Update sqlalchemy example to work with Python 3.8, 3.9 and 3.10

[ifeLawal]

When trying to work with this example I received the error:

AttributeError: module 'datetime' has no attribute 'UTC'

Doing some research, it seems the new pattern is to pull UTC from timezone. Making the suggested edit as a PR

Fixes # .

Changes proposed in this pull request:

[chrisinmtown]

Thanks for using my example! What version of Python are you using to run it? I'm using Python 3.13 and when I clone your repo, checkout your branch and run the example, I see this error:

INFO:root:Creating pet 1..
Traceback (most recent call last):
  File "/Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py", line 59, in <module>
    put_pet(id_, pet)
    ~~~~~~~^^^^^^^^^^
  File "/Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py", line 33, in put_pet
    pet["created"] = datetime.datetime.now(timezone.UTC)
                                           ^^^^^^^^^^^^
AttributeError: type object 'datetime.timezone' has no attribute 'UTC'. Did you mean: 'utc'?

In recent Python versions the datetime package has a UTC constant as an alias for datetime.timezone.utc according to https://docs.python.org/3/library/datetime.html. It was added in 2022 in this PR: python/cpython#91928

Still you have definitely caught something that blocks running the example in old(er) versions of Python. I recommend updating your PR to have the following code that works for me and also, I think, sorts the imports in the order that isort wants them to appear:

% git diff app.py
diff --git a/examples/sqlalchemy/app.py b/examples/sqlalchemy/app.py
index 7d04bc6..a61d383 100644
--- a/examples/sqlalchemy/app.py
+++ b/examples/sqlalchemy/app.py
@@ -1,9 +1,9 @@
-import datetime
 import logging
+from datetime import datetime, timezone
 
-import connexion
 import orm
-from connexion import NoContent
+
+from connexion import FlaskApp, NoContent
 
 
 def get_pets(limit, animal_type=None):
@@ -29,7 +29,7 @@ def put_pet(pet_id, pet):
             p.update(**pet)
         else:
             logging.info("Creating pet %s..", pet_id)
-            pet["created"] = datetime.datetime.now(datetime.UTC)
+            pet["created"] = datetime.now(timezone.utc)
             db_session.add(orm.Pet(**pet))
         db_session.commit()
         return NoContent, (200 if p is not None else 201)
@@ -56,7 +56,7 @@ pets = {
 }
 for id_, pet in pets.items():
     put_pet(id_, pet)
-app = connexion.FlaskApp(__name__, specification_dir="spec")
+app = FlaskApp(__name__, specification_dir="spec")
 app.add_api("openapi.yaml")
 app.add_api("swagger.yaml")

[ifeLawal]

Good catch! Appreciate the python links.

I was on Python 3.9.7 for my run of the example, an old(er) Python version that is not current. I updated the commit to match your diff for the PR.

[chrisinmtown]

I finally learned how to supply the appropriate arguments to isort to check examples. Unfortunately it is still not happy with your branch, a blank line is missing:

% isort --thirdparty connexion --check-only --diff app.py
ERROR: /Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py Imports are incorrectly sorted and/or formatted.
--- /Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py:before	2025-01-05 07:25:57.485152
+++ /Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py:after	2025-01-05 07:27:50.626244
@@ -3,6 +3,7 @@
 
 import orm
 from connexion import FlaskApp, NoContent
+
 
 def get_pets(limit, animal_type=None):
     with db_session_factory() as db_session:

I created a Python 3.9 venv to run your code, but the example still fails with the same error as before. Does this work for you?

% python3.9 app.py
INFO:root:Creating pet 1..
Traceback (most recent call last):
  File "/Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py", line 56, in <module>
    put_pet(id_, pet)
  File "/Users/me/git/github/connexion-ifelawal/examples/sqlalchemy/app.py", line 30, in put_pet
    pet["created"] = datetime.now(timezone.UTC)
AttributeError: type object 'datetime.timezone' has no attribute 'UTC'

Here's a diff that makes everything work:

% git diff app.py
diff --git a/examples/sqlalchemy/app.py b/examples/sqlalchemy/app.py
index 6e2e37c..f1d4042 100644
--- a/examples/sqlalchemy/app.py
+++ b/examples/sqlalchemy/app.py
@@ -4,6 +4,7 @@ from datetime import datetime, timezone
 import orm
 from connexion import FlaskApp, NoContent
 
+
 def get_pets(limit, animal_type=None):
     with db_session_factory() as db_session:
         q = db_session.query(orm.Pet)
@@ -27,7 +28,7 @@ def put_pet(pet_id, pet):
             p.update(**pet)
         else:
             logging.info("Creating pet %s..", pet_id)
-            pet["created"] = datetime.now(timezone.UTC)
+            pet["created"] = datetime.now(timezone.utc)
             db_session.add(orm.Pet(**pet))
         db_session.commit()
         return NoContent, (200 if p is not None else 201)

[ifeLawal]

Appreciate the diffs! I did a test with the lowercase timezone.utc on my local and that worked. Updated the spacing and the utc casing

[chrisinmtown]

Cool. You might want to update the first line of the commit message to be a bit more descriptive, I recommend something like this:

Update sqlalchemy example to work with Python 3.8, 3.9 and 3.10

[chrisinmtown]

+1 from me - but I'm not a maintainer so it doesn't really count lol