EF: many to many cascades
I have two objects that must have many different relationships. I am providing test data.
public class A
{
public int AId {get;set;}
public virtual ICollection<B> Bs {get;set;}
}
public class B
{
public int BId {get;set;}
public virtual ICollection<A> As {get;set;}
}
public class AMap : EntityTypeConfiguration<A>
{
public AMap()
{
HasMany(e => e.Bs)
.WithMany(e => e.As)
.Map(x =>
{
x.ToTable("AandB");
x.MapLeftKey("AId");
x.MapRightKey("BId");
});
}
}
In this configuration, I need to install cascading delete. For example, when I delete any row in table A, I need all related rows in table AandB to be deleted. But I cannot find the syntax for many for many. Help me?
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2 answers
After searching, I found a solution. To remove an object from a many-to-many relationship, you need to load the appropriate navigation property In my case:
var AtoDelete= context.As.Include(a => a.Bs) .First(); //include is mandatory
context.As.Remove(AtoDelete);
context.SaveChanges();//deletes will be issued to AandB table also.
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As I know there is no way to directly enable cascading deletes in many associations in the fluent API. you must explicitly delete related objects.
var a = context.A.Include(a => a.Bs).First();
foreach(var b in a.Bs)
{
context.Entry(b).State = EntityState.Deleted;
}
context.Entry(a).State = EntityState.Deleted;
context.SaveChanges();
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