MVC5 EF实体显然正在保存，但在检索时为null

我有一个Account类，其中包含Payments清单，其中包含Pending ， Sold或Refunded的Products列表。

选择要付费的Products ，我可以将它们添加到Payment对象中，然后将整个对象保存到Account 。

但是，当我在Pay操作中检索帐户时， Account.Payments为空。

这是AddProduct操作：

 public ActionResult AddProduct(List products) { //var acc = Account.FetchAccountFromIdentity(User.Identity.GetUserName()); var username = User.Identity.GetUserName(); var acc = db.Accounts.First(u => u.EmailAddress == username); var payment = new Payment(); foreach (var product in products) { if (product.IsSelected) { var tempProduct = db.Products.Find(product.ProductID); payment.Products.Add(tempProduct); payment.PaymentStatus = enPaymentStatus.Pending; payment.Gross += tempProduct.Price; payment.Vat += tempProduct.Price * 0.2; payment.Net += payment.Gross - payment.Vat; } } payment.AccountID = acc; if (acc.Payments == null) acc.Payments = new List(); acc.Payments.Add(payment); db.SaveChanges(); return RedirectToAction("Pay", "Products", new {id = acc.AccountID} ); } 

acc.Payments已正确填充任何相关付款。

然后Pay行动：

  public ActionResult Pay(int? id) { var acc = db.Accounts.Find(id); var data = new AccountPaymentView { Account = acc, Payment = acc.Payments.First(p => p.PaymentStatus == enPaymentStatus.Pending) }; return View(data); } 

acc.Payments现在为空！？

知道我一定做错了吗？

使用帐户类立即编辑 ：

  public class Account { [Key] [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int AccountID { get; set; } [Display(Name = "Title")] public string Salutation { get; set; } [Required] [Display(Name = "First Name")] public string FirstName { get; set; } [Required] [Display(Name = "Last Name")] public string LastName { get; set; } [Required] [DataType(DataType.Password)] [Display(Name = "Password")] public string Password { get; set; } [Required] [DataType(DataType.Password)] [Compare("Password", ErrorMessage = "Passwords do not match. Please try again.")] [Display(Name = "Confirm Password")] public string ConfirmPass { get; set; } [Required] [DataType(DataType.EmailAddress)] [Display(Name = "Email Address")] public string EmailAddress { get; set; } public virtual ICollection
 Addresses { get; set; } public virtual ICollection Payments { get; set; } public DateTime CreatedOn { get; set; } public virtual ICollection VistsList { get; set; } public bool IsDeleted { get; set; } public enAccountType AccountType { get; set; } } 

编辑2这是DBContext上的OnModelCreating方法（删除了不相关的部分）。 我找不到一些明显的东西吗？

 protected override void OnModelCreating(DbModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); modelBuilder.Properties() .Configure(c => c.HasColumnType("datetime2")); modelBuilder.Entity().HasOptional(x => x.Addresses).WithMany(); modelBuilder.Entity().HasOptional(x => x.Payments).WithMany(); modelBuilder.Entity().HasOptional(x => x.Products).WithMany(); modelBuilder.Entity().HasOptional(x => x.AccountID); modelBuilder.Entity().HasKey(x => x.PaymentID); } 

编辑3检出Account.FetchAccountFromIdentity（），它确实打开了一个新的上下文。 所以现在已经删除了，现在我在AddProduct方法中使用了一个上下文（上面更新的代码）。

现在我在保存时遇到以下错误！

 An object of type 'System.Collections.Generic.List`1[[PPPv2.Models.Payment, PPPv2, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]' cannot be set or removed from the Value property of an EntityReference of type 'PPPv2.Models.Payment'. 

我尝试在OnModelCreating方法中强制PK关系，但它似乎没有帮助。

为清楚起见，这是付款类：

 public class Payment { [Key] [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int PaymentID { get; set; } public virtual Account AccountID { get; set; } public virtual ICollection Products { get; set; } public double Gross { get; set; } public double Net { get; set; } public double Vat { get; set; } public string TransactionCode { get; set; } public enPaymentStatus PaymentStatus { get; set; } public bool IsDeleted { get; set; } public DateTime PaidOn { get; set; } public Payment() { Products = new List(); Gross = 0.0; Net = 0.0; Vat = 0.0; IsDeleted = false; PaidOn = new DateTime(2000, 1, 1, 0, 0,0); } } 

编辑4根据要求，这是产品型号：

 public class Product { [Key] [DatabaseGenerated(DatabaseGeneratedOption.Identity)] public int ProductID { get; set; } public string Name { get; set; } public string Description { get; set; } [DataType(DataType.Currency)] [DisplayFormat(DataFormatString = "£{0:#,###0.00}")] public double Price { get; set; } [DataType(DataType.Currency)] [Display(Name = "Total Estimated Legal Cost")] [DisplayFormat(DataFormatString = "£{0:#,###0.00}")] public double EstimatedTotalLegalCost { get; set; } public virtual ICollection Overviews { get; set; } public virtual ICollection Processes { get; set; } public DateTime CreatedOn { get; set; } public DateTime LastUpdated { get; set; } public bool IsSelected { get; set; } public bool IsDeleted { get; set; } } 

Answer 1

如果查看entity framework生成的表，您将看到其中只有三个。 根据您的数据模型，应该存在将Account和Payment对象映射到彼此的联结表（对于Payment和Product ，并且您可能需要对您拥有的其他集合执行相同的操作）。

您无法将Products List转换为单个Products的例外情况是因为您的数据模型表明Products是一个集合，但数据库表实际上是将它存储为外键（即单个实体）之间的关系Payment和Product 。

如果我将OnModelCreating方法中的代码更改为以下内容，则AddProducts方法将按预期工作。

 protected override void OnModelCreating(DbModelBuilder modelBuilder) { base.OnModelCreating(modelBuilder); modelBuilder.Properties().Configure(c => c.HasColumnType("datetime2")); modelBuilder.Entity().HasMany(x => x.Addresses) .WithMany().Map(t => t.ToTable("AccountAddresses")); modelBuilder.Entity().HasMany(x => x.Payments) .WithMany().Map(t => t.ToTable("AccountPayments")); modelBuilder.Entity().HasMany(x => x.Products) .WithMany().Map(t => t.ToTable("PaymentProducts")); modelBuilder.Entity().HasOptional(x => x.AccountID); modelBuilder.Entity().HasKey(x => x.PaymentID); } 

改变来自以下代码：

 modelBuilder.Entity().HasOptional(x => x.Products).WithMany(); 

至：

 modelBuilder.Entity().HasMany(x => x.Products).WithMany().Map(t => t.ToTable("PaymentProducts")); 

这样做会指示entity framework创建允许Payment持有Products集合的联结表。

Answer 2

创建付款时，您应将其直接保存到数据库中。 我不认为将它添加到您的帐户对象会起作用，因为它是一个尚未被EF跟踪的实体。

 public ActionResult AddProduct(List products) { //var acc = Account.FetchAccountFromIdentity(User.Identity.GetUserName()); var username = User.Identity.GetUserName(); var acc = db.Accounts.First(u => u.EmailAddress == username); var payment = new Payment(); foreach (var product in products) { if (product.IsSelected) { var tempProduct = db.Products.Find(product.ProductID); payment.Products.Add(tempProduct); payment.PaymentStatus = enPaymentStatus.Pending; payment.Gross += tempProduct.Price; payment.Vat += tempProduct.Price * 0.2; payment.Net += payment.Gross - payment.Vat; } } payment.AccountID = acc.AccountID; db.Payments.Add(payment); db.SaveChanges(); return RedirectToAction("Pay", "Products", new {id = acc.AccountID} ); }