Real-word examples of Entities in Domain Driven Design

Here are some real-world examples of entities in domain-driven design:

1. E-commerce:
   • Product: Represents a tangible or digital item available for purchase. It has attributes like name, description, price, and stock quantity.
   • Customer: Represents an individual or organization that can browse and make purchases on the e-commerce platform. It typically has attributes like name, email, and shipping address.
   • Order: Represents a customer's request to purchase one or more products. It contains information like order number, customer, and order status.
   • OrderItem: Represents an individual item within an order, including the product, quantity, and price.
   • ShoppingCart: Represents a temporary storage of products that a customer is interested in purchasing before finalizing the order.

class Product {
    String productId;
    String name;
    String description;
    double price;
    int stockQuantity;
}

class Customer {
    String customerId;
    String name;
    String email;
    String shippingAddress;
}

class Order {
    String orderId;
    Customer customer;
    List<OrderItem> orderItems;
    String status;
}

class OrderItem {
    Product product;
    int quantity;
    double price;
}

class ShoppingCart {
    Customer customer;
    List<Product> products;
}

2. Banking:
   • Account: Represents a customer's bank account, such as savings or checking. It has a unique account number and properties like balance, owner, and transaction history.
   • Customer: Represents an individual or organization that has an account with the bank. It includes information like name, contact details, and accounts owned.
   • Transaction: Represents a financial transaction that affects one or more accounts. It includes details like transaction ID, amount, date, and the involved accounts.

class Account {
    String accountId;
    Customer customer;
    double balance;
    List<Transaction> transactions;
}

class Customer {
    String customerId;
    String name;
    List<Account> accounts;
}

class Transaction {
    String transactionId;
    Date date;
    double amount;
    Account fromAccount;
    Account toAccount;
}

3. Healthcare:
   • Patient: Represents an individual who receives medical care. It has attributes like patient ID, name, date of birth, and medical history.
   • Appointment: Represents a scheduled meeting between a patient and a healthcare provider. It includes details like appointment date, time, patient, and provider.
   • Procedure: Represents a medical procedure or treatment that a patient undergoes. It includes information such as the procedure code, description, and date.

class Patient {
    String patientId;
    String name;
    Date dateOfBirth;
    List<Appointment> appointments;
    List<Procedure> procedures;
}

class Appointment {
    String appointmentId;
    Date dateTime;
    Patient patient;
    Doctor doctor;
}

class Procedure {
    String procedureCode;
    String description;
    Date date;
    Patient patient;
}

4. Social Media:
   • User: Represents an individual using the social media platform. It includes information like username, profile details, and a list of posts and comments associated with the user.
   • Post: Represents a user's content shared on the platform, such as text, images, or videos. It includes attributes like post ID, content, and timestamp.
   • Comment: Represents a user's response to a post. It includes information like comment ID, content, and the user who made the comment.

class User {
    String userId;
    String username;
    String profileDetails;
    List<Post> posts;
    List<Comment> comments;
}

class Post {
    String postId;
    String content;
    Date timestamp;
    User user;
}

class Comment {
    String commentId;
    String content;
    Date timestamp;
    User user;
}

5. Education:
   • Student: Represents an individual enrolled in an educational institution. It includes attributes like student ID, name, contact information, and enrollment status.
   • Course: Represents an academic course offered by the institution. It includes details like course code, title, instructor, and a list of enrolled students.
   • Enrollment: Represents a student's registration in a specific course. It contains information like enrollment ID, student, course, and enrollment status.

class Student {
    String studentId;
    String name;
    String contactInfo;
    List<Enrollment> enrollments;
}

class Course {
    String courseId;
    String title;
    String instructor;
    List<Student> enrolledStudents;
}

class Enrollment {
    String enrollmentId;
    Student student;
    Course course;
    String status;
}

These entities are central to their respective domains and play a key role in modeling and managing the domain's core concepts and data.