[update] Remove foreign key constraints

app/__init__.py

@@ -8,6 +8,7 @@ from app.errors import register_error_handlers
 from flask_sqlalchemy import SQLAlchemy
 from flask_migrate import Migrate
 
+
 db = SQLAlchemy()
 migrate = Migrate()
 
@@ -36,7 +37,7 @@ def create_app():
     # Error Handlers
     register_error_handlers(app)
     
-
+    from . import models
     # Database and Migrations
     db.init_app(app)