Variables

Variables in Digia allow you to store and manage data throughout your app. They come in two main categories: Basic Data Types for storing standard values, and Controller Types for controlling widget behavior and runtime interactions.

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📦 Basic Data Types

Basic data types store standard values like text, numbers, and structured data.

Type	Description	Documentation
String	A sequence of characters for text values	Learn more
Number	Integers and decimal numbers	Learn more
Boolean	true or false values	Learn more
JSON	Dynamic map-like structure with key-value pairs	Learn more
List	An ordered array of values	Learn more

StringNumberBooleanJSONList

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🧰 Controller Types

Controller types are special variables with methods that control widget behavior at runtime. Use the Control Object action to invoke their methods.

Type	Description	Supported Widgets	Documentation
Scroll Controller	Controls scrolling behavior	ListView, GridView, Smart Scroll View, Animation Builder	Learn more
Page Controller	Manages page navigation in PageView	PageView, Animation Builder	Learn more
Text Field Controller	Manages text input fields	Text Form Field	Learn more
Stream Controller	Pushes and listens to data streams	Stream Builder	Learn more
Async Controller	Manages async state and cache invalidation	Future Builder	Learn more
Timer Controller	Controls timer operations	Timer	Learn more

Scroll ControllerPage ControllerText Field ControllerStream ControllerAsync ControllerTimer Controller

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� Variable Scope

Variables can be defined in different scopes depending on where you need to use them:

Page State

Variables defined in Page State are:

• Mutable (can be changed)

• Scoped to the current page

• Reset when navigating away from the page

• Ideal for temporary UI state, form data, or page-specific logic

Page Properties

Variables defined in Page Properties are:

• Immutable (read-only)

• Passed as arguments when navigating to the page

• Used to pass data between pages

• Ideal for IDs, configuration, or data from previous pages

App State

Variables defined in App State are:

• Mutable (can be changed)

• Global across the entire app

• Persist across page navigation

• Ideal for user data, authentication state, or app-wide settings

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🎯 Best Practices

• Use appropriate types: Choose the simplest type that fits your data (String for text, Boolean for toggles, etc.)

• Name descriptively: Use clear, descriptive names (userName instead of u1)

• Initialize with defaults: Always set initial values to avoid null/undefined errors

• Scope appropriately: Use Page State for temporary data, App State for persistent data

• One controller per widget: Each controllable widget should have its own controller variable

• Clean up controllers: Close streams and clean up controllers when no longer needed

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Related Documentation

• Setting State - How to update variable values

• Control Object - Invoking controller methods

• Expressions and Operators - Using variables in logic

• API Calls - Storing API response data in variables