303-frameworks-spring-boot-validation
Spring Boot Validation Guidelines
Apply Spring Boot validation best practices at API boundaries.
What is covered in this Skill?
- Bean Validation annotations on DTOs and command models
- @Valid / @Validated on controllers and method parameters
- Validation groups for create/update workflows
- Custom constraint annotations and validators
- Consistent 400 error responses for validation failures
Scope: Apply recommendations based on the reference rules and good/bad examples.
Constraints
Before applying validation changes, ensure the project compiles. After improvements, run full verification.
More from jabrena/cursor-rules-java
110-java-maven-best-practices
Use when you need to review, improve, or troubleshoot a Maven pom.xml file — including dependency management with BOMs, plugin configuration, version centralization, multi-module project structure, build profiles, or any situation where you want to align your Maven setup with industry best practices. This should trigger for requests such as Review pom.xml to improve it; Apply Maven best practices to pom.xml; Improve Maven POM configuration. Part of cursor-rules-java project
115121-java-object-oriented-design
Use when you need to review, improve, or refactor Java code for object-oriented design quality — including applying SOLID, DRY, and YAGNI principles, improving class and interface design, fixing OOP concept misuse (encapsulation, inheritance, polymorphism), identifying and resolving code smells (God Class, Feature Envy, Data Clumps), or improving object creation patterns, method design, and exception handling. This should trigger for requests such as Review Java code for object-oriented design; Refactor Java code for object-oriented design; Improve Java code for object-oriented design; Fix OOP concept misuse in Java code. Part of cursor-rules-java project
110124-java-secure-coding
Use when you need to apply Java secure coding best practices — including validating untrusted inputs, defending against injection attacks with parameterized queries, minimizing attack surface via least privilege, applying strong cryptographic algorithms, handling exceptions securely without exposing sensitive data, managing secrets at runtime, avoiding unsafe deserialization, and encoding output to prevent XSS. This should trigger for requests such as Review Java code for secure coding. Part of cursor-rules-java project
106111-java-maven-dependencies
Use when you need to add or evaluate Maven dependencies that improve code quality — including nullness annotations (JSpecify), static analysis (Error Prone + NullAway), functional programming (VAVR), or architecture testing (ArchUnit) — and want a consultative, question-driven approach that adds only what you actually need. This should trigger for requests such as Add Maven dependencies; Add JSpecify nullness dependencies; Add Error Prone NullAway dependencies; Add VAVR functional dependencies; Add ArchUnit architecture testing dependencies. Part of cursor-rules-java project
102128-java-generics
Use when you need to review, improve, or refactor Java code for generics quality — including avoiding raw types, applying the PECS (Producer Extends Consumer Super) principle for wildcards, using bounded type parameters, designing effective generic methods, leveraging the diamond operator, understanding type erasure implications, handling generic inheritance correctly, preventing heap pollution with @SafeVarargs, and integrating generics with modern Java features like Records, sealed types, and pattern matching. This should trigger for requests such as Improve the code with Generics; Apply Generics; Refactor the code with Generics. Part of cursor-rules-java project
101131-java-testing-unit-testing
Use when you need to review, improve, or write Java unit tests — including migrating from JUnit 4 to JUnit 5, adopting AssertJ for fluent assertions, structuring tests with Given-When-Then, ensuring test independence, applying parameterized tests, mocking dependencies with Mockito, verifying boundary conditions (RIGHT-BICEP, CORRECT, A-TRIP), leveraging JSpecify null-safety annotations, or eliminating testing anti-patterns such as reflection-based tests or shared mutable state. This should trigger for requests such as Review Java code for unit tests; Apply best practices for unit tests in Java code. Part of cursor-rules-java project
101