如何作为参数传递DbSet <DerivedClass> 如果方法声明中有参数-DbSet <BaseClass>

Question

I have several derived classes (let call on of them DerivedClass ) from BaseClass .

I need to pass as a parametr DbSet <DerivedClass> to change entity DbSet:

in Library:

protected void ChangeEntity (DbSet <BaseClass> list) {

}

in Code:

DbSet <DerivedClass> list;
ChangeEntity (list); // Compillation error

How to pass derived class collection as a parameter?

Answer 1

If you only need to alter entity objects then make your ChangeEntity method accept IQueryable type instead:

protected void ChangeEntity (IQueryable<BaseClass> list) {}

Then you can call it in code:

DbSet <DerivedClass> list;
ChangeEntity (list);