Merge pull request canonical#175 from canonical/rollback-on-session-e…

…rror

Rollback db actions when connection invalidated

tests/__init__.py

@@ -1,14 +1,14 @@
 # Standard library
-from contextlib import redirect_stderr
 import io
 import os
 import unittest
 import warnings
+from contextlib import redirect_stderr
 
-# Packages
-from sqlalchemy_utils import database_exists, create_database
 import flask_migrate
 
+# Packages
+from sqlalchemy_utils import create_database, database_exists
 
 # Local
 from tests.fixtures.models import make_models
@@ -27,14 +27,14 @@
 functionality, but I don't know of a good way to do that right now.
 """
 
-from webapp import auth
 from tests.helpers import transparent_decorator
+from webapp import auth
 
 auth.authorization_required = transparent_decorator
 os.environ["DATABASE_URL"] = os.environ["TEST_DATABASE_URL"]
 
-from webapp.app import app, db  # noqa: E402
-
+from webapp.app import app  # noqa: E402
+from webapp.database import db  # noqa: E402
 
 # Create database if it doesn't exist
 with app.app_context():

webapp/app.py

@@ -4,16 +4,15 @@
 from apispec.ext.marshmallow import MarshmallowPlugin
 from canonicalwebteam.flask_base.app import FlaskBase
 from flask import jsonify, make_response
-from flask_migrate import Migrate
 
 from webapp.api_spec import WebappFlaskApiSpec
 from webapp.commands import register_commands
-from webapp.database import db
+from webapp.database import init_db
 from webapp.views import (
+    bulk_upsert_cve,
     create_notice,
     create_release,
     delete_cve,
-    bulk_upsert_cve,
     delete_notice,
     delete_release,
     get_cve,
@@ -27,7 +26,6 @@
     update_release,
 )
 
-
 app = FlaskBase(
     __name__,
     "ubuntu-com-security-api",
@@ -48,8 +46,7 @@
     }
 )
 
-db.init_app(app)
-migrate = Migrate(app, db)
+init_db(app)
 
 register_commands(app)
 

webapp/database.py

@@ -27,7 +27,19 @@
 To add the application context
 """
 
+from flask_migrate import Migrate
 from flask_sqlalchemy import SQLAlchemy  # noqa: E402
-
+from sqlalchemy import exc
 
 db = SQLAlchemy()
+
+
+def init_db(app):
+    db.init_app(app)
+    Migrate(app, db)
+
+    @app.errorhandler(exc.PendingRollbackError)
+    def handle_db_exceptions(error):
+        # log the error:
+        app.logger.error(error)
+        db.session.rollback()

webapp/views.py

@@ -16,8 +16,8 @@
 from sqlalchemy.exc import DataError, IntegrityError
 from sqlalchemy.orm import Query, load_only, selectinload
 
-from webapp.app import db
 from webapp.auth import authorization_required
+from webapp.database import db
 from webapp.models import (
     CVE,
     STATUS_STATUSES,