twolfson · February 12, 2025 16:48 · Mar 12, 2020 · Feb 4, 2015 · Feb 4, 2015
diff --git a/README.md b/README.md
@@ -1,3 +1,4 @@
+# Last update: Feb 3, 2015
 Flask-SQLAlchemy has some nice built-ins (e.g. accessing `query` directly on classes). To continue leveraging these nicities while still inside of a Celery worker, we need to make sure we setup/teardown in a similar fashion to Flask-SQLAlchemy does on Flask.
 
 ## Setup

diff --git a/README.md b/README.md
@@ -14,13 +14,17 @@ https://github.com/mitsuhiko/flask-sqlalchemy/blob/2.0/flask_sqlalchemy/__init__
 
 To create a similar experience, we can run teardown when a Celery task ends:
 
+> We put in a clause about `CELERY_ALWAYS_EAGER` to prevent conflicts with Flask's normal execution.
+
 ```python
 from celery.signals import task_postrun
 def handle_celery_postrun(retval=None, *args, **kwargs):
     """After each Celery task, teardown our db session"""
     if app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN']:
         if not isinstance(retval, Exception):
             db.session.commit()
-    db.session.remove()
+    # If we aren't in an eager request (i.e. Flask will perform teardown), then teardown
+    if not app.config['CELERY_ALWAYS_EAGER']:
+        db.session.remove()
 task_postrun.connect(handle_celery_postrun)
 ```
diff --git a/README.md b/README.md
@@ -0,0 +1,26 @@
+Flask-SQLAlchemy has some nice built-ins (e.g. accessing `query` directly on classes). To continue leveraging these nicities while still inside of a Celery worker, we need to make sure we setup/teardown in a similar fashion to Flask-SQLAlchemy does on Flask.
+
+## Setup
+Flask-SQLAlchemy uses `create_scoped_session` at startup which avoids any setup on a per-request basis.
+
+https://github.com/mitsuhiko/flask-sqlalchemy/blob/2.0/flask_sqlalchemy/__init__.py#L668
+
+This means Celery can piggyback off of this initialization.
+
+## Teardown
+Flask-SQLAlchemy tears down when we leave the request/application context.
+
+https://github.com/mitsuhiko/flask-sqlalchemy/blob/2.0/flask_sqlalchemy/__init__.py#L747-L753
+
+To create a similar experience, we can run teardown when a Celery task ends:
+
+```python
+from celery.signals import task_postrun
+def handle_celery_postrun(retval=None, *args, **kwargs):
+    """After each Celery task, teardown our db session"""
+    if app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN']:
+        if not isinstance(retval, Exception):
+            db.session.commit()
+    db.session.remove()
+task_postrun.connect(handle_celery_postrun)
+```
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