How to create a validator restrictions for more fields through annotation in spring 4.* for example
@UniqueValidator
@Entity @Table(name = "persons") @UniqueValidator(message="Peson already exist",columns={"name","lastName"}) public class { @Column private String name; @Column private String lastName; } roughly speaking..
select ... from persons where name='qwerty' and lastName='asdfgh' Here's one way to do it in Spring MVC and JSR 303 validation:
Create a constraint annotation:
package com.awgtek.model.validation; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; import javax.validation.Constraint; import javax.validation.Payload; /** * The target field should be unique in the data store. */ @Documented @Constraint(validatedBy = UniqueNameValidator.class) @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface UniqueName { /** * @return the error message template */ String message() default "{com.awgtek.model.validation.UniqueName.message}"; /** * @return the groups the constraint belongs to */ Class<?>[] groups() default {}; /** * @return the payload associated to the constraint */ Class<? extends Payload>[] payload() default {}; /** * @return a class an instance of which will be used to check the existence of a name. */ Class<? extends NameExistenceChecker> nameExistenceChecker(); } Apply this annotation at the class level to the model class:
package com.awgtek.model; import com.awgtek.model.validation.MyNameExistenceChecker; import com.awgtek.model.validation.UniqueName; import com.awgtek.model.validation.UniqueNameConstraint; @UniqueName(groups = UniqueNameConstraint.class, nameExistenceChecker = MyNameExistenceChecker.class) public class ConfigurationAttribute { private String name; private String lastName; // getters and setters omitted } The UniqueNameValidator:
package com.awgtek.model.validation; import com.awgtek.service.MyService; import javax.inject.Inject; import javax.validation.ConstraintValidator; import javax.validation.ConstraintValidatorContext; public class UniqueNameValidator implements ConstraintValidator<UniqueName, Object> { @Inject private NameExistenceCheckerFactory nameExistenceCheckerFactory; private NameExistenceChecker nameExistenceChecker; @Override public void initialize(UniqueName constraintAnnotation) { nameExistenceChecker = nameExistenceCheckerFactory.get(constraintAnnotation.nameExistenceChecker()); } @Override public boolean isValid(Object value, ConstraintValidatorContext context) { return !nameExistenceChecker.nameExists(value); } } The UniqueNameValidator then depends on a couple of classes:
package com.awgtek.model.validation; import javax.inject.Inject; import org.springframework.stereotype.Component; @Component public class NameExistenceCheckerFactory { @Inject private NamespaceNameExistenceChecker namespaceNameExistenceChecker; @Inject private MyNameExistenceChecker myNameExistenceChecker; public NameExistenceChecker get(Class<? extends NameExistenceChecker> clazz) { if (clazz.equals(MyNameExistenceChecker.class)) { return myNameExistenceChecker; } throw new IllegalStateException("Unknown NameExistenceChecker"); } } package com.awgtek.model.validation; public interface NameExistenceChecker { boolean nameExists(Object objectWithName); } The implementation class that actually looks up whether the item exists in the database (via a service):
package com.awgtek.model.validation; import com.awgtek.model.MyModelClass; import com.awgtek.service.MyService; import javax.inject.Inject; import org.springframework.stereotype.Component; @Component public class AttributeNameExistenceChecker implements NameExistenceChecker { @Inject private MyService myService; @Override public boolean nameExists(Object objectWithName) { MyModelClass myObject = (MyModelClass) objectWithName; return myService.itemAlreadyExists(myObject.getName(), myObject.getLastName()); } }