some updates i made

.gitignore

@@ -141,4 +141,6 @@ cython_debug/
 # static files generated from Django application using `collectstatic`
 media
 static
-.vscode/
+.vscode/
+.idea/
+.envrc

app/database.py

@@ -1,13 +1,82 @@
+from pathlib import Path
+
+from flask import _app_ctx_stack, current_app, has_app_context
 from sqlalchemy import create_engine
+from sqlalchemy.engine.url import URL
 from sqlalchemy.ext.declarative import declarative_base
-from sqlalchemy.orm import sessionmaker
+from sqlalchemy.orm import scoped_session, sessionmaker
+from werkzeug.local import LocalProxy
+
+# Constants
+DB_EXTENSION_KEY = "sa_session"
+SQLALCHEMY_DATABASE_URL = URL("sqlite", database=str(Path.cwd().joinpath("test.db")))
+# SQLALCHEMY_DATABASE_URL = URL(
+#     "postgresql",
+#     username="user",
+#     password="password",
+#     host="postgresd",
+#     database="db",
+# )
 
-SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"
-# SQLALCHEMY_DATABASE_URL = "postgresql://user:password@postgresserver/db"
 
+# I see people adding this here and not sure if it's needed since `NullPool` is the default for SqLite.
+# Does need to be added when `StaticPool` is used.
 engine = create_engine(
     SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
 )
+
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
+# The mixin could have passed the mixin here as well.
+# Base = declarative_base(cls=DictMixIn)
 Base = declarative_base()
+
+
+def init_db(app):
+    """
+
+    Create ``scoped_session`` only if we are initializing within flask because sessions
+    will not close properly outside of the context.
+    We can add optional ``query_property`` to the ``Base``.
+
+    Parameters
+    ----------
+    app : flask.Flask
+
+    """
+
+    # Import models locally just to ensure they get added to the registry on app load
+    from app import models
+
+    db_session = scoped_session(SessionLocal, scopefunc=_app_ctx_stack.__ident_func__)
+    Base.query = db_session.query_property()
+    Base.metadata.create_all(bind=engine)
+
+    if DB_EXTENSION_KEY not in app.extensions:
+        app.extensions[DB_EXTENSION_KEY] = db_session
+        app.db = db_session
+
+    @app.teardown_appcontext
+    def remove_db_session(exception=None):
+        """Terminates all connections, transactions or stale, in session and checks them back into pool"""
+        db_session.remove()
+
+
+# A little too advanced maybe? skip?
+def _get_db():
+    """
+
+    Returns
+    -------
+    sqlalchemy.orm.Session
+        session obj stored in global Flask App.
+    """
+    if has_app_context():
+        assert (
+            DB_EXTENSION_KEY in current_app.extensions
+        ), "`db_session` might not have been registered with the current app"
+        return current_app.extensions[DB_EXTENSION_KEY]
+    raise RuntimeError("No application context found.")
+
+
+db = LocalProxy(_get_db)

app/main.py

@@ -1,28 +1,24 @@
-from flask import Flask, _app_ctx_stack, jsonify, url_for
+from flask import Flask, jsonify, url_for
 from flask_cors import CORS
-from sqlalchemy.orm import scoped_session
 
-from . import models
-from .database import SessionLocal, engine
-
-models.Base.metadata.create_all(bind=engine)
+from app import models
+from app.database import db, init_db
 
 app = Flask(__name__)
 CORS(app)
-app.session = scoped_session(SessionLocal, scopefunc=_app_ctx_stack.__ident_func__)
+init_db(app)
 
 
 @app.route("/")
 def main():
-    return f"See the data at {url_for('show_records')}"
+    href = url_for("show_records")
+    return f'See the data at <a href="{href}">{href}</a>'
 
 
 @app.route("/records/")
 def show_records():
-    records = app.session.query(models.Record).all()
-    return jsonify([record.to_dict() for record in records])
 
-
-@app.teardown_appcontext
-def remove_session(*args, **kwargs):
-    app.session.remove()
+    # records = app.db.query(models.Record).all()  # use db attribute
+    # records = models.Record.query.all()  # use query_property
+    records = db.query(models.Record).all()  # or use proxy
+    return jsonify([record.to_dict() for record in records])

app/models.py

@@ -1,7 +1,9 @@
+import datetime
+
 from sqlalchemy import Column, Integer, String
 from sqlalchemy.types import Date
+
 from .database import Base
-import datetime
 
 
 class DictMixIn:
@@ -16,7 +18,7 @@ def to_dict(self):
         }
 
 
-class Record(Base, DictMixIn):
+class Record(DictMixIn, Base):
     __tablename__ = "Records"
 
     id = Column(Integer, primary_key=True, index=True)