Castle Active Record NHibernate Same Session 2 versions of the same object

Question

I have a Car in DB where Model field is "Ferrari"

using (new TransactionScope())
{
    var car = Find(1);
    car.Model = "Ferrari Plus";

    // i need the old Car value to make a comparison
    var car2 = Find(1);

    // i need here the db Car record, instead i have the cached Nhibernate value
    if (car2.Model == 'Ferrari") 
        // do something
}

i modified the code in this way

using (new TransactionScope())
{
    var car = Find(1);
    car.Model = "Ferrari Plus";

    // i need the old Car value to make a comparison
    using (new TransactionScope())
    {
        var car2 = Find(1);
        // i got  the db value buuuuuuut
        // if i save because i need to save the modific Car i got an error
        if (car2.Model == 'Ferrari") 
            car.Save(); // ERROR: 2 objects with the same id exists
    }

}

how can i avoid this problem? How can i get 2 versions of the same object into the same NHibernate Session?

Answer 1

One of the base principles of nhibernate is to not have 2 objects that are the same in the same session. What you are asking cannot be done as far as I know.

Possible Solution 1

You could query car in one session close the session. Query car2 in another session and do your compare against the two objects. Update car2 with car's properties.

Possible Solution 2

Do the same as above except don't copy the values from car to car2. Instead you would open another session and do a session.Update(car);

Possible Solution 3

You could do is to create a copy of the original or create a dto. When you do your comparison compare the persistent instance (changed copy) to the copy/dto.