Spring Framework - Validation

Spring Framework - Validation

SPRING FRAMEWORK 3.0
Dmitry Noskov Validation, JSR-303

Spring Validation

Spring Framework - Validation Dmitry Noskov

Spring Validator
public interface Validator {

/** Can this instances of the supplied clazz */
boolean supports(Class<?> clazz);

/**
* Validate the supplied target object, which must be
* @param target the object that is to be validated
* @param errors contextual state about the validation process
*/
void validate(Object target, Errors errors);
}


Simple Spring validator
public class MakeValidator implements Validator {
public boolean supports(Class<?> c) {return Make.class.equals(c);}

public void validate(Object target, Errors errors) {
ValidationUtils.rejectIfEmpty(errors, "name", "er.required");
Make make = (Make)target;

if (make.getName().length()<3) {
errors.rejectValue("name", "er.minlength");
} else if (make.getName().length()>20) {
errors.rejectValue("name", "er.maxlength");
}
}
}


Auxiliary classes
 Errors
 reject
 rejectValue

 ValidationUtils
 rejectIfEmpty
 rejectIfEmptyOrWhitespace

 invokeValidator


Resolving codes
 will create message codes for an object error
 code + "." + object name
 code

 will create message codes for a field
 code + "." + object name + "." + field
 code + "." + field

 code + "." + field type

 code


JSR-303
a specification for Bean Validation


Old validation solution


DDD with JSR-303


Fundamentals

Annotation

Constraint
Message Validator Validator

Constraint
Violation


Constraints
 applicable to class, method, field
 custom constraints
 composition
 object graphs
 properties:
 message
 groups

 payload


Standard constraints
Annotation Type Description
@Min(10) Number must be higher or equal
@Max(10) Number must be lower or equal
@AssertTrue Boolean must be true, null is valid
@AssertFalse Boolean must be false, null is valid
@NotNull any must not be null
@NotEmpty String / Collection’s must be not null or empty
@NotBlank String @NotEmpty and whitespaces ignored
@Size(min,max) String / Collection’s must be between boundaries
@Past Date / Calendar must be in the past
@Future Date / Calendar must be in the future
@Pattern String must math the regular expression


Example

public class Make {

@Size(min = 3, max = 20)
private String name;

@Size(max = 200)
private String description;
}


Validator methods

public interface Validator {
/** Validates all constraints on object. */
validate(T object, Class<?>... groups)

/** Validates all constraints placed on the property of object
*/
validateProperty(T object, String pName, Class<?>... groups)

/** Validates all constraints placed on the property
* of the class beanType would the property value */
validateValue(Class<T> type, String pName, Object val,
Class<?>…)
}


ConstraintViolation
 exposes constraint violation context
 core methods
 getMessage
 getRootBean

 getLeafBean

 getPropertyPath

 getInvalidValue


Validating groups
 separate validating
 simple interfaces for grouping
 inheritance by standard java inheritance
 composition
 combining by @GroupSequence


Grouping(1)
 grouping interface
public interface MandatoryFieldCheck {
}

 using
public class Car {
@Size(min = 3, max = 20, groups = MandatoryFieldCheck.class)

@Size(max = 20)
private String color;
}


Grouping(2)
 grouping sequence
@GroupSequence(Default.class, MandatoryFieldCheck.class)
public interface CarChecks {
}

 using
javax.validation.Validator validator;
validator.validate(make, CarChecks.class);


Composition
 annotation
@NotNull
@CapitalLetter
@Size(min = 2, max = 14)
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ METHOD, FIELD, ANNOTATION_TYPE })
public @interface CarNameConstraint {
}

 using
@CarNameConstraint


Custom constraint
 create annotation
@Constraint(validatedBy=CapitalLetterValidator.class)
public @interface CapitalLetter {
String message() default "{carbase.error.capital}";

 implement constraint validator
public class CapitalLetterValidator implements
ConstraintValidator<CapitalLetter, String> {

 define a default error message
carbase.error.capital=The name must begin with a capital letter


LocalValidatorFactoryBean

Spring JSR-303
Validator Validator

Spring
Adapter

Configuration
 define bean
<bean id="validator"

class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean"/>
or
<mvc:annotation-driven/>

 injecting
@Autowired
private javax.validation.Validator validator;
or
@Autowired
private org.springframework.validation.Validator validator;


Information
 JSR-303 reference
 http://docs.jboss.org/hibernate/validator/4.2/reference/en-US/html/
 http://static.springsource.org/spring/docs/3.0.x/spring-framework-
reference/html/validation.html
 samples
 http://src.springsource.org/svn/spring-samples/mvc-showcase
 blog
 http://blog.springsource.com/category/web/
 forum
 http://forum.springsource.org/forumdisplay.php?f=25


Questions


The end

http://www.linkedin.com/in/noskovd

http://www.slideshare.net/analizator/presentations

Spring Framework - Validation

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