簡單的一對一關係實體框架代碼優先

Question

我有兩個表，一個用於客戶，另一個用於信用卡，並且它們之間存在簡單的一對一關係（這不是真正的數據，它是隻是爲了學習目的）。

即使沒有錯誤和數據在數據庫中，我不能顯示任何客戶的信用卡信息。

Customer.cs（模型）：

public class Customer 
{ 
    [Key] 
    public int Id { set; get; } 
    public string Username { set; get; } 
    public string Password { set; get; } 
    public string FirstName { set; get; } 
    public string Surname { set; get; } 
    public string Email { get; set; } 
    public CreditCard CreditCard { get; set; } 
} 

Customer表：

CreditCard.cs（模型）：

public class CreditCard 
{ 
    [Key, ForeignKey("Customer")] 
    public int Id { get; set; } 
    public string NameOnCard { get; set; } 
    public string CardNumber { get; set; } 
    public DateTime ExpiryDate { get; set; } 
    public string CCV { get; set; } 
    public Customer Customer { get; set; } 
} 

CreditCards表：

要顯示的模式，我只是從數據庫傳遞客戶我的看法：

控制器：

public class AuthenticationController : Controller 
{ 
    private SchemaDBContext db = new SchemaDBContext(); 
    public ActionResult Login() 
    { 
     User user = new User(); 
     return View(user); 
    } 

    [HttpPost] 
    public ActionResult Login(User user) 
    { 
     Customer customer = new Customer(); 
     if (ModelState.IsValid) 
     { 
      customer = db.Customers.FirstOrDefault(u => u.Username.Equals(user.Username) && u.Password.Equals(user.Password)); 
      if (customer!=null) 
      { 
       FormsAuthentication.SetAuthCookie(user.Username, false); 
       return View("test", customer); 
      } 
      else 
      { 
       ModelState.AddModelError("", "Login data is incorrect!"); 
      } 
     } 
     return View(customer); 
    } 
} 

查看：

@using MVC_COMP1562.Models 
@model Customer 

@Html.DisplayFor(model => model.Username) 
@Html.DisplayFor(model => model.Password) 
@Html.DisplayFor(model => model.FirstName) 
@Html.DisplayFor(model => model.Surname) 
@Html.DisplayFor(model => model.Email) 
@Html.DisplayFor(model => model.CreditCard.NameOnCard) 
@Html.DisplayFor(model => model.CreditCard.CardNumber) 
@Html.DisplayFor(model => model.CreditCard.CCV) 

種子初始化測試數據

public class SchemaDBInitializer : DropCreateDatabaseAlways<SchemaDBContext> 
    { 
     protected override void Seed(SchemaDBContext context) 
     { 
      var customers = new List<Customer> 
      { 
       new Customer 
       { 
        CreditCard = null, 
        Email = "carsonalexander@gmail.com", 
        Id = 1, 
        Password = "carsonPass", 
        Username = "carsonUser", 
        FirstName = "Alexander", 
        Surname = "Carson" 
       }, 
       new Customer 
       { 
        CreditCard = null, 
        Email = "alonsomeredith@gmail.com", 
        Id = 2, 
        Password = "alonsoPass", 
        Username = "alonsoUser", 
        FirstName = "Meredith", 
        Surname = "Alonso" 
       } 
      }; 

      customers.ForEach(s => context.Customers.Add(s)); 
      context.SaveChanges(); 

      var creditcards = new List<CreditCard> 
      { 
       new CreditCard 
       { 
        CardNumber = "1234 3456 7890 1111", 
        CCV = "111", 
        Customer = customers[0], 
        ExpiryDate = new DateTime(2018, 04, 01), 
        Id = 1, 
        NameOnCard = "Alexander Carson" 
       }, 
       new CreditCard 
       { 
        CardNumber = "2222 0000 1234 6877", 
        CCV = "222", 
        Customer = customers[1], 
        ExpiryDate = new DateTime(2019, 05, 01), 
        Id = 2, 
        NameOnCard = "Meredith Alonso" 
       } 
      }; 

      creditcards.ForEach(s => context.CreditCards.Add(s)); 
      context.SaveChanges(); 

     } 
    } 

Answer 1

如果有任何人有同樣的問題，我有過掙扎。

感謝格特·阿諾德我已經想通了，因爲我沒有真正給予任何數據，這是我在實體框架以爲對象子對象是自動的。

答案是延遲加載。

例如

每當我們在我們的模型類使用另一個模型作爲關係聲明它虛擬的，現在當你從數據庫中獲取他們的一切，否則將必須手動加載這些對象中的數據。

public class CreditCard 
{ 
    [Key, ForeignKey("Customer")] 
    public int Id { get; set; } 
    public string NameOnCard { get; set; } 
    public string CardNumber { get; set; } 
    public DateTime ExpiryDate { get; set; } 
    public string CCV { get; set; } 
    public virtual Customer Customer { get; set; } //<--- Here virtual 
}