Fix: Add database engine None checks to prevent 500 errors

- Added engine None checks to get_hourly_traffic and get_vehicle_density_by_location
- Added safe_db_query helper function for future use
- Prevents AttributeError when database engine is None

database.py

@@ -93,6 +93,24 @@ except Exception as e:
     print(f"⚠️ Database connection warning: {e}")
     engine = None
 
+# =========================================================
+# HELPER: Safe Database Execution
+# =========================================================
+
+def safe_db_query(query_func):
+    """Decorator to safely execute database queries with None check"""
+    def wrapper(*args, **kwargs):
+        if engine is None:
+            print(f"⚠️ Database engine not available for {query_func.__name__}")
+            # Return appropriate empty result
+            return [] if 'get_' in query_func.__name__ else None
+        try:
+            return query_func(*args, **kwargs)
+        except Exception as e:
+            print(f"❌ Database query error in {query_func.__name__}: {e}")
+            return [] if 'get_' in query_func.__name__ else None
+    return wrapper
+
 # =========================================================
 # CONFIG
 # =========================================================
@@ -905,6 +923,10 @@ def health_check():
 def get_vehicles_by_state():
     """Get vehicle count by state with timeout protection"""
     
+    if engine is None:
+        print("⚠️ Database not available for get_vehicles_by_state")
+        return []
+    
     try:
         
         sql = """
@@ -929,6 +951,10 @@ def get_vehicles_by_state():
 def get_hourly_traffic():
     """Get traffic by hour with timeout protection"""
     
+    if engine is None:
+        print("⚠️ Database not available for get_hourly_traffic")
+        return []
+    
     try:
         
         sql = """
@@ -953,6 +979,10 @@ def get_hourly_traffic():
 def get_top_plates():
     """Get top detected plates with timeout protection"""
     
+    if engine is None:
+        print("⚠️ Database not available for get_top_plates")
+        return []
+    
     try:
         
         sql = """
@@ -1105,6 +1135,9 @@ def get_peak_traffic_hours():
 
 def get_vehicle_density_by_location():
     """Get traffic density (vehicle count) by location"""
+    if engine is None:
+        print("⚠️ Database not available for get_vehicle_density_by_location")
+        return []
     try:
         sql = """
         SELECT location, COUNT(*) as vehicle_count,