Am 01.03.2011 um 21:52 schrieb demitri:
Hello, I have a question about integrating exisiting SQLAlchemy code with a TurboGears v2.1 project. I'm sure I'm doing it wrong as our program is relatively unstable. I have standalone code that describes a database connection, model classes, etc. We have a fair amount of code that imports it that is not TurboGears. I want to integrate these classes and database connection into a new TurboGears project. These are the steps I've taken; can someone point out where I'm going wrong or missing? * I am not using the built-in "authentication and authorization", but I think I said "yes" to it to have it include the database code. I don't know if that's right. * project/config/app_cfg.py The quickstart included a lot of code I'm not using. I commented out everything from "base_config.DBSession = apo_plates.model.DBSession" to the end of the file. * project/model/__init__.py I understand that this should be the single place where the database configuration lives. I also noted that TG really wants the scoped session object to be called "DBSession", which is fine. In this class I put: from mymodel.DatabaseConnection import db # defines connection, scoped session DBSession = db.Session Everything to "def init_model" is commented out since I define the engine and metadata in my class. But then I don't see what I'd put in init_model. Is this called automatically by the framework? I put a "pass" there. For the last line: from mymodel.ModelClasses import * # all db table/classes defined here * project/controllers/__init__.py My model classes don't seem to be in scope in the controllers, so I added this: from mymodel.ModelClasses import * * project/controllers/root.py I added the following: from project.model import DBSession #, metadata from project import model I don't know if the above is the correct recipe, but here is my remaining problem: where is the session object created? In the wiki example, I simply see: x = DBSession.query(... but as far as I can tell, DBSession is the *class* returned by scoped_session, not an instance. To make things work, I do:
A scoped session is a factory for the actual sesion - but you can use it directly, for that thread, there will be a local instance. So it's perfectly fine to call DBSession.<whatever>, it should work.
session = DBSession() on each page, but I don't think that's right. Finally, I also have to call session.flush(), but I also don't see this in example code. We have previously been putting the above line into project/controllers/ __init__.py, but I've been told this is Bad.
You do not need to call flush, unless you want to execute gathere SQL to e.g. create IDs. The final commit will automatically flush.
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