The most efficient and correct approach is to create a single, custom client action that groups the two necessary steps: Reset Widgets for the form and assigning a value to a local variable that controls the visibility/text of the confirmation message. This keeps the logic encapsulated, performant (executes on the client), and is called from the appropriate event (On After Submit of the Ajax Submit).

The best practice is to use the built-in ‘Class’ property of the UI element (the row container) and set it with a conditional expression. This is declarative, clean, and performs well. The expression can directly reference the {List.Current.Status} and return the appropriate CSS class string. This avoids unnecessary widget nesting and complex logic.

The core issue is the ‘N+1 query problem’ or its server-action equivalent. Calling a server action for *each* item in a list results in a separate network request and server computation per item, which is disastrous for performance. The correct solution is to refactor the logic so the complex calculation is performed within the initial aggregate query on the server, returning the computed value as a ready-to-use attribute in the list records.

The most robust and maintainable method is to use OutSystems’ built-in application security. By defining a ‘Manager’ Role in the Service Center and assigning it to users, you can simply select that Role in the ‘Role’ property of the Block widget. The platform automatically handles visibility trimming (security) based on the logged-in user’s roles. This is centralized and secure.

The ‘Prevent Navigation with Feedback’ UI pattern is the standard, user-friendly solution for this scenario. It detects when input data has changed (dirty state) and, upon a navigation attempt (like clicking a menu item), triggers a client-side dialog asking the user to confirm or cancel the navigation, preventing accidental data loss.

The standard and efficient pattern for dependent dropdowns is to use an Aggregate (for Cities) with a filter parameter bound to the selected CountryId. Then, use an Ajax Refresh action (triggered by the On Change event of the Country dropdown) to refresh the City Aggregate and, by extension, the dropdown that uses it as its source. This keeps the logic simple and declarative.

A Session Entity is ideal for this use case. Its data is stored in the session cache, making it very fast to read (no database hit) and automatically scoped to the user’s session. It’s perfect for user-specific, non-persistent, or frequently accessed data like preferences, shopping carts, or temporary selections.

Server actions cannot directly trigger client-side navigation. The correct pattern is: 1) The Ajax Submit calls the server action. 2) Upon successful completion (On After Submit event), a client action executes. 3) This client action uses ‘Go to Screen’ to navigate to the confirmation screen. This cleanly separates server logic from client-side UI flow.

The standard feedback pattern involves a boolean variable (often named IsLoading). This variable is set to True before the Ajax Submit/Run Server Action call and set to False in the On After/On Exception events. The button’s ‘Enabled’ property (or an If around it) is bound to `not IsLoading`. A loading spinner’s ‘Visible’ property is bound to `IsLoading`. This provides clear, custom feedback and prevents duplicate submissions.

The most efficient and correct approach is to create a single, custom client action that groups the two necessary steps: Reset Widgets for the form and assigning a value to a local variable that controls the visibility/text of the confirmation message. This keeps the logic encapsulated, performant (executes on the client), and is called from the appropriate event (On After Submit of the Ajax Submit).0