Cascaded bean validation 2.0 not working with nested object inside Map

Theiaz :

Although, this question has been answered I'm interested why @Validated is needed for a working cascaded validation of Map<String, @Valid Employee>.

Update 2: For some deeper understanding I've found those posts (One,Two and Three), which explains, that @Validated is neeeded to activate method level validation. With the help of this, collections can be validated, due they are no JavaBeans which are validated instead (JSR 303).

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Solution: I've updated my code snippets and my repository with working code examples. All I have to do is to annotate my controller with @Validated and add some getters in Employee. MethodValidationPostProcessor is not necessary at all.

Update: I've updated my question and forked Spring Boot Rest example to add a minimal Rest API to demonstrate:

Github Repo. The example values are inside README.md!

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I've got an Spring Boot 2 API to store some employees. I can pass either one Employee or either a Map<String, Employee>.

@Validated //this is the solution to activate map validation
@RestController
class EmployeeController {

  @PostMapping("/employees")
  List<Employee> newEmployee(@RequestBody @Valid Employee newEmployee) {
     ...
  }

  @PostMapping("/employees/bulk")
  List<Employee> newEmployee(@RequestBody Map<String, @Valid Employee> 
  newEmployees) {
     ...
  }
}

Employee exists of some inner static classes which also needs to be validated:

public class Employee {

    @NotBlank
    public final String name;
    @Valid
    public final EmployeeRole role;

    @JsonCreator
    public Employee(@JsonProperty("name") String name,
        @JsonProperty("role") EmployeeRole role) {

        this.name = name;
        this.role = role;
    }

    // getters

    public static class EmployeeRole {

        @NotBlank
        public String rolename;

        @Min(0)
        public int rating;

        @JsonCreator
        public EmployeeRole(@JsonProperty("rolename") String rolename,
            @JsonProperty("rating") int rating) {

            this.rolename = rolename;
            this.rating = rating;
        }

        // getters
    }
}

For now, validation for single requests are working but not for my bulk requests. As far as i know this should be possible with Bean validation 2.0.

Do you know what I've did wrong? Do i need to write a custom validator?

oleg.cherednik :

To make it working you have to do following:

Add MethodValidationPostProcessor bean to configuration

@Bean
public MethodValidationPostProcessor methodValidationPostProcessor() {
    return new MethodValidationPostProcessor();
}

Add @Validated to your EmployeeController

@Validated
@RestController
public class EmployeeController {}'

Add @Valid to Map or to Employee

public List<Employee> newEmployee(@RequestBody @Valid Map<String, Employee> newEmployees) {}   
public List<Employee> newEmployee(@RequestBody Map<String, @Valid Employee> newEmployees) {}

That's all. This is entire EmployeeController:

@Validated
@RestController
public class EmployeeController {

    @PostMapping("/employees")
    public List<Employee> newEmployee(@RequestBody @Valid Employee newEmployee) {
        return Collections.singletonList(newEmployee);
    }

    @PostMapping("/employees/bulk")
    public List<Employee> newEmployee(@RequestBody @Valid Map<String, Employee> newEmployees) {
        return new ArrayList<>(newEmployees.values());
    }
}

And SpringBoot configuration file

@SpringBootApplication
public class Application extends SpringBootServletInitializer {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {
        return new MethodValidationPostProcessor();
    }

}

Hope it help you.