Control Flow & Logic

Control flow in programming refers to the order in which individual statements, instructions, or function calls are executed or evaluated. Proper control flow is crucial for determining how your app responds to user inputs and events. Here are some key elements:

• Conditional Flows: These include if, else if, and else flows that allow your app to make decisions based on certain conditions. For example, you might check if a user is logged in and then show different content based on their authentication status.

• Loops: Loops allow your app to repeat a sequence of logic multiple times. This is useful for tasks like iterating through a list of items or retrying a failed operation.

• Event Handling: In certain cases, you will execute functions that are triggered by specific events such as user interactions (e.g., taps, swipes) or system events (e.g., page load, on focus change). Understanding how to handle such events effectively ensures that your app reacts appropriately to user interactions or events.

Logic or Functions refer to the core operations and behaviors that determine how an app responds to user actions and interacts with data. This could include:

• Business Logic: This is the part of the app that manages the rules and processes of the real world. For example, in an e-commerce app, it handles tasks like processing orders, calculating prices, and managing inventory.

• User Interface Logic: This controls how the app looks and interacts with users. It includes tasks like validating forms, navigating between screens, and updating content based on user actions.

• Data Logic: This manages the app's data. It includes tasks like fetching, storing, updating, and deleting data from databases or via APIs.

Let's dive into few more key concepts:

Functions

A function is a block of code designed to perform a specific task. Functions can be reused throughout your application to perform common tasks efficiently.

Triggers or Running a Function

Functions can be executed in various ways: they can be called from properties within the app, such as performing a quick calculation or number formatting before setting the final value to a variable, or concatenating strings before setting the string to a text widget. Functions can also run in response to specific events, such as a button click or a page load.

Types of Functions

There are different types of functions you can use in your app. Some examples in FlutterFlow are:

• Built-in Utility Functions: Functions that perform general utility tasks, such as formatting data or performing calculations. In FlutterFlow, you can use Code Expression for simple data manipulation tasks or use the Combine Text built-in function to concatenate strings.

• Actions: Sequence of Logic performed in response to user interactions. For example:

  • Updating State Variables: Functions that modify the current state or data of the app, page, or component.

  • Widget-specific Functions: Functions applicable to various widgets that need specific actions, such as scrolling to an item in a ListView, clearing text fields, or calling third-party integration functions.

  • Custom Actions: More complex actions written in Flutter & Dart that can be added as a node to the action flow editor.

• Navigation: Functions that handle the movement between different pages or screens within your app, including opening bottom sheets or dialogs. In FlutterFlow, such functions can either run automatically after certain related operations, such as Login/Create Account, or they can be added as individual Actions if the developer enables it.

• Backend Queries: Functions that interact with your database or external services to retrieve or manipulate data.

• Custom Functions: Complex manipulation code written in Dart, used to set properties of a widget or an action.