Learnitweb

Author: Editorial Team

  • Explain a scenario where you would use entity listeners in JPA

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    Entity listeners in JPA are used to react to lifecycle events of entities, such as creation, update, or deletion. They allow you to execute logic automatically whenever certain events occur, without polluting your service or repository layer with repetitive code. Here’s a detailed explanation with a scenario: 1. What Are Entity Listeners 2. Scenario: Audit…

  • How would you audit entity creation and update times automatically?

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    In Spring Boot with JPA/Hibernate, you can automatically track entity creation and update timestamps by using JPA auditing. This allows you to maintain fields like createdAt and updatedAt without manually setting them in every service method. Here’s a detailed guide: 1. Enable JPA Auditing In your Spring Boot application, enable auditing by adding @EnableJpaAuditing to…

  • What’s the impact of @Transactional(readOnly = true) in a method?

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    In Spring, @Transactional(readOnly = true) is used to optimize transactions that only perform read operations. It has several effects on the transaction behavior, the persistence context, and the database interaction. Here’s a detailed explanation: 1. Primary Purpose 2. Impact on Hibernate / JPA When using Hibernate with Spring: 3. Impact on the Database 4. Behavior…

  • Optimistic locking using Spring Boot and JPA Hibernate

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    Optimistic locking is a concurrency control strategy used in applications (including Spring Boot + JPA/Hibernate) to prevent lost updates when multiple transactions try to update the same record without using database-level locks. Unlike pessimistic locking, it assumes conflicts are rare and checks for conflicts only at the time of commit. Here’s a detailed explanation: 1.…

  • Create a custom starter in Spring Boot

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    Creating a custom Spring Boot starter is a powerful way to package reusable configuration, dependencies, and auto-configuration logic into a single module. This is especially useful when you want to apply common setups across multiple Spring Boot projects in your organization or team. What Is a Spring Boot Starter? A starter is a special kind…

  • Set different logging levels for specific packages in Spring Boot

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    To set different logging levels for specific packages in a Spring Boot application, you can configure them using the application.properties or application.yml file. This allows you to control how much logging detail you get per package (e.g., your own code, Spring internals, Hibernate, etc.), which is useful for debugging specific modules without cluttering the logs.…

  • Expose Custom Metrics

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    To expose custom metrics in Spring Boot, you can use Micrometer, which is the metrics collection facade integrated into Spring Boot Actuator. Spring Boot Actuator provides production-ready endpoints like /actuator/metrics, and you can extend it with custom metrics to track application-specific behavior. Step-by-Step Guide to Expose Custom Metrics 1. Add Required Dependencies If you’re using…

  • Application versioning in a Spring Boot API

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    Implementing application versioning in a Spring Boot REST API is crucial for supporting backward compatibility when your API evolves. There are several strategies to version a Spring Boot API, and the method you choose depends on your design goals and client needs. Common Strategies for API Versioning 1. URI Path Versioning (Recommended) Most widely used…

  • Run specific logic right after Spring Boot application startup

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    To run specific logic right after your Spring Boot application starts, you can use one of the following standard interfaces provided by Spring: 1. Using CommandLineRunner Example: 2. Using ApplicationRunner Example: 3. Using @EventListener(ApplicationReadyEvent.class) Example: When to Use Which? Use Case Recommended Interface Need command-line arguments CommandLineRunner or ApplicationRunner Need to execute logic after Spring…

  • Custom error message when validation fails

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    To make your Spring Boot REST API return custom error messages when validation fails, you need to: Step-by-Step Guide Step 1: Add Validation Dependency If you’re using Maven, make sure you have this in your pom.xml: Or for older versions: Step 2: Annotate Your Request DTO Example DTO with validation annotations: Step 3: Use @Valid…