> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> On Behalf Of Julian J. M.
> Sent: 16 June 2011 11:43
> To: sqlalchemy
> Subject: [sqlalchemy] Accessing several databases
>
> Hello,
>
> I'm intending to use sqalchemy with orm for loading and storing my
> application's project files. Each sqlite database would be a project
> file, that will have several tables.
>
> I'd like to work with projects like this:
>
> project1=AppProject("/tmp/pr1.sqlite");
> project2=AppProject("/tmp/pr2.sqlite");
>
> item1 = project1.getItem(5) # item1 should be and object of a mapped
> class.
> item1.value="test"
> anotheritem = project1.getNewItem()
> anotheritem.value="this is new"
> # this should flush and commit the underlying session for project1,
> #modifying item with id 5, and adding a new one
> project1.commitEverything()
>
> item2 = project2.getItem(8)
> item2.value = "another test"
> project2.commitEverything()
>
>
> The problem i'm facing is how to create the engine, metadata, mapper,
> session, and the orm classes for each AppProject instance.
>
> I'm not sure if this is supported or even a good idea.
>
> Thanks,
> Julian J. M.
>
I think this should be pretty easy with a separate SQLAlchemy Session
per project. You would define all your mappers and so on without any
reference to a specific database:
##############################################################
# your_db_module.py
import sqlalchemy as sa
import sqlalchemy.orm as saorm
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class ProjectItem(Base):
__tablename__ = 'project_item'
id = sa.Column(sa.Integer, autoincrement=True, primary_key=True)
# other columns etc.
Then your AppProject class would look something like this:
##############################################################
# appproject.py
import sqlalchemy as sa
import sqlalchemy.orm as saorm
from your_db_module import ProjectItem
class AppProject(object):
def __init__(self, filename):
self.engine = sa.create_engine('sqlite://' + filename)
self.session = saorm.Session(bind=self.engine)
def get_item(self, id):
return self.session.query(ProjectItem).get(id)
Hope that helps,
Simon
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