Structure your React Native app for Scale: - Part 1 -patterns and principles to master

Introduction:

In the dynamic landscape of software development, the architecture of your application stands as the backbone of its success. How you organize and structure your app can profoundly impact its maintainability, scalability, and overall development experience. In this article, we embark on a journey to unravel the principles that lay the groundwork for a well-structured and robust application.

When it comes to the structure and architecture of the React or React Native app, there are different design patterns, principles, and approaches to do that. Building a React Native app is like assembling a well-designed playground—each part has a purpose, creating a delightful experience for users.

Think of your React Native app's structure as crafting a cozy home. When everything is neatly organized, it's easy to add new features, fix issues, and keep everything running smoothly.

We'll chat about simple ideas like breaking down your app into smaller, manageable pieces, keeping important details secure, and using clever tricks to make your code understandable even if you're not a coding expert.

If you've ever ventured into the vast internet, you'll find an endless array of methods and approaches to structuring your app. Some are old as dirt, some are just plain wrong, and most will give you a structure without explaining why it works. As engineers, we demand more than just a blueprint; we want to understand the underlying principles that make these structures tick.

In the first part, we'll dive into the theoretical underpinnings of app structure, exploring the patterns, principles, and approaches that will empower you to build scalable, maintainable applications. We'll uncover the tips and tricks that keep your app running smoothly even when faced with massive growth. Along the way, we'll uncover the secrets that separate mere code monkeys from true engineering masters.

I will start talking about fundamental principles in software development: Modularization, abstraction, and encapsulation. their benefits and their importance. Each one of them can be achieved by using a set of React patterns which will be described later.

I will explain which tools and packages to use three of the principles to structure your app.

Still, in the aspect of React/ React native application, it is a little bit vague, so I will talk about Patterns that can be used to achieve that principle, and tools and principles to achieve that. After, I will talk about Patterns used in structuring our app, and I will end up talking about other considerations.

1- Modulization

Modulization involves breaking down a large application into smaller, self-contained modules. These modules can be organized into a hierarchical structure that mirrors the application's functionality or business logic. Each module focuses on a specific functionality or feature and can be developed, tested, and maintained independently.

a- Benefits of Modularization in React Native:

1. Improved Code Efficiency: Modularization promotes code reuse by enabling components to be used across multiple screens and sections of the application.
2. Enhanced Scalability: As your React Native app grows in complexity, modularization provides a scalable structure that accommodates new features or functionalities without disrupting existing code. This makes it easier to extend and maintain the application over time.
3. Separation of concerns: it allows developers to focus on specific features or functionalities. This separation improves code readability, and maintainability, and facilitates debugging and troubleshooting.
4. Collaborative Workflows: Modularization facilitates teamwork by enabling developers to work on different modules simultaneously. Each developer can be assigned specific modules, reducing conflicts and promoting efficient development workflows

b- Pattern to achieve Modularization in React Native:

1. Single Responsibility Principle: Each module or component should have a single responsibility or purpose. It is part of Solid Principles .
2. Component-Based Architecture: will be detailed later
3. Directory Structure: Organize your React Native project by creating directories for different types of modules, such as screens, components, utility functions, navigation routers, and assets. This directory structure allows for easy navigation and keeps related files together.
4. Clear Interfaces: Define clear interfaces and APIs for your modules to communicate with each other. This promotes loose coupling and encapsulation, allowing modules to interact without being tightly coupled to each other's internals.
5. Unit Testing: This will be explained later.
6. Documentation: Document each module's purpose, functionality, and usage. This documentation acts as a reference for other developers and aids in onboarding new team members.

2- Abstraction

Abstraction is a programming concept that involves simplifying complex systems by focusing on essential features while hiding unnecessary details. It allows developers to work with high-level representations of code or components without needing to understand every intricacy of their implementation.

This approach enhances code readability, reduces cognitive load, and promotes flexibility in handling changes.

a- Benefits of Abstraction in React Native:

1. Simplicity: Abstraction simplifies the code by hiding complex implementation details, making it easier to understand and use.
2. Reusability: Abstracted components can be easily reused across different parts of the app, reducing code duplication and promoting consistency.
3. Maintainability: Abstraction makes it easier to maintain and modify code, as changes can be made in one place without affecting other parts of the app.
4. Readability: Abstracted components provide a clean and concise interface, enhancing code readability and comprehension.

b- Pattern to achieve Abstraction in React Native:

1. Create Abstract Classes and Interfaces: Define abstract classes or interfaces to represent the shared functionality of related components. This promotes code reusability and maintainability.
2. Extract Reusable Functionality: Extract reusable functionality into separate modules or components. This allows you to easily share and modify common code across different parts of the app.
3. Utilize Higher-Order Components (HOCs): Employ HOCs to abstract common behavior and apply it to multiple components. This promotes code reuse and decouples logic from presentation. You can achieve that by creating also custom hooks that can abstract some of the work.
4. Document Abstracted Modules: Document the purpose, usage, and implementation of abstracted components or modules.
5. API Abstraction: Abstract API calls into separate modules or utility functions to encapsulate data-fetching details, by having an API folder to put API calls

3- Encapsulation

a- Definition and benefits:

Encapsulation is a software design principle that restricts direct access to the internal data and methods of a module or object, forcing users to interact with it through defined interfaces. This promotes code modularity, maintainability, and security.

b- Pattern to achieve Encapsulation in React Native:

Prop Drilling: Avoid prop drilling, where data is passed down through multiple levels of components. Use higher-order components, context, or state management libraries to decouple data flow and promote encapsulation.

Prop Types: Define prop types for your components to specify the expected data structure and prevent invalid data from being passed down. This promotes encapsulation and data validation.

Data Hiding: Avoid direct access to internal component data. Instead, use props or context to pass data between components, promoting encapsulation and data integrity. This ensures that only authorized code can modify the component state, preventing accidental or unintended changes

Component-Based Architecture: will be defined later

Component Libraries: will be defined later

4- Patterns To Master

Container-Component Pattern

The Container-Component pattern is a design pattern that separates the concerns of logic and presentation within a React Native component. It divides the responsibilities into two distinct types of components: Containers and Components.

• Containers: Containers are responsible for managing the application state, fetching data from APIs, handling events, and coordinating the logic behind the scenes. They encapsulate the business logic of the application.
• Components: Components focus solely on rendering the user interface (UI) and receiving props from the Container. They are primarily concerned with visual representation and user interaction.

Component-Based Pattern

The Component-Based Pattern is an architectural approach in software development, particularly prevalent in front-end frameworks like React. In this pattern, the application is structured as a composition of reusable, self-contained building blocks called components

Follow the principles of component-based architecture, where each module represents a self-contained unit with its logic and rendering. This ensures that components are reusable and independent of each other. by breaking down complex UI elements into smaller, reusable components.

Page Component

A Page Component is a reusable component in React that represents a single screen. It typically contains the screen's content, navigation, and any other necessary functionality.

Page Components are often organized into a hierarchy, with parent components managing the layout and flow of child components.

It is mainly about dividing your screen into smaller components, by taking into account the Single repository principle into mind, where each small component does one job

Feature Component

a feature component is a reusable component that encapsulates a specific feature or functionality of the application. It is designed to be independent and self-contained, allowing it to be easily integrated into different parts of the application without requiring extensive modifications.

An example will be having defined features such as the Authentification feature or the Error handling boundary.

Provider Pattern

The Provider Pattern is a design pattern in React that provides a mechanism for sharing data and functionality across multiple components in an application. It promotes code reuse, modularity, and maintainability by centralizing the management of global state and logic.

Example of using Redux for State management or React Context to pass the data. It solves the issue of Props Drilling.

State Management

Consider adopting a state management library like Redux or MobX to handle application-wide state. These libraries provide a structured way to manage and share data across components. Define clear actions and reducers to maintain a predictable state flow in your app.

In React Native, components have their own local state, which works well for simple applications. However, as the complexity of your app grows, managing the state becomes more challenging. Multiple components may need access to the same data, and keeping the state synchronized becomes crucial. This is where state management solutions come into play

Folder Structure

Creating a well-organized folder structure is crucial for maintaining a clean, scalable, and easily understandable codebase in a software project. While specific details may vary based on the project's size, type, and technology stack, here's a general guide for organizing your project folders

To achieve that: Group by Feature or Functionality: Organize files based on the features or functionalities they relate to. such as:

• src/screens: Contains individual application screens.
• src/components: Stores reusable UI components.
• src/utils: Holds utility functions or helper modules.
• src/assets: Houses images, fonts, and other static resources.
• src/navigation: Includes navigation-related files.

To achieve that, consider this:

1. Consistent Naming: Adopt a consistent naming convention for files and folders, using clear, descriptive names that convey their purpose.
2. Avoid Over-Nesting: Organize files hierarchically but avoid excessive nesting to prevent unnecessary complexity. Aim for a balance between organization and flat structure for easy navigation.
3. Use Index Files: Employ index files in directories as entry points to enhance code readability. Index files can export multiple files or provide an overview of folder contents.
4. Separate Configurations: Keep configuration files (e.g., package.json, .babelrc) at the project's root level for easy access and to maintain a clean folder structure.
5. Common Assets: Create a dedicated directory for common assets or resources shared across the application, promoting reusability and avoiding duplication.
6. Modularization: Embrace modularization by creating specific directories for modules or features, facilitating maintenance, testing, and code reuse.
7. Version Control: Implement a version control system (e.g., Git) to track code changes. Ensure the folder structure aligns with version control for consistency and collaborative development.

Testing

• Jest ?—?unit testing: Write unit tests for your modules to ensure they function as expected. Unit tests help catch bugs early, ensure code quality, and provide confidence when making changes or refactoring
• React Native Testing Library ?—?integration testing
• Detox ?—?e2e testing

Check my guide here about Unit and Integration Testing

and for E2E testing: Check This?

CI/CD

Today, moving fast is not just an advantage, it’s crucial for the survival of businesses. CI/CD allows you to ship your apps with confidence and peace of mind. If done right, CI/CD can significantly increase the pace of development & and distribution.

As discussed earlier, a top demotivating factor for many developers is sitting idle and waiting for processes to complete. It’s in the best interest of developers and businesses to automate tedious tasks so that developers can do innovative and productive work. Besides allowing developers to deliver apps and updates faster, CI/CD takes away the cost of managing & and maintaining different environments on development machines. As mentioned in the McKinsey survey :

• Fastlane

To get more understanding of how to use Fastlane for CI-CD, and integrate it with GitHub Actions, check this article

The Practical part of the implementation of Fastlane and Github actions for Continuous Integration and Continuous Delivery is this.

Maintaining code & and repo quality

As an application grows in size, the execution of tests becomes more costly. Thus, it is best to plan to save time and make sure there aren’t any fundamental issues (such as typos) in our code.

Static typing & and linting can help us avoid basic issues that could consume tons of our CI resources. Issues like spelling mistakes, linting, static type checking, and package audits can be performed on a developer’s machine when they commit any code to the repository. Git hooks can also assist in maintaining code quality across a large codebase with several contributors.

You can also use git hooks to check commit messages, make commit history more readable, and generate automated changelogs.?

One of the ways to have a better code is to use the Static Code Analysis approach, check this article for more details: https://medium.com/@malikchohra/guide-to-static-code-analysis-for-react-and-react-native-c745dfc250bd

There are other ways such as using Commitlint, Typescript properties, and Spell Checker

Tools/Libraries:

• Commitlint
• CSpell

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