On Mar 31, 2008, at 12:02 PM, pyplexed wrote:

>
> The continuing adventures of a newbie SA user...
>
> Could anyone tell me if there is a simple way of setting up a query
> which takes an object as an argument and checks for the existence of
> an object in the database?

by primary key ?   assuming as below you don't have any prior  
knowledge of the object's properties or type,   
sess 
.query 
(obj.__class__).get(object_mapper(obj).primary_key_from_instance(obj))

> I know I can construct a query hard coding attributes to filter on,
> but I'm sure there is a better way to do this.

the above is a little ugly so you could make a function that does it,  
given any object (or even make it a classmethod on a base class).

> Ideally, the query would need to handle attributes containing multiple
> objects expressing many to many relationships.

Im not entirely sure what this means.  You'd like to query for an  
object based on its many-to-many association to another object ?  This  
would look like:

sess 
.query 
(DesiredClass 
).filter(DesiredClass.somerelation.contains(some_given_object)).all()


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