ASP.Net MVC 3 EF「在表中引入FOREIGN KEY約束可能導致循環或多個級聯路徑」

Question

我正在創建一個ASP.Net MVC 3應用程序，並且在嘗試更新我的數據庫時遇到外鍵約束問題使用遷移。我使用的代碼優先，而我得到的錯誤是：

引進國外KEY約束「FK_CategoryItemValues_CategoryProperties_CategoryPropertyId」表「CategoryItemValues」可能會導致循環或多個級聯路徑。指定ON DELETE NO ACTION或ON UPDATE NO ACTION，或修改其他FOREIGN KEY約束。 無法創建約束。查看以前的錯誤。

這裏是我的課：

public class Category 
{ 
    public int Id { get; set; } 
    [Display(Name = "Category Name")] 
    public string CategoryName { get; set; } 
    [Display(Name = "Display Name")] 
    public string DisplayName { get; set; } 
    [Display(Name = "Display Order")] 
    public int DisplayOrder { get; set; } 
    public bool IsTab { get; set; } 
    public bool Active { get; set; } 

    public virtual List<CategoryProperty> Properties { get; set; } 
} 

public class CategoryProperty 
{ 
    public int Id { get; set; } 
    public int CategoryId { get; set; } 
    [Display(Name="Property Name")] 
    public string PropertyName { get; set; } 
    [Display(Name = "Display Order")] 
    public int DisplayOrder { get; set; } 

    public virtual Category Category { get; set; } 
} 

public class CategoryItem 
{ 
    public int Id { get; set; } 
    public int CategoryId { get; set; } 

    public virtual Category Category { get; set; } 
    public virtual List<CategoryItemValue> Values { get; set; } 
} 

public class CategoryItemValue 
{ 
    public int Id { get; set; } 
    public int CategoryItemId { get; set; } 
    public int CategoryPropertyId { get; set; } 
    public string Value { get; set; } 

    public virtual CategoryItem Item { get; set; } 
    public virtual CategoryProperty Property { get; set; } 
} 

protected override void OnModelCreating(DbModelBuilder modelBuilder) 
{ 
    // I know that the solution needs to go here! 
} 

好像我需要在刪除CategoryItemValues禁用級聯，但我不知道該怎麼做。我知道我需要做的是這樣的：

modelBuilder.Entity < ...>（） .HasRequired（...） .WithMany（...） .HasForeignKey（...） .WillCascadeOnDelete （假）;

但我不能完全正確。

Answer 1

這應該工作...

public class Category 
{ 
    public int Id { get; set; } 
    public string CategoryName { get; set; } 
    public string DisplayName { get; set; } 
    public int DisplayOrder { get; set; } 
    public bool IsTab { get; set; } 
    public bool Active { get; set; } 
    public virtual List<CategoryProperty> Properties { get; set; } 
    public virtual List<CategoryItem> Items { get; set; } 
} 
public class CategoryProperty 
{ 
    public int Id { get; set; } 
    public int CategoryId { get; set; } 
    public string PropertyName { get; set; } 
    public int DisplayOrder { get; set; } 
    public virtual Category Category { get; set; } 
    public virtual List<CategoryItemValue> Values { get; set; } 
} 
public class CategoryItem 
{ 
    public int Id { get; set; } 
    public int CategoryId { get; set; } 
    public virtual Category Category { get; set; } 
    public virtual List<CategoryItemValue> Values { get; set; } 
} 
public class CategoryItemValue 
{ 
    public int Id { get; set; } 
    public int CategoryItemId { get; set; } 
    public int CategoryPropertyId { get; set; } 
    public string Value { get; set; } 
    public virtual CategoryItem Item { get; set; } 
    public virtual CategoryProperty Property { get; set; } 
} 

...和 ​​'要點' ......

modelBuilder.Entity<CategoryProperty>() 
    .HasKey(i => i.Id); 

modelBuilder.Entity<CategoryProperty>() 
    .HasRequired(i => i.Category) 
    .WithMany(u => u.Properties) 
    .HasForeignKey(i => i.CategoryId) 
    .WillCascadeOnDelete(false); 

modelBuilder.Entity<CategoryItem>() 
    .HasKey(i => i.Id); 

modelBuilder.Entity<CategoryItem>() 
    .HasRequired(i => i.Category) 
    .WithMany(u => u.Items) 
    .HasForeignKey(i => i.CategoryId) 
    .WillCascadeOnDelete(false); 

modelBuilder.Entity<CategoryItemValue>() 
    .HasKey(i => i.Id); 

modelBuilder.Entity<CategoryItemValue>() 
    .HasRequired(i => i.Item) 
    .WithMany(u => u.Values) 
    .HasForeignKey(i => i.CategoryItemId) 
    .WillCascadeOnDelete(false); 

modelBuilder.Entity<CategoryItemValue>() 
    .HasRequired(i => i.Property) 
    .WithMany(u => u.Values) 
    .HasForeignKey(i => i.CategoryPropertyId) 
    .WillCascadeOnDelete(false);