6.4 Validation Groups

Use Validation Groups when create and update need different rules (e.g. no id on create, required id on update).

Reference: Bean Validation (JSR 380), Spring

1. Group Interfaces

public interface CreateGroup {}
public interface UpdateGroup {}

• These are empty interfaces used as markers.

2. Assign Groups on Entity/DTO

@Getter
@Setter
public class MemberDto {

    @NotNull(groups = UpdateGroup.class)
    private Long id;

    @NotBlank(groups = { CreateGroup.class, UpdateGroup.class })
    private String name;

    @NotBlank(groups = CreateGroup.class)
    @Size(min = 8, groups = CreateGroup.class)
    private String password;

    @Email(groups = { CreateGroup.class, UpdateGroup.class })
    private String email;
}

• groups: Groups the constraint applies to. The same constraint can be applied to multiple groups.
• id required only for UpdateGroup, password required only for CreateGroup, etc.

3. @Validated(Group.class) in Controller

@PostMapping
public ResponseEntity<MemberDto> create(@Validated(CreateGroup.class) @RequestBody MemberDto dto) {
    return ResponseEntity.ok(memberService.create(dto));
}

@PutMapping("/{id}")
public ResponseEntity<MemberDto> update(
        @PathVariable Long id,
        @Validated(UpdateGroup.class) @RequestBody MemberDto dto) {
    dto.setId(id);
    return ResponseEntity.ok(memberService.update(dto));
}

• @Validated(Group.class) specifies "validate only this group for this request".
• @Valid does not specify a group and only activates constraints with no groups specified.

4. GroupSequence

Validate groups in order using @GroupSequence.

@GroupSequence({ FirstCheck.class, SecondCheck.class, MemberDto.class })
public interface OrderedChecks {}

public interface FirstCheck {}
public interface SecondCheck {}

• If FirstCheck fails, SecondCheck is not executed.

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tip

Alternatively, separate DTOs into CreateRequest and UpdateRequest with different validations for each. Groups are most useful when "one DTO serves multiple purposes".