Generic repository pattern in Typescript - Mini Project: Build & Apply

Generic Repository Pattern in TypeScript

📖 Scenario: You are building a simple data management system for different types of items like books and movies. To keep your code clean and reusable, you want to create a generic repository that can handle basic operations for any type of item.

🎯 Goal: Build a generic repository class in TypeScript that can store, add, and retrieve items of any type. Then use it to manage a collection of books.

📋 What You'll Learn

Create a generic repository class with methods to add and get all items

Use a generic type parameter to allow storing any type of item

Create a Book interface with title and author properties

Create an instance of the repository for books and add some books

Print the list of books stored in the repository

💡 Why This Matters

🌍 Real World

Generic repositories are used in software to manage data storage and retrieval in a consistent way, no matter what kind of data you have.

💼 Career

Understanding generic patterns and TypeScript generics is important for writing scalable and maintainable code in many professional web development jobs.

1

Create the Book interface

Create an interface called Book with two string properties: title and author.

Typescript

// Your code here

Need a hint?

Use the interface keyword to define the shape of a book object.

2

Create the generic Repository class

Create a generic class called Repository with a type parameter T. Inside, create a private array called items to store objects of type T. Initialize it as an empty array.

Typescript

interface Book {
  title: string;
  author: string;
}

// Your code here

Need a hint?

Use class Repository<T> and declare private items: T[] = []; inside it.

3

Add add and getAll methods to Repository

Inside the Repository class, add a method called add that takes a parameter item of type T and adds it to the items array. Also add a method called getAll that returns the array of items.

Typescript

interface Book {
  title: string;
  author: string;
}

class Repository {
  private items: T[] = [];

  // Your code here
}

Need a hint?

Define add(item: T): void to push item into items. Define getAll(): T[] to return items.

4

Use Repository with Book and print all books

Create a variable called bookRepo as a new Repository<Book>. Add two books to bookRepo using the add method with these exact values: { title: "1984", author: "George Orwell" } and { title: "The Hobbit", author: "J.R.R. Tolkien" }. Then print the result of bookRepo.getAll() using console.log.

Typescript

interface Book {
  title: string;
  author: string;
}

class Repository {
  private items: T[] = [];

  add(item: T): void {
    this.items.push(item);
  }

  getAll(): T[] {
    return this.items;
  }
}

// Your code here

Need a hint?

Create bookRepo as new Repository<Book>(). Use add twice with the exact book objects. Print with console.log(bookRepo.getAll()).