Java Practical Course. Spring IoC

‘ToDo List’ Application

'To-Do List' Application

Objective

Develop the Service Layer for a "To-Do List" Application that manages Users, To-Do Lists, and Tasks using natural keys (e.g., unique attributes like email for Users, titles for To-Do Lists and Tasks) instead of synthetic IDs. The implementation must follow the Inversion of Control (IoC) principle to manage dependencies, include comprehensive testing, and ensure proper model-level encapsulation.

Requirements

The Service Layer of the "To-Do List" Application must support the following operations, using natural keys for identification:

User Management:

• Create: Add a new User to the application, identified by a unique natural key (e.g., email address).
• Read: Retrieve details of existing Users (e.g., by email or as a list of all Users).
• Update: Modify details of an existing User identified by their natural key (e.g., update name or other attributes).
• Delete: Remove an existing User identified by their natural key.

To-Do List Management:

• Create: Add a new To-Do List for an existing User, identified by a unique natural key (e.g., a combination of User’s email and To-Do List title).
• Read: Retrieve details of existing To-Do Lists (e.g., by User’s email and To-Do List title, or all lists for a User).
• Update: Modify details of an existing To-Do List identified by its natural key (e.g., update description).
• Delete: Remove an existing To-Do List identified by its natural key.

Task Management:

• Create: Add a new Task to an existing To-Do List, identified by a unique natural key (e.g., a combination of To-Do List’s natural key and Task title).
• Read: Retrieve details of existing Tasks (e.g., by To-Do List’s natural key and Task title, or all Tasks in a list).
• Update: Modify details of an existing Task identified by its natural key (e.g., update status or due date).
• Delete: Remove an existing Task identified by its natural key.

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Additional Requirements

Natural Keys:

Use natural keys for all entities instead of synthetic IDs:

• User: Email address (e.g., user@example.com).
• To-Do List: Combination of User’s email and To-Do List title (e.g., user@example.com:Daily Tasks).
• Task: Combination of To-Do List’s natural key and Task title (e.g., user@example.com:Daily Tasks:Buy Groceries).

✅ Ensure uniqueness of natural keys within their respective scopes (e.g., a User cannot have two To-Do Lists with the same title).

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Inversion of Control (IoC):

• Implement the Service Layer using IoC principles (e.g., dependency injection) to manage dependencies between components.
• Avoid hard-coded dependencies; instead, inject dependencies (e.g., UserService, ToDoListService, TaskService) via constructors or a dependency injection framework (e.g., Spring IoC, Guice).

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Model Layer:

• Implement all necessary getters and setters for the model classes (User, ToDoList, Task) to ensure proper encapsulation and data access.
• Ensure model classes store natural keys appropriately (e.g., User has an email field, ToDoList references the User’s email and its own title).

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Service Layer:

• Maintain a list of all Users as a field in the UserService class (e.g., as a List<User> or a Map<String, User> where the key is the email).
• Ensure services (UserService, ToDoListService, TaskService) interact using natural keys for lookups and operations.

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Testing:

• Write unit tests for all CRUD operations (User, To-Do List, Task) using natural keys.
• Mock dependencies where necessary to align with IoC principles (e.g., using a mocking framework like Mockito if using Java).
• Execute the tests to demonstrate the correct functionality of the Service Layer code.

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📌 Note: Save a list of all Users as a field in the UserService class.