Added development functionalities from dev branch

api/utils.py

@@ -2,17 +2,22 @@ from flask import abort
 from flask_jwt_extended import get_jwt_identity
 from models import User, db
 import os
+from sqlalchemy import text
+from sqlalchemy.exc import DatabaseError, InterfaceError
+import time
 from werkzeug.security import generate_password_hash
 
+db_ready = False
 
 def admin_required(user_id, message='Access denied.'):
+    "Check if common user try to make administrative action."
     user = db.session.get(User, user_id)
     if user is None or user.role != "Administrator":
         abort(403, message)
 
 
 def validate_access(owner_id, message='Access denied.'):
-    # Check if user try to access or edit resource that does not belong to them 
+    "Check if user try to access or edit resource that does not belong to them."
     logged_user_id = int(get_jwt_identity())
     logged_user_role = db.session.get(User, logged_user_id).role
     if logged_user_role != "Administrator" and logged_user_id != owner_id:
@@ -27,6 +32,20 @@ def get_user_or_404(user_id):
     return user
 
 
+def wait_for_db(max_retries):
+    "Try to connect with database <max_retries> times."
+    global db_ready
+    for _ in range(max_retries):
+        try:
+            with db.engine.connect() as connection:
+                connection.execute(text("SELECT 1"))
+            db_ready = True
+            return
+        except DatabaseError | InterfaceError:
+            time.sleep(3)
+    raise Exception("Failed to connect to database.")
+
+
 def init_db():
     """Create default admin account if database is empty"""
     with db.session.begin():