Q:

From within a Doctrine record class, querying for the same record from the DB overwrites the properties within that class

In one of my Doctrine record classes, I have a preSave method that performs a check. In this check, a query is done on the same table that my record belongs to. This query will fetch one record from the table, and I use the hydrated result to compare to the current record represented by the class. 
In some cases, the fetched hydrated result will be the same record as the one I'm working with in the preSave check. However, when this happens, any changes that I've made to the first record are reverted once the query is completed.
Why does this happen? Is there a workaround?

A:

Doctrine might be maintaining a single reference to the record object instance, and not creating a whole new instance in your preSave() method.  So when the object is hydrated, any other variables of the same type in your code are 'refreshed'.  
To verify this, inspect the object ID's of variables in your code using spl_object_hash() function.  
Without seeing your code, workaround suggestions can vary, but one possible workaround is to hydrate an array in preSave():  
$query = Doctrine_Query::create()
->select('foo')
->from('Bar b')
->where('b.id = ?', $id);

$results = $query->execute(array(), Doctrine::HYDRATE_ARRAY);

You will lose the ability to use the result as an object, but you will be able to use the contents of the array for comparisons.

