viper in react native app

3 min read 22-01-2025

Viper architecture is a clean, maintainable way to structure your iOS and Android apps. While not natively supported in React Native, we can adapt its principles to build robust and scalable React Native applications. This article will guide you through integrating Viper-like principles into your React Native projects.

What is Viper Architecture?

Viper (View, Interactor, Presenter, Entity, Router) is a clean architecture pattern commonly used in iOS and Android development. It emphasizes a clear separation of concerns, making code easier to test, maintain, and scale.

View: This is your React Native component, responsible for rendering UI elements and handling user interactions. It doesn't contain business logic.
Interactor: This handles the business logic and interacts with data sources (e.g., APIs, databases). It's where your core application logic resides.
Presenter: This acts as an intermediary between the View and the Interactor. It transforms data received from the Interactor into a format suitable for display in the View and handles user input from the View.
Entity: This represents your data model. Think of this as your plain old JavaScript objects (POJOs).
Router: This is responsible for navigation between different screens in your application.

Adapting Viper for React Native

While React Native's component-based structure differs from the traditional iOS/Android approach, we can apply the core Viper principles. We'll focus on achieving a similar separation of concerns.

1. Defining the Components

Let's consider a simple example: a screen to display a list of users fetched from an API.

View (UserListScreen.js): This React Native component will display the list of users. It will call functions in the Presenter to fetch data and handle user actions.

import React, { useState, useEffect } from 'react';
import { View, Text, FlatList } from 'react-native';
import UserPresenter from './UserPresenter';

const UserListScreen = () => {
  const [users, setUsers] = useState([]);
  const presenter = new UserPresenter();

  useEffect(() => {
    presenter.getUsers().then(setUsers);
  }, []);

  return (
    <View>
      <FlatList
        data={users}
        renderItem={({ item }) => <Text>{item.name}</Text>}
      />
    </View>
  );
};

export default UserListScreen;

Interactor (UserInteractor.js): This handles fetching data from the API.

import axios from 'axios';

class UserInteractor {
  async getUsers() {
    try {
      const response = await axios.get('https://jsonplaceholder.typicode.com/users');
      return response.data;
    } catch (error) {
      console.error('Error fetching users:', error);
      return []; // Return empty array on error
    }
  }
}

export default UserInteractor;

Presenter (UserPresenter.js): This acts as a bridge between the View and Interactor.

import UserInteractor from './UserInteractor';

class UserPresenter {
  constructor() {
    this.interactor = new UserInteractor();
  }

  async getUsers() {
    return this.interactor.getUsers();
  }
}

export default UserPresenter;

Entity (User.js): A simple data model representing a user.

class User {
  constructor(id, name, email) {
    this.id = id;
    this.name = name;
    this.email = email;
  }
}

export default User;

Router: In React Navigation, you'd handle routing using navigation.navigate().

2. Testing

The clear separation of concerns facilitated by this adaptation makes testing much easier. You can easily unit test your Interactor and Presenter independently of your View.

Benefits of Using Viper-like Principles

Improved code organization: Clear separation of concerns results in cleaner, more maintainable code.
Enhanced testability: Independent modules are easier to test.
Increased scalability: Easier to add new features and modify existing ones without affecting other parts of the application.
Better collaboration: Different developers can work on different parts of the application concurrently.

Conclusion

While React Native doesn't directly enforce Viper architecture, adopting its principles significantly improves the structure and maintainability of your applications. By separating concerns and focusing on independent, testable modules, you'll build more robust and scalable React Native apps. Remember, the key is to embrace the spirit of Viper—separation of concerns—rather than rigidly adhering to its specific structure. Adapt it to fit your project's needs.