Mercurial > kallithea
comparison docs/contributing.rst @ 6639:2db16cda05ba
docs: clarify that Session usually should be called - methods should not be used directly
Documentation based on clarification by Søren Løvborg:
Session is the factory/singleton manager, which tracks the current session (per
thread). To end the current session entirely and destroy the Session object, we
call remove on the manager (Session.remove()). (A new session will be created
on-demand.)
Session() returns the current session for the active thread (or creates a new
session, if there's none). commit is a method of the SQLAlchemy Session class,
thus called as Session().commit() ... it's a method call on the current Session
object, not the session factory/manager.
SQLAlchemy may have some hackery to allow Session.commit() to be called, and
the call automatically redirect to the actual Session object... but that's a
hack and should be avoided.
TL;DR: for remove, call it on Session; for everything else, call it on
Session().
author | Mads Kiilerich <mads@kiilerich.com> |
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date | Sun, 14 May 2017 21:20:12 +0200 |
parents | 3af2dea756db |
children | 813e1f9d9c53 |
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180 | 180 |
181 Notes on the SQLAlchemy session | 181 Notes on the SQLAlchemy session |
182 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | 182 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
183 | 183 |
184 Each HTTP request runs inside an independent SQLAlchemy session (as well | 184 Each HTTP request runs inside an independent SQLAlchemy session (as well |
185 as in an independent database transaction). Database model objects | 185 as in an independent database transaction). ``Session`` is the session manager |
186 and factory. ``Session()`` will create a new session on-demand or return the | |
187 current session for the active thread. Many database operations are methods on | |
188 such session instances - only ``Session.remove()`` should be called directly on | |
189 the manager. | |
190 | |
191 Database model objects | |
186 (almost) always belong to a particular SQLAlchemy session, which means | 192 (almost) always belong to a particular SQLAlchemy session, which means |
187 that SQLAlchemy will ensure that they're kept in sync with the database | 193 that SQLAlchemy will ensure that they're kept in sync with the database |
188 (but also means that they cannot be shared across requests). | 194 (but also means that they cannot be shared across requests). |
189 | 195 |
190 Objects can be added to the session using ``Session().add``, but this is | 196 Objects can be added to the session using ``Session().add``, but this is |