompanyName；
customer.CustAddress=vm.CustAddress；
customer.CustPhoneNumber=vm.CustPhoneNumber；
customer.CustMobileNumber=vm.CustMobileNumber；
customer.CustEmailAddress=vm.CustEmailAddress；
customer.StId=vm.StId；
}
_context.Customers.Add（客户）；
_SaveChanges（）；
返回操作（“索引”）；
}
其他的
{
vm.States=_context.States.ToList（）；
返回视图（vm）；
}
}
公共行动结果编辑（int？id）
{
if（id==null）
{
返回NotFound（）；
}
var customervm=新的CustomerFormViewModel（）；
{
Customer=\u context.Customers.SingleOrDefault（c=>c.CustId==id）；
如果（客户==null）
{
返回NotFound（）；
}
customervm.CustId=customer.CustId；
customervm.CustDisplayName=customer.CustDisplayName；
customervm.CustFirstName=customer.CustFirstName；
customervm.CustLastName=customer.CustLastName；
customervm.CustCompanyName=customer.CustCompanyName；
customervm.CustAddress=customer.CustAddress；
customervm.CustPhoneNumber=customer.CustPhoneNumber；
customervm.CustMobileNumber=customer.CustMobileNumber；
customervm.custmailaddress=customer.custmailaddress；
customervm.StId=customer.StId；
}
返回视图（customervm）；
}
}

创建视图：

    public class Customer
{
    public int CustId { get; set; }
    public string CustDisplayName { get; set; }
    public string CustFirstName { get; set; }
    public string CustLastName { get; set; }
    public string CustCompanyName { get; set; }
    public string CustAddress { get; set; }
    public string CustPhoneNumber { get; set; }
    public string CustMobileNumber { get; set; }
    public string CustEmailAddress { get; set; }

    public int StId { get; set; }
    public State State { get; set; }
}

    public class State
{
    public int StId { get; set; }
    public string StAbbr { get; set; }

    public List<Customer> Customers { get; set; }
}

    public class Manufacturer
{
    public int MfrId { get; set; }
    public string MfrCompanyName { get; set; }
    public string MfrWebsiteDomainName { get; set; }
}

public class CustomerController : Controller
{
    private WebAppDbContext _context;

    public CustomerController(WebAppDbContext context)
    {
        _context = context;
    }

    // GET: /<Customer>/
    public IActionResult Index()
    {
        return View(_context.Customers.ToList());
    }

    public ActionResult Create()
    {
        var states = _context.States.ToList();
        var viewModel = new CustomerFormViewModel
        {
            States = states
        };

        return View(viewModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(CustomerFormViewModel vm)
    {
        if (ModelState.IsValid)
        {
            var customer = new Customer();
            {
                customer.CustDisplayName = vm.CustDisplayName;
                customer.CustFirstName = vm.CustFirstName;
                customer.CustLastName = vm.CustLastName;
                customer.CustCompanyName = vm.CustCompanyName;
                customer.CustAddress = vm.CustAddress;
                customer.CustPhoneNumber = vm.CustPhoneNumber;
                customer.CustMobileNumber = vm.CustMobileNumber;
                customer.CustEmailAddress = vm.CustEmailAddress;
                customer.StId = vm.StId;
            }
            _context.Customers.Add(customer);
            _context.SaveChanges();
            return RedirectToAction("Index");
        }

        else
        {
            vm.States = _context.States.ToList();
            return View(vm);
        }
    }

    public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var customervm = new CustomerFormViewModel();
        {
            Customer customer = _context.Customers.SingleOrDefault(c => c.CustId == id);
            if (customer == null)
            {
                return NotFound();
            }

            customervm.CustId = customer.CustId;
            customervm.CustDisplayName = customer.CustDisplayName;
            customervm.CustFirstName = customer.CustFirstName;
            customervm.CustLastName = customer.CustLastName;
            customervm.CustCompanyName = customer.CustCompanyName;
            customervm.CustAddress = customer.CustAddress;
            customervm.CustPhoneNumber = customer.CustPhoneNumber;
            customervm.CustMobileNumber = customer.CustMobileNumber;
            customervm.CustEmailAddress = customer.CustEmailAddress;
            customervm.StId = customer.StId;
        }
        return View(customervm);
    }
}

    <div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

<div class="form-group">
    <button type="submit" class="btn btn-primary">Submit</button>
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

@Html.HiddenFor(c => c.CustId)

<div class="form-group">
    <button type="submit" class="btn btn-primary">Update</button>
</div>

@LabelFor（c=>c.CustDisplayName）
@TextBoxFor（c=>c.CustDisplayName，新的{@class=“formcontrol”}）
@Html.ValidationMessageFor（c=>c.CustDisplayName）
@LabelFor（c=>c.CustFirstName）
@TextBoxFor（c=>c.CustFirstName，新的{@class=“form control”}）
@LabelFor（c=>c.CustLastName）
@TextBoxFor（c=>c.CustLastName，new{@class=“form control”}）
@LabelFor（c=>c.CustCompanyName）
@TextBoxFor（c=>c.CustCompanyName，新的{@class=“form control”}）
@LabelFor（c=>c.CustAddress）
@TextBoxFor（c=>c.CustAddress，新的{@class=“form control”}）
@Html.ValidationMessageFor（c=>c.CustAddress）
@LabelFor（c=>c.CustPhoneNumber）
@TextBoxFor（c=>c.CustPhoneNumber，新的{@class=“form control”}）
@Html.ValidationMessageFor（c=>c.CustPhoneNumber）
@LabelFor（c=>c.CustMobileNumber）
@TextBoxFor（c=>c.CustMobileNumber，新的{@class=“form control”}）
@Html.ValidationMessageFor（c=>c.CustMobileNumber）
@LabelFor（c=>c.CustEmailAddress）
@TextBoxFor（c=>c.CustEmailAddress，新的{@class=“form control”}）
@Html.ValidationMessageFor（c=>c.CustEmailAddress）
@LabelFor（s=>s.StId）
@DropDownListFor（s=>s.StId，new SelectList（Model.States，“StId”，“stirr”），“”，new{@class=“form control”}）
@Html.ValidationMessageFor（s=>s.StId）
提交

编辑视图：

    public class Customer
{
    public int CustId { get; set; }
    public string CustDisplayName { get; set; }
    public string CustFirstName { get; set; }
    public string CustLastName { get; set; }
    public string CustCompanyName { get; set; }
    public string CustAddress { get; set; }
    public string CustPhoneNumber { get; set; }
    public string CustMobileNumber { get; set; }
    public string CustEmailAddress { get; set; }

    public int StId { get; set; }
    public State State { get; set; }
}

    public class State
{
    public int StId { get; set; }
    public string StAbbr { get; set; }

    public List<Customer> Customers { get; set; }
}

    public class Manufacturer
{
    public int MfrId { get; set; }
    public string MfrCompanyName { get; set; }
    public string MfrWebsiteDomainName { get; set; }
}

public class CustomerController : Controller
{
    private WebAppDbContext _context;

    public CustomerController(WebAppDbContext context)
    {
        _context = context;
    }

    // GET: /<Customer>/
    public IActionResult Index()
    {
        return View(_context.Customers.ToList());
    }

    public ActionResult Create()
    {
        var states = _context.States.ToList();
        var viewModel = new CustomerFormViewModel
        {
            States = states
        };

        return View(viewModel);
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Create(CustomerFormViewModel vm)
    {
        if (ModelState.IsValid)
        {
            var customer = new Customer();
            {
                customer.CustDisplayName = vm.CustDisplayName;
                customer.CustFirstName = vm.CustFirstName;
                customer.CustLastName = vm.CustLastName;
                customer.CustCompanyName = vm.CustCompanyName;
                customer.CustAddress = vm.CustAddress;
                customer.CustPhoneNumber = vm.CustPhoneNumber;
                customer.CustMobileNumber = vm.CustMobileNumber;
                customer.CustEmailAddress = vm.CustEmailAddress;
                customer.StId = vm.StId;
            }
            _context.Customers.Add(customer);
            _context.SaveChanges();
            return RedirectToAction("Index");
        }

        else
        {
            vm.States = _context.States.ToList();
            return View(vm);
        }
    }

    public ActionResult Edit(int? id)
    {
        if (id == null)
        {
            return NotFound();
        }

        var customervm = new CustomerFormViewModel();
        {
            Customer customer = _context.Customers.SingleOrDefault(c => c.CustId == id);
            if (customer == null)
            {
                return NotFound();
            }

            customervm.CustId = customer.CustId;
            customervm.CustDisplayName = customer.CustDisplayName;
            customervm.CustFirstName = customer.CustFirstName;
            customervm.CustLastName = customer.CustLastName;
            customervm.CustCompanyName = customer.CustCompanyName;
            customervm.CustAddress = customer.CustAddress;
            customervm.CustPhoneNumber = customer.CustPhoneNumber;
            customervm.CustMobileNumber = customer.CustMobileNumber;
            customervm.CustEmailAddress = customer.CustEmailAddress;
            customervm.StId = customer.StId;
        }
        return View(customervm);
    }
}

    <div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

<div class="form-group">
    <button type="submit" class="btn btn-primary">Submit</button>
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustDisplayName)
    @Html.TextBoxFor(c => c.CustDisplayName, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustDisplayName)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustFirstName)
    @Html.TextBoxFor(c => c.CustFirstName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustLastName)
    @Html.TextBoxFor(c => c.CustLastName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustCompanyName)
    @Html.TextBoxFor(c => c.CustCompanyName, new { @class = "form-control" })
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustAddress)
    @Html.TextBoxFor(c => c.CustAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustAddress)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustPhoneNumber)
    @Html.TextBoxFor(c => c.CustPhoneNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustPhoneNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustMobileNumber)
    @Html.TextBoxFor(c => c.CustMobileNumber, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustMobileNumber)
</div>

<div class="form-group">
    @Html.LabelFor(c => c.CustEmailAddress)
    @Html.TextBoxFor(c => c.CustEmailAddress, new { @class = "form-control" })
    @Html.ValidationMessageFor(c => c.CustEmailAddress)
</div>

<div class="form-group">
    @Html.LabelFor(s => s.StId)
    @Html.DropDownListFor(s => s.StId, new SelectList(Model.States, "StId", "StAbbr"), "", new { @class = "form-control" })
    @Html.ValidationMessageFor(s => s.StId)
</div>

@Html.HiddenFor(c => c.CustId)

<div class="form-group">
    <button type="submit" class="btn btn-primary">Update</button>
</div>

@LabelFor（c=>c.custdepra