spring-boot-dependency-injection

What problem does it solve?

This Skill helps developers correctly implement and understand dependency injection (DI) in Spring Boot applications, ensuring maintainable, testable, and robust code.

Core Features & Use Cases

• Constructor Injection: Guides users to prioritize constructor injection for mandatory dependencies, promoting immutability and testability.
• Optional Dependencies: Demonstrates how to handle optional collaborators using setter injection or ObjectProvider.
• Bean Configuration & Resolution: Explains techniques like @Qualifier, @Primary, and conditional beans to manage complex wiring scenarios.
• Use Case: A developer is refactoring a legacy Spring service that uses field injection. This Skill provides clear patterns to migrate to constructor injection, making the service easier to unit test and understand.

Quick Start

Apply constructor injection to the UserService class by adding a constructor that accepts UserRepository and EmailService as parameters.