MVP (Model-View-Presenter) Architecture Pattern

Introduction

The Model-View-Presenter (MVP) is a software architectural pattern that facilitates the separation of concerns in an application. It is widely used in desktop and mobile applications to enhance testability and maintainability.

Key Concepts

Definitions

Model: Represents the data and business logic of the application.
View: Displays the data (UI) and sends user commands to the Presenter.
Presenter: Acts as an intermediary between the Model and the View, handling the presentation logic.

Architecture Overview

The MVP architecture is structured as follows:


            graph TD;
                A[View] -->|User Interaction| B[Presenter];
                B -->|Fetch Data| C[Model];
                C -->|Return Data| B;
                B -->|Update View| A;

This flowchart illustrates how user interactions are processed through the Presenter, which communicates with both the Model and the View.

Implementation

Here's a simple example of implementing MVP in a JavaScript application:


                // Model
                class UserModel {
                    constructor() {
                        this.users = [];
                    }
                    addUser(user) {
                        this.users.push(user);
                    }
                    getUsers() {
                        return this.users;
                    }
                }

                // View
                class UserView {
                    constructor(presenter) {
                        this.presenter = presenter;
                        this.userListElement = document.getElementById("userList");
                    }
                    showUsers(users) {
                        this.userListElement.innerHTML = users.map(user => `${user}`).join("");
                    }
                }

                // Presenter
                class UserPresenter {
                    constructor(view, model) {
                        this.view = view;
                        this.model = model;
                    }
                    addUser(user) {
                        this.model.addUser(user);
                        this.view.showUsers(this.model.getUsers());
                    }
                }

                // Usage
                const model = new UserModel();
                const view = new UserView();
                const presenter = new UserPresenter(view, model);
                presenter.addUser("John Doe");

Best Practices

Keep the View passive and focused only on UI rendering.
Ensure the Presenter contains all the business logic.
Use interfaces to decouple the View and Presenter.
Keep the Model independent from the View and Presenter.

FAQ

What are the advantages of using MVP?

MVP provides better separation of concerns, making the application easier to test and maintain. It also enhances reusability of components.

When should I use MVP over MVC?

MVP is preferred when you need more control over the view and when unit testing is a priority, especially in UI-heavy applications.