2016/02/07 - Apache Onami has been retired.

Welcome to Apache Onami-Validation!

Apache Onami-Validation is a Java5 compatible JSR303 (Bean Validation) integration extension for Google Guice, using http://bval.apache.org/ provider implementation.

That module has multiple purposes, such as:

• obtain javax.validation.ConstraintValidator instances using the Google Guice Injector to easily support DI;
• easily inject the javax.validation.Validator reference into components that require it;
• easily intercept methods and validate method arguments.

Before starting

Apache Onami-Validation is available on the Maven Central repo, you just need to add the dependency below in your pom.xml file:

<dependencies>
  ...
  <dependency>
    <groupId>org.apache.onami</groupId>
    <artifactId>org.apache.onami.validation</artifactId>
    <version>1.0.1-SNAPSHOT</version>
  </dependency>
  ...
</dependencies>

Bootstrap

Simply, the org.apache.onami.validation.ValidationModule is the Google Guice module that bootstraps Apache BVal. All users have to do is add this module when creating the Google Guice Injector:

import com.google.inject.Guice;
import com.google.inject.Injector;

import org.apache.onami.validation.ValidationModule;

Injector injector = Guice.createInjector([...],
    new ValidationModule(),
    [...]
);

Obtain javax.validation.ConstraintValidator instances

Users can now implement javax.validation.ConstraintValidator classes that require Dependency Injection by Google Guice:

import javax.validation.ConstraintValidator;

public class MyCustomValidator
    implements ConstraintValidator<MyAssert, MyType>
{

    private final MyExternalService service;

    @javax.inject.Inject
    public MyCustomValidator( MyExternalService service )
    {
        this.service = service;
    }

    public void initialize( MyAssert annotation )
    {
        // do something
    }

    public boolean isValid( MyType value, ConstraintValidatorContext context )
    {
        return value == null || service.doSomething( value );
    }

}

Don't forget to bind the MyExternalService class in the Google Guice Binder!!!

Inject the javax.validation.Validator reference

Clients can easily inject javax.validation.Validator instances into their custom components just marking it using @Inject annotation:

import javax.validation.Validator;

public class MyValidatorClient
{

    @Inject
    private Validator validator;

    public void setValidator( Validator validator )
    {
       this.validator = validator;
    }

    // ...

}

When obtaining MyValidatorClient instances from the Injector, the javax.validation.Validator will be automagically bound.

Intercept methods and validate method arguments

Taking advantage of the Apache BVal extension to validate method arguments, the ValidationModule comes with an AOP interceptor, automatically initialized in the org.apache.onami.validation.ValidationModule, that makes easy method arguments validation.

All users have to do is annotate interested methods with org.apache.onami.validation.Validate annotation, then annotate arguments with constraints, as follows below:

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

import org.apache.onami.validation.Validate;

public class MyService
{

    @Validate( groups = { MyGroup.class }, validateReturnedValue = true )
    public Country insertCountry( @NotNull(groups = { MyGroup.class })
                                  String name,
                                  @NotNull(groups = { MyGroup.class })
                                  @Size(max = 2, groups = { MyGroup.class, MyOtherGroup.class })
                                  String iso2Code,
                                  @NotNull(groups = { MyGroup.class })
                                  @Size(max = 3, groups = { MyGroup.class, MyOtherGroup.class })
                                  String iso3Code )
    {
        return ...;
    }

}

The @Validate annotation supports following arguments:

• groups Class array, by default, that specifies the groups to be validated;
• validateReturnedValue flag, false by default, indicating whether the method's return value should be validated.

class DummyException
    extends Exception
{

    public DummyException( Throwable cause )
    {
        super( cause );
    }

    public DummyException( String message, Throwable cause )
    {
        super( message, cause );
    }

}

import javax.validation.constraints.NotNull;

import org.apache.onami.validation.Validate;

public class MyService
{

    @Validate( rethrowExceptionsAs = DummyException.class )
    public Country retrieve( @NotNull String name )
    {
        return ...;
    }

}

import javax.validation.constraints.NotNull;

import org.apache.onami.validation.Validate;

public class MyService
{

    @Validate( exceptionMessage = "This is just a dummy message %s", rethrowExceptionsAs = DummyException.class )
    public Country retrieve( @NotNull String name )
    {
        return ...;
    }

}