# Data Types In Digia, **Variables** are containers for data. Every variable has a specific **Type**, which determines what kind of data it can hold and what operations you can perform on it. We categorize types into two main groups: **Scalar Types** (Primitive values) and **Controller Types** (Objects that control UI). ## Scalar Types These are the fundamental building blocks of your data. > \[!TIP] **Data Manipulation**: Data is rarely static. You often need to capitalize a name, calculate a total price, or filter a list. Digia provides built-in **Operations** for each type to handle this. Check the "Operations" column below to see what's possible. | Type | Description | Examples & Use Cases | Operations | | ----------- | ---------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- | | **String** | Textual data. Can contain letters, numbers, symbols, and emojis. |

Ex: "Hello", "user\_123"
Uses: Usernames, Titles, URLs.

| [String Operations](https://docs.digia.tech/logic-and-interaction/adding-logic/string-operations) | | **Number** | Numeric values (integers or decimals). |

Ex: 42, 3.14, -10
Uses: Prices, Quantity, Ratings.

| [Math Operators](https://docs.digia.tech/logic-and-interaction/adding-logic/math-operators) | | **Boolean** | True/False values. Logic gates. |

Ex: true, false
Uses: Toggles, Visibility, Conditions.

| [Logical Operators](https://docs.digia.tech/logic-and-interaction/adding-logic/logical-operators) | | **JSON** | Structured key-value pairs. Standard for API responses. |

Ex: {"id": 1, "name": "Digia"}
Uses: API Data, Config.

| [JSON Operators](https://docs.digia.tech/logic-and-interaction/adding-logic/json-operators) | | **List** | Ordered collection of items. |

Ex: \["Apple", "Banana"]
Uses: Feeds, Galleries, Menus.

| [Iterable Operators](https://docs.digia.tech/logic-and-interaction/adding-logic/iterable-operators) | *** ## Controllers Controllers are special objects that bind to a Widget to control its behavior programmatically. > \[!NOTE] **Are Controllers Mandatory?** No. Most widgets work perfectly fine without a controller. You only need to create one if: > > * You need to **manipulate the widget from outside** (e.g., a "Reset" button that clears a TextField). > * You need the widget's **state to persist** (e.g., keeping the scroll position when navigating between tabs). Below is the list of available methods for each controller. ### ScrollController Manages the scroll position of a scrollable widget. **Attached to**: `ScrollView`, `ListView`, `GridView`. | Method | Arguments | Description | | ------------- | -------------------------------------------------------------------------------------------------------- | ------------------------------------------------- | | **jumpTo** | `offset` (Number) | Instantly jumps to the specified scroll position. | | **animateTo** |

offset (Number)
durationInMs (Number)
curve (String)

| Smoothly scrolls to the position over time. | ### PageController Controls which page is currently visible in a PageView or Carousel. **Attached to**: `PageView`, `Carousel`. | Method | Arguments | Description | | ----------------- | ------------------------------------------------------------------------------------------------------ | ---------------------------------------------- | | **nextPage** |

durationInMs (Number)
curve (String)

| Animates to the next page. | | **previousPage** |

durationInMs (Number)
curve (String)

| Animates to the previous page. | | **jumpToPage** | `page` (Number) | Instantly jumps to the specified page index. | | **animateToPage** |

page (Number)
durationInMs (Number)
curve (String)

| Smoothly animates to the specified page index. | ### TextEditingController Manages the text content and selection of a text input field. **Attached to**: `TextField`, `TextFormField`. | Method | Arguments | Description | | ------------ | --------------- | ----------------------------------- | | **setValue** | `text` (String) | Sets the text content of the field. | | **clear** | - | Clears the text field. | ### StreamController Manages a stream of data events. Useful for broadcasting updates to a StreamBuilder. **Attached to**: `StreamBuilder`. | Method | Arguments | Description | | --------- | ------------- | ---------------------------------------------------------- | | **add** | `value` (Any) | Pushes a new value to the stream, triggering a UI rebuild. | | **close** | - | Closes the stream. | ### TimerController Controls a countdown or stopwatch timer. **Attached to**: `Timer` widget. | Method | Arguments | Description | | ---------- | --------- | ----------------------------------------- | | **start** | - | Starts the timer. | | **pause** | - | Pauses the timer. | | **resume** | - | Resumes the timer from where it left off. | | **reset** | - | Resets the timer to its initial state. | ### AsyncController Manages the state of an asynchronous operation (Future). **Attached to**: `AsyncBuilder` (FutureBuilder). | Method | Arguments | Description | | -------------- | --------- | ----------------------------------------------- | | **invalidate** | - | Forces the Future to re-run (refresh the data). | ### StoryController Controls the playback and navigation of a Story widget. **Attached to**: `Story` widget. | Method | Arguments | Description | | ------------ | ---------------- | ------------------------------------- | | **play** | - | Plays the story. | | **pause** | - | Pauses the story. | | **next** | - | Skips to the next story item. | | **previous** | - | Goes back to the previous story item. | | **jumpTo** | `index` (Number) | Jumps to a specific story index. | | **mute** | - | Mutes the story audio. | | **unMute** | - | Unmutes the story audio. | ## How to use a Controller? 1. **Define it**: specific the controller type in your Page State or App State. 2. **Attach it**: Select the widget (e.g., ListView) and bind its `controller` property to your variable. 3. **Call it**: In an Action (like "On Tap"), choose **Control Object** and select your controller variable to trigger a method (like `animateTo`).