How to implement client-side filtering in OutSystems to refine the displayed list data?

Implementing Client-Side Filtering in OutSystems to Refine Displayed List Data

Client-side filtering is a powerful technique in OutSystems that allows users to filter displayed list data on the client side without the need for round trips to the server. This guide provides a comprehensive, step-by-step approach to implementing client-side filtering in OutSystems, enabling dynamic and responsive user experiences.

Prerequisites

• Basic understanding of OutSystems environment and terminology.
• Access to an OutSystems environment with development rights.
• An OutSystems project with a list or table widget ready for implementation.

Understanding Client-Side Filtering

• Client-side filtering involves applying filters to data that has already been fetched from the server, hence improving performance since it eliminates additional server requests.
• It is suitable for relatively small datasets that can be fully loaded onto the client's device.

Setting Up Your OutSystems Environment

• Log in to your OutSystems environment and open the specific application module where you want to apply client-side filtering.
• Ensure your Screen has a list or table widget that displays data you wish to filter.

Creating a Filter Input

• In the desired screen, add an input widget (Text Box) to serve as the user interface element for entering filter criteria.
• Label this input clearly so users understand its purpose, such as "Search" or "Filter by Name".
• Bind this input widget to a local variable (e.g., `FilterText`) that stores the user's filter input.

Binding the Filter Logic to the List

• Ensure your list widget is bound to a local or entity aggregate that holds the data you want to display.
• Set the aggregate to fetch all data on screen load, as it won't query after applying client-side filters.
• Using OutSystems expressions, filter the list items based on the user input contained within the `FilterText` variable.
• Example Expression:

      List.Filter(
        ToLowerCase(Entity.ListAttribute) contains ToLowerCase(FilterText)
      )
      

  Replace `Entity.ListAttribute` with the appropriate fields you wish to compare with the filter input.

Handling UI Updates

• Ensure the list control is wrapped in a container if it's not already, to allow it to be refreshed dynamically when filters are applied.
• Use OutSystems UI patterns such as button events tied to the input to trigger refreshing or real-time filtering as users type. This can often be handled through input properties like 'OnChange'.

Testing Client-Side Filtering

• Use the OutSystems preview mode to test filtering. Enter search criteria in the input and check if the list updates accordingly without server interactions.
• Test with different input scenarios, including no matches, partial matches, and multiple field matches, ensuring expected behaviors under all conditions.

Optimizing and Deploying Your Solution

• Review performance when dealing with larger datasets and consider server-side filtering if data sets become unmanageable on the client side.
• Deploy your app to a test environment to invite other users to provide feedback on the filtering feature's usability and responsiveness.
• Ensure there is clear user guidance on how to use the filtering feature, such as placeholders in the filter input.

By following these steps, you can successfully implement client-side filtering in OutSystems to dynamically refine displayed list data. This approach enhances user interactions by providing immediate feedback and a smooth user experience.