Request & Response Validation

When building REST APIs, clients send data to your server. This data often needs to meet certain rules, like a field not being empty, or a number being within a specific range.

• Data Integrity: Ensures your database stores only valid information.
• Security: Prevents malicious or malformed data from causing issues.
• User Experience: Provides clear, immediate feedback to clients when their input is incorrect.

Validation is crucial for robust and reliable APIs.

Spring Boot makes data validation easy by integrating with the Jakarta Bean Validation API (JSR 380). You'll primarily use the @Valid annotation in your controller methods.

Common validation annotations include:

• @NotNull: Field must not be null.
• @NotBlank: String must not be null and must contain at least one non-whitespace character.
• @Size(min=X, max=Y): String or collection size must be within range.
• @Min(X), @Max(Y): Numeric value must be within range.
• @Email: String must be a valid email format.