def empty_session():
engine = create_engine(TEST_DATABASE_URI_IN_MEMORY)
metadata.create_all(engine)
for table in reversed(metadata.sorted_tables):
engine.execute(table.delete())
map_model_to_tables()
session_factory = sessionmaker(bind=engine)
yield session_factory()
metadata.drop_all(engine)
clear_mappers()
def database_engine():
engine = create_engine(TEST_DATABASE_URI_FILE)
clear_mappers()
metadata.create_all(engine) # Conditionally create database tables.
for table in reversed(metadata.sorted_tables): # Remove any data from the tables.
engine.execute(table.delete())
map_model_to_tables()
database_repository.populate(engine, TEST_DATA_PATH_DATABASE)
yield engine
metadata.drop_all(engine)
clear_mappers()
def session_factory():
clear_mappers()
engine = create_engine(TEST_DATABASE_URI_IN_MEMORY)
metadata.create_all(engine)
for table in reversed(metadata.sorted_tables):
engine.execute(table.delete())
map_model_to_tables()
session_factory = sessionmaker(bind=engine)
database_repository.populate(engine, TEST_DATA_PATH_DATABASE)
yield session_factory
metadata.drop_all(engine)
clear_mappers()
def create_app(test_config=None):
"""Construct the core application."""
# Create the Flask app object.
app = Flask(__name__)
# Configure the app from configuration-file settings.
app.config.from_object('config.Config')
data_path = os.path.join('CompSciFlix', 'adapters', 'data')
if test_config is not None:
# Load test configuration, and override any configuration settings.
app.config.from_mapping(test_config)
data_path = app.config['TEST_DATA_PATH']
# Here the "magic" of our repository pattern happens. We can easily switch between in memory data and
# persistent database data storage for our application.
if app.config['REPOSITORY'] == 'memory':
# Create the MemoryRepository instance for a memory-based repository.
repo.repo_instance = memory_repository.MemoryRepository()
memory_repository.populate(data_path, repo.repo_instance)
elif app.config['REPOSITORY'] == 'database':
# Configure database.
database_uri = app.config['SQLALCHEMY_DATABASE_URI']
# We create a comparatively simple SQLite database, which is based on a single file (see .env for URI).
# For example the file database could be located locally and relative to the application in covid-19.db,
# leading to a URI of "sqlite:///covid-19.db".
# Note that create_engine does not establish any actual DB connection directly!
database_echo = app.config['SQLALCHEMY_ECHO']
database_engine = create_engine(database_uri, connect_args={"check_same_thread": False}, poolclass=NullPool,
echo=database_echo)
if app.config['TESTING'] == 'True' or len(database_engine.table_names()) == 0:
print("REPOPULATING DATABASE")
# For testing, or first-time use of the web application, reinitialise the database.
clear_mappers()
metadata.create_all(database_engine) # Conditionally create database tables.
for table in reversed(metadata.sorted_tables): # Remove any data from the tables.
database_engine.execute(table.delete())
# Generate mappings that map domain model classes to the database tables.
map_model_to_tables()
database_repository.populate(database_engine, data_path)
else:
# Solely generate mappings that map domain model classes to the database tables.
map_model_to_tables()
# Create the database session factory using sessionmaker (this has to be done once, in a global manner)
session_factory = sessionmaker(autocommit=False, autoflush=True, bind=database_engine)
# Create the SQLAlchemy DatabaseRepository instance for an sqlite3-based repository.
repo.repo_instance = database_repository.SqlAlchemyRepository(session_factory)
# Build the application - these steps require an application context.
with app.app_context():
# Register blueprints.
from .home import home
app.register_blueprint(home.home_blueprint)
from .news import news
app.register_blueprint(news.news_blueprint)
from .browse import browse
app.register_blueprint(browse.browse_blueprint)
from .authentication import authentication
app.register_blueprint(authentication.authentication_blueprint)
from .utilities import utilities
app.register_blueprint(utilities.utilities_blueprint)
# Register a callback the makes sure that database sessions are associated with http requests
# We reset the session inside the database repository before a new flask request is generated
@app.before_request
def before_flask_http_request_function():
if isinstance(repo.repo_instance, database_repository.SqlAlchemyRepository):
repo.repo_instance.reset_session()
# Register a tear-down method that will be called after each request has been processed.
@app.teardown_appcontext
def shutdown_session(exception=None):
if isinstance(repo.repo_instance, database_repository.SqlAlchemyRepository):
repo.repo_instance.close_session()
return app