How to use local variables in OutSystems screens to store temporary states and values?

Using Local Variables in OutSystems Screens to Store Temporary States and Values

Local variables in OutSystems are vital for managing temporary states and values within screens, thus keeping interactions smooth and efficient. This guide outlines the process of effectively using local variables in your OutSystems applications.

Prerequisites

• Access to the OutSystems platform with an active project.
• Basic understanding of OutSystems architecture, widgets, and screen logic.
• Familiarity with the Service Studio in OutSystems.

Understanding Local Variables

• Local variables are used to store data temporarily and are scoped to a screen or a block.
• They can hold different data types: text, integers, booleans, records, lists, and more.
• Ideal for transient data that doesn't need to be stored in the database.

Creating Local Variables

1. Launch OutSystems Service Studio and open your project.
2. Select the screen where you wish to add a local variable.
3. In the 'Interface' tab, expand the 'Variables' section located in the lower toolbar.
4. Click on 'Add Local Variable'.
5. Define the variable's properties:
   • Name: A concise and descriptive name for the variable.
   • Data Type: Choose from among types like Text, Integer, Boolean, etc.
   • Default Value: (Optional) Set an initial value.

Using Local Variables in Screen Logic

1. With the local variable defined, you can utilize it in screen logic expressions and actions:
2. Navigate to the 'Logic' tab for the screen.
3. Drag and drop actions such as 'Assign', 'If', etc., from the 'Tools' menu for logical operations.
4. Utilize the local variable in expressions:
   • In 'Assign' actions, you can set the variable's value.
   • Use it in 'If' conditions to dynamically control screen behavior.

Binding Local Variables to Screen Widgets

1. Select the widget (e.g., Input, Text, Button) that requires dynamic data.
2. In the properties pane, bind the widget to the local variable:
3. For input fields, bind the 'Variable' property to your local variable.
4. For displaying data, bind the 'Text' property to your local variable using an expression like `VariableName`.

Testing and Debugging

• Execute your screen via the '1-Click Publish' button to deploy and run.
• Navigate the screens in the browser to ensure the local variables work as intended.
• Utilize the 'Debugger' tool within Service Studio to monitor variable values and ensure logic correctness.

Use Cases for Local Variables

• Storing temporary form input data for manipulation and validation before submission.
• Managing UI states such as toggling visibility of elements.
• Tracking user navigation or selection within a multi-step process.

Best Practices

• Use descriptive names for local variables to ensure code readability.
• Limit the use of local variables to temporary data to avoid state conflicts.
• Regularly clean up unused variables to maintain codebase clarity.

By following these guidelines, you can effectively leverage local variables within OutSystems to manage temporary states and values, ultimately enhancing the functionality and responsiveness of your applications.