Entity Framework Data Annotations equivalent of .W

问题:

I'm currently using EF Code First 4.3 with migrations enabled, but automatic migrations disabled.

My question is simple, is there a data annotations equivalent of the model configuration .WillCascadeOnDelete(false)

I would like to decorate my class so that the foreign key relationships do NOT trigger a cascading delete.

Code sample:

public class Container
{
    public int ContainerID { get; set; }
    public string Name { get; set; }

    public virtual ICollection<Output> Outputs { get; set; }
}

public class Output
{
    public int ContainerID { get; set; }
    public virtual Container Container { get; set; }

    public int OutputTypeID { get; set; }
    public virtual OutputType OutputType { get; set; }

    public int Quantity { get; set; }
}  

public class OutputType 
{
    public int OutputTypeID { get; set; }
    public string Name { get; set; }
}

I Would like to do something like this:

public class Output
{
    [CascadeOnDelete(false)]   
    public int ContainerID { get; set; }
    public virtual Container Container { get; set; }

    [CascadeOnDelete(false)]    
    public int OutputTypeID { get; set; }
    public virtual OutputType OutputType { get; set; }

    public int Quantity { get; set; }
}  

This way i would be able to scaffold the migration correctly. which scaffolds the foreign key relationships to be cascade deleted at the moment.

Any ideas, other than using Model Configuration?

回答1:

No there is no such equivalent. You must use fluent API to remove cascade delete selectively or you must remove OneToManyCascadeDelete convention to remove it globally.

回答2:

Create a mapping class (the fluent syntax) and use the code below:

// add relationships "Post" and "User" to a "Comment" entity
this.HasRequired(t => t.Post)
    .WithMany(t => t.Comments)
    .HasForeignKey(d => d.PostID)
    .WillCascadeOnDelete(false); // <---

this.HasOptional(t => t.User)
    .WithMany(t => t.Comments)
    .HasForeignKey(d => d.UserID)
    .WillCascadeOnDelete(false); // <---

Here's a nice post on how to set up fluent mappings if you need more info.

回答3:

Just make the FK property nullable can prevent cascade delete from happening:

public int? OutputTypeID { get; set; }