Forem: Houda-DE

Mastering the Builder Design Pattern: Simplifying Complex Object Creation

Houda-DE — Mon, 11 Nov 2024 11:55:26 +0000

Introduction

All of us, as developers, have encountered situations where we need to create an object. The problem with trying to design a generic class for this object is that it can take multiple forms. A simple example: the User class of a platform. For a regular user, we might only need an email and a username. However, for a platform administrator, additional attributes like a phone number might be required. We could also have a Premium user, where an extra field like a credit card number is needed, and so on.

So, how can we proceed in a generic way?

Faced with this problem, the developer community agreed on a popular creation pattern: the Builder Design Pattern. This pattern involves separating the construction of a complex object from its representation, allowing multiple object variants to be created using the same construction process.

This pattern is especially useful with objects that have many attributes, some of which may be optional for certain cases but not for others, or for objects that require a detailed initialization process. It allows for the flexible, step-by-step creation of objects without making the code overly complex or the constructor too overloaded.

Sections We Will Cover

What is the Builder Pattern?
When you should use it?
Real-World Examples of Builder Use
Why this pattern is so important?
Conclusion ## What is the Builder Pattern? The Builder Design Pattern is a creational design pattern that allows for the controlled and flexible construction of complex objects. Instead of having a constructor that takes a large number of parameters, the builder provides a smooth interface to create objects step by step. It is useful when the object has many attributes, specific construction steps, or multiple possible configurations.

When you should use it?

The Builder Design Pattern is particularly useful in the following cases:

If an object has many attributes, some of which are optional: Going back to the problem we posed at the beginning of this article, let’s consider the User class. Based on the logic we described, if we instantiate this User class, we could have different cases: for a regular user, normalUser = new User("houda", "houda@gmail.com", null, null), for an admin adminUser = new User("houda", "houda@gmail.com", "0657...", null), and for a premium user, premiumUser = new User("houda", "houda@gmail.com", null, "1234..."). This results in many null values in the instantiation.
Objects with a multi-step creation process: An example is a Order class. The first step is to place the order, which is then prepared, and finally delivered. Preparing an order may require multiple steps, and to ensure the correct order of construction, the builder design pattern is very useful.
Supporting multiple representations of the same object: For example, a Clothing class that has attributes for fabric, color, and brand. A clothing item can be a Pants, T-Shirt, or other types. Here, the builder pattern helps create different representations of the same base class.

Real-World Examples of Builder Use

for each case we have seen in the section before we will see the implementation of the builder

If an object has many attributes, some of which are optional:

class User {
    username: string;
    email: string;
    phoneNumber?: string;
    creditCard?: string;

    private constructor(builder: UserBuilder) {
        this.username = builder.username;
        this.email = builder.email;
        this.phoneNumber = builder.phoneNumber;
        this.creditCard = builder.creditCard;
    }

    public static get Builder() {
        return new UserBuilder();
    }
}

class UserBuilder {
    username!: string;
    email!: string;
    phoneNumber?: string;
    creditCard?: string;

    public setUsername(username: string): UserBuilder {
        this.username = username;
        return this;
    }

    public setEmail(email: string): UserBuilder {
        this.email = email;
        return this;
    }

    public setPhoneNumber(phoneNumber: string): UserBuilder {
        this.phoneNumber = phoneNumber;
        return this;
    }

    public setCreditCard(creditCard: string): UserBuilder {
        this.creditCard = creditCard;
        return this;
    }

    public build(): User {
        return new User(this);
    }
}

// Usage
const normalUser = User.Builder
    .setUsername("houda")
    .setEmail("houda@gmail.com")
    .build();

const adminUser = User.Builder
    .setUsername("houda")
    .setEmail("houda@gmail.com")
    .setPhoneNumber("0657....")
    .build();

const premiumUser = User.Builder
    .setUsername("houda")
    .setEmail("houda@gmail.com")
    .setCreditCard("1234....")
    .build();

Objects with a multi-step creation process:

class Order {
    private state: string;

    private constructor(builder: OrderBuilder) {
        this.state = builder.state;
    }

    public static get Builder() {
        return new OrderBuilder();
    }

    public getState(): string {
        return this.state;
    }
}

class OrderBuilder {
    state: string = "Placed";

    public prepareOrder(): OrderBuilder {
        if (this.state === "Placed") {
            this.state = "Prepared";
        }
        return this;
    }

    public deliverOrder(): OrderBuilder {
        if (this.state === "Prepared") {
            this.state = "Delivered";
        }
        return this;
    }

    public build(): Order {
        return new Order(this);
    }
}

// Usage
const completedOrder = Order.Builder
    .prepareOrder()
    .deliverOrder()
    .build();
console.log(completedOrder.getState()); // "Delivered"

Supporting multiple representations of the same object:

class Clothing {
    type: string;
    fabric: string;
    color: string;
    brand: string;

    private constructor(builder: ClothingBuilder) {
        this.type = builder.type;
        this.fabric = builder.fabric;
        this.color = builder.color;
        this.brand = builder.brand;
    }

    public static get Builder() {
        return new ClothingBuilder();
    }
}

class ClothingBuilder {
    type!: string;
    fabric!: string;
    color!: string;
    brand!: string;

    public setType(type: string): ClothingBuilder {
        this.type = type;
        return this;
    }

    public setFabric(fabric: string): ClothingBuilder {
        this.fabric = fabric;
        return this;
    }

    public setColor(color: string): ClothingBuilder {
        this.color = color;
        return this;
    }

    public setBrand(brand: string): ClothingBuilder {
        this.brand = brand;
        return this;
    }

    public build(): Clothing {
        return new Clothing(this);
    }
}

// Usage
const tShirt = Clothing.Builder
    .setType("T-Shirt")
    .setFabric("Cotton")
    .setColor("Blue")
    .setBrand("BrandA")
    .build();

const pants = Clothing.Builder
    .setType("Pants")
    .setFabric("Denim")
    .setColor("Black")
    .setBrand("BrandB")
    .build();

Why this pattern is so important?

The Builder Design Pattern is important for several key reasons, especially when it comes to managing the complexity of object creation. Here's why it's so valuable:

Handling Complex Objects

When an object has many attributes, some of which may be optional or need to be set in a specific order, the Builder Pattern provides a clear and structured way to create the object.

Improves Code Readability and Maintainability

By separating the object creation logic from the object itself, the Builder Pattern makes the code more readable and easier to maintain.

Reduces Constructor Overloading

Instead of having multiple constructors with different combinations of parameters, the Builder Pattern eliminates the need for constructor overloading.

Clear Separation of Concerns

The builder separates the construction of an object from its representation. This means that you can change how the object is constructed without affecting its representation, or vice versa.

Conclusion

The Builder Design Pattern is an essential tool for developers dealing with complex object creation. By breaking down the construction process into clear, manageable steps, it improves code readability, maintainability, and flexibility. Whether you're working with objects that have many attributes, require multi-step construction, or need to support multiple configurations, the Builder Pattern provides an elegant solution that prevents over-complicated constructors and reduces errors.

The blog covered:

What is the Builder Pattern?
When you should use it?
Real-World Examples of Builder Use
Why this pattern is so important?

How to Implement the Singleton Design Pattern

Houda-DE — Sun, 10 Nov 2024 18:12:19 +0000

Introduction

Recently, while working on a Next.js application and connecting to my database, I made the mistake of not having a single connection point to the database. As a result, the database was instantiated multiple times — if I remember correctly, about five instances within the same app. My computer started to heat up, becoming less efficient, and I began to see strange errors when handling entities. After much thought, I realized that the issue was due to the multiple instances created to connect to the database. So, how can I avoid this problem in the future — and help you avoid it too?

To solve this problem, after a lot of research into how the community addressed it, I discovered the perfect solution: the Singleton creation pattern. Singleton ensures that a class A can only be instantiated once and that this single instance is shared across the entire application — providing a single connection point to the database. This approach avoids any risk of duplication and system overload.

In this article, we will explore how the Singleton works, why it is so effective in situations where a single instance is needed, and how to implement it correctly to avoid similar errors in the future.

Sections We Will Cover

What is the Singleton Pattern?
How to Implement the Singleton
Real-World Examples of Singleton Use
Why is the Singleton Design Pattern so Important
Conclusion ## What is the Singleton Pattern? The Singleton design pattern is one of the five creation patterns introduced by the Gang of Four in their book "Design Patterns: Elements of Reusable Object-Oriented Software". It ensures that a class cannot be instantiated more than once in an application, meaning that the instance is shared throughout the application. This is useful in cases where resources are shared, such as the database connection issue I encountered personally, or any centralized configuration.

By limiting the number of instances to one, Singleton helps avoid duplication and better manage resources, thereby reducing the risk of overload and inconsistencies in the application.

How to Implement the Singleton

After examining the issue of ensuring that there is only one unique instance for a given class and having a single global access point to that instance, the potential solution lies in using the Singleton design pattern. Now, let's look at the logic we will use to implement this optimal solution:

Define a Static Variable for the Instance

The first step is to declare a private static variable that will hold the unique instance of the class.
Protect the Constructor

The class constructor must be made private so that other classes cannot instantiate the class directly.

here is the class diagram exemple to clarify:

and here is the implementation in typescript :

class DatabaseConnection {
  // Step 1: Declare a static private instance
  private static instance: DatabaseConnection;

  // Private variable to hold the database connection
  private connection: string;

  // Step 2: Private constructor to prevent direct instantiation
  private constructor() {
    // Simulate establishing a database connection
    this.connection = 'Database connection established!';
    console.log(this.connection);
  }

  // Step 3: Public static method to get the single instance
  public static getInstance(): DatabaseConnection {
    if (!DatabaseConnection.instance) {
      DatabaseConnection.instance = new DatabaseConnection();
    }
    return DatabaseConnection.instance;
  }

  // You can add other methods
}

Now let's create instances and see what will happen:

const db1 = DatabaseConnection.getInstance(); 
const db2 = DatabaseConnection.getInstance(); 
console.log(db1 === db2);

let's see now what will be printed in the console:

It printed true, confirming that the DatabaseConnection class was instantiated only once.

Why is the Singleton Design Pattern so Important

The Singleton Design Pattern is crucial for avoiding several future issues, including:

Ensures a Single Instance

It guarantees that a class has only one instance throughout the entire application, which is vital for shared resources like configurations or database connections. Multiple instances can lead to inconsistencies or excessive resource consumption.
Global Access to the Instance

The Singleton pattern provides global access to the instance, allowing all parts of the application to interact with the same object, ensuring consistency across the entire application.
Resource Management

Creating a new instance every time can be costly in terms of memory and performance. The Singleton ensures only one instance is created, reducing overhead, for example, with a database connection.
Prevents Redundant Work

When multiple components need access to the same resource, the Singleton ensures only one instance is used, optimizing resource utilization.

Conclusion

In this blog, we discussed a problem I faced while working on a Next.js application, where multiple instances of the database connection were created, leading to system inefficiency and strange errors. The solution I found to this problem was the Singleton Design Pattern, which ensures that a class can only be instantiated once, providing a single, shared instance throughout the entire application. This pattern helps avoid redundancy, resource overload, and inconsistencies by maintaining centralized control.

The blog covered:

What the Singleton Pattern is:
How to Implement the Singleton:
Why the Singleton is Important:
Real-World Examples: