1

I have a robust set of objects that relate to one another and I need to figure out that best way to handle saving them to the database and still account for things like data constraints.

Let's say I have the following classes:

class Foo
{
    public int Id { get; set; }
    public int BarId { get; set; }
    Bar _bar;
    public Bar Bar 
    {
        get { return _bar; }
        set
        {
            if(_bar != value)
            {
                 _bar = value;
                 BarId = value.Id;
            }
        }
     }
}

class Bar 
{
    public int Id { get; set; }
}

Then let's say I have the following code:

var f = new Foo() { Bar = new Bar() };
SaveFoo(f);

What should I do in SaveFoo to save the objects to the database in the proper order?

IMPORTANT NOTE: I am code generating all of this from my SQL data structure using MyGeneration, and I have access to all Constraints while I'm generating.

Ben Lesh
  • 107,825
  • 47
  • 247
  • 232

1 Answers1

1

You have to work inside out.

If you have a "Navigation property" in your class (in this case, Bar in Foo) it will be accompanied with a foreign id (BarID). So you have to save your nested objects first before saving the object itself.

The problem you risk here are cyclic properties (Author write book, book has Author), in which case you have to properly define which is the primary relationship and which should be ignored.

Then the next problem is cascading deletes.

Was this what you were asking?

Daryl Teo
  • 5,394
  • 1
  • 31
  • 37
  • Basically, I guess I was just a little stumped, and I was hoping someone else had conquered this exact same problem. – Ben Lesh Sep 21 '11 at 00:54
  • Having built my own horrible horrible ORM before, I know how you feel :D There's a reason why I use 3rdparty ORMs where possible now. And even they haven't solved it. Entity Framework prevents you from doing cyclic relationships because it leads to multiple cascade paths. I believe this only affects 1-1 relationships though. – Daryl Teo Sep 21 '11 at 01:16
  • Well, I think I'm on the right path now, actually. I have a very customized set of needs for this app that nothing 3rd party fit like a glove. And it's my own pet project (unpaid) so I have a little leeway to screw around. – Ben Lesh Sep 21 '11 at 01:30
  • This led me the right way. What I did was basically code generate recursive save methods that followed relationships in both directions, saving dependencies first, but also saving dependents if they were found. It passed a HashSet of references around to make sure I didn't save the same data twice, which prevents cyclical behavior. Thanks again for the tip! – Ben Lesh Sep 21 '11 at 03:53