c# - MVC5 EF 实体显然在保存，但在检索时为空

Question

我有一个 Account 类，其中包含一个 Payments 列表，其中包含一个 Products 列表，该列表是 Pending、Sold 或 Refunded。

选择要付费的产品时，我可以将它们添加到付款对象中，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<Product> 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<Payment>();
    acc.Payments.Add(payment);
    db.SaveChanges();

    return RedirectToAction("Pay", "Products", new {id = acc.AccountID} );
}

acc.Payments 此时已正确填充任何相关付款。

然后是 Pay 操作:

    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!？

知道我一定做错了什么吗？

编辑现在有了帐户类别:

    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<Address> Addresses { get; set; }
        public virtual ICollection<Payment> Payments { get; set; }
        public DateTime CreatedOn { get; set; }
        public virtual  ICollection<DateTime> 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)。我是不是漏掉了一些非常明显的东西？

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Properties<DateTime>()
        .Configure(c => c.HasColumnType("datetime2"));

    modelBuilder.Entity<Account>().HasOptional(x => x.Addresses).WithMany();
    modelBuilder.Entity<Account>().HasOptional(x => x.Payments).WithMany();
    modelBuilder.Entity<Payment>().HasOptional(x => x.Products).WithMany();
    modelBuilder.Entity<Payment>().HasOptional(x => x.AccountID);
    modelBuilder.Entity<Payment>().HasKey(x => x.PaymentID);

}

编辑 3检查了 Account.FetchAccountFromIdentity() 并且它确实打开了一个新的上下文。所以它现在已被删除，我现在在 AddProduct 方法中使用上下文(上面更新的代码)。

现在保存时出现以下错误!!!

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'.

我试过在 OnModelCreating 方法中强制 PK 关系，但它似乎没有帮助。

为清楚起见，这里是 Payment 类:

public class Payment
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int PaymentID { get; set; }
    public virtual Account AccountID { get; set; }
    public virtual ICollection<Product> 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<Product>();
        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<Overview> Overviews { get; set; }
    public virtual ICollection<Process> 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

如果您查看 Entity Framework 生成的表，您会发现只有三个。给定您的数据模型，应该有将 Account 和 Payment 对象相互映射的联结表(同样适用于 Payment 和 Product ，您可能需要对您拥有的其他集合执行相同的操作)。

关于无法将 Products 的 List 转换为单个的异常是因为您的数据模型表明 Products是一个集合，但数据库表实际上将其存储为 Payment 和 Product 之间的外键(即单个实体)关系。

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

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Properties<DateTime>().Configure(c => c.HasColumnType("datetime2"));

    modelBuilder.Entity<Account>().HasMany(x => x.Addresses)
        .WithMany().Map(t => t.ToTable("AccountAddresses"));
    modelBuilder.Entity<Account>().HasMany(x => x.Payments)
        .WithMany().Map(t => t.ToTable("AccountPayments"));
    modelBuilder.Entity<Payment>().HasMany(x => x.Products)
        .WithMany().Map(t => t.ToTable("PaymentProducts"));
    modelBuilder.Entity<Payment>().HasOptional(x => x.AccountID);
    modelBuilder.Entity<Payment>().HasKey(x => x.PaymentID);
}

更改来自如下代码:

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

收件人:

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

这样做会指示 Entity Framework 创建联结表，允许 Payment 保存 Products 的集合。