Question

I have an entity, let’s call it CommonEntity that has a primary key used as a foreign key in many other entities. As the application is developed these links will continue to grow.

I’d like a way to see if CommonEntity can be safely deleted (i.e. it’s not used by any other entities).

I realise I can do

if(!ce.EntityA.Any() && !ce.EntityB.Any() ... && !ce.EntityN.Any())
{
   //Delete
}

but I’m hoping for a way to just check all of the relationships automatically, as I don’t love the idea of having to come back and change this code manually every time we add a new relationship. Perhaps there is something in EF4+ that I’m not aware of?

I thought it might be possible to use a transaction scope to just try and delete the object and roll it back if it fails, but I wasn’t sure if there were any adverse side effects with this approach.

Is there a better approach?

EDIT: Looks like VS2012 has used EF5 even though the project is .Net 4, so it has created the model with POCOs even though it was generated from a DB.

Answer 1

Just let it fail. If the entity has many relationships, that verification could be really heavy.

public bool TryDelete(int id)
{
    try
    {
        // Delete
        return true;
    }
    catch (SqlException ex)
    {
        if (ex.Number == 547) return false; // The {...} statement conflicted with the {...} constraint {...}
        throw; // other error
    }
}