# Bean Validation

## Bean Validation Component

Available as of Apache Camel 2.3

The Validation component performs bean validation of the message body using the Java Bean Validation API (JSR 303). Apache Camel uses the reference implementation, which is Hibernate Validator.

Maven users will need to add the following dependency to their `pom.xml` for this component:

    <dependency>
        <groupId>org.apache.camel</groupId>
        <artifactId>camel-bean-validator</artifactId>
        <version>x.x.x</version>
        <!-- use the same version as your Camel core version -->
    </dependency>

## URI format

    bean-validator:something[?options]

or

    bean-validator://something[?options]

Where something must be present to provide a valid URL. You can append query options to the URI in the following format, `?option=value&option=value&...`

## URI Options

The following URI options are supported:

Option | Default | Description
--- | --- | ---
`group` | `javax.validation.groups.Default` | The custom validation group to use.
`messageInterpolator` | `org.hibernate.validator.engine. ResourceBundleMessageInterpolator` | Reference to a custom `javax.validation.MessageInterpolator` in the Registry.
`traversableResolver` | `org.hibernate.validator.engine.resolver. DefaultTraversableResolver` | Reference to a custom `javax.validation.TraversableResolver` in the Registry.
`constraintValidatorFactory` | `org.hibernate.validator.engine. ConstraintValidatorFactoryImpl` | Reference to a custom `javax.validation.ConstraintValidatorFactory` in the Registry.

## Example

Assumed we have a java bean with the following annotations

| Car.java
    // Java
    public class Car {

        @NotNull
        private String manufacturer;

        @NotNull
        @Size(min = 5, max = 14, groups = OptionalChecks.class)
        private String licensePlate;

        // getter and setter
    }

and an interface definition for our custom validation group

| OptionalChecks.java
    public interface OptionalChecks {
    }

with the following Apache Camel route, only the @NotNull constraints on the attributes manufacturer and licensePlate will be validated (Apache Camel uses the default group `javax.validation.groups.Default`).

    from("direct:start")
    .to("bean-validator://x")
    .to("mock:end")

If you want to check the constraints from the group `OptionalChecks`, you have to define the route like this

    from("direct:start")
    .to("bean-validator://x?group=OptionalChecks")
    .to("mock:end")

If you want to check the constraints from both groups, you have to define a new interface first

| AllChecks.java
    @GroupSequence({Default.class, OptionalChecks.class})
    public interface AllChecks {
    }

and then your route definition should looks like this

    from("direct:start")
    .to("bean-validator://x?group=AllChecks")
    .to("mock:end")

And if you have to provide your own message interpolator, traversable resolver and constraint validator factory, you have to write a route like this

    <bean id="myMessageInterpolator" class="my.ConstraintValidatorFactory" />
    <bean id="myTraversableResolver" class="my.TraversableResolver" />
    <bean id="myConstraintValidatorFactory" class="my.ConstraintValidatorFactory" />

    from("direct:start")
    .to("bean-validator://x?group=AllChecks&messageInterpolator=#myMessageInterpolator&traversableResolver=#myTraversableResolver&constraintValidatorFactory=#myConstraintValidatorFactory")
    .to("mock:end")

It's also possible to describe your constraints as XML and not as Java annotations. In this case, you have to provide the file `META-INF/validation.xml` which could looks like this

| validation.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <validation-config
    	xmlns="http://jboss.org/xml/ns/javax/validation/configuration"
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/configuration">
    	<default-provider>org.hibernate.validator.HibernateValidator</default-provider>
    	<message-interpolator>org.hibernate.validator.engine.ResourceBundleMessageInterpolator</message-interpolator>
    	<traversable-resolver>org.hibernate.validator.engine.resolver.DefaultTraversableResolver</traversable-resolver>
    	<constraint-validator-factory>org.hibernate.validator.engine.ConstraintValidatorFactoryImpl</constraint-validator-factory>

    	<constraint-mapping>/constraints-car.xml</constraint-mapping>
    </validation-config>

and the `constraints-car.xml` file

| constraints-car.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <constraint-mappings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/mapping validation-mapping-1.0.xsd"
    	xmlns="http://jboss.org/xml/ns/javax/validation/mapping">
    	<default-package>org.apache.camel.component.bean.validator</default-package>

    	<bean class="CarWithoutAnnotations" ignore-annotations="true">
    		<field name="manufacturer">
    			<constraint annotation="javax.validation.constraints.NotNull" />
    		</field>

    		<field name="licensePlate">
    			<constraint annotation="javax.validation.constraints.NotNull" />

    			<constraint annotation="javax.validation.constraints.Size">
    				<groups>
    					<value>org.apache.camel.component.bean.validator.OptionalChecks</value>
    				</groups>
    				<element name="min">5</element>
    				<element name="max">14</element>
    			</constraint>
    		</field>
    	</bean>
    </constraint-mappings>