Hibernate Tips: How to validate that an entity attribute value is within a defined range

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Hibernate Tips is a series of posts in which I describe a quick and easy solution for common Hibernate questions. If you have a question you like me to answer, please leave a comment below.

Question:

The value of one of the attributes of my entity has to be within a defined range. What is the best approach to automatically validate the attribute value before persisting it?

Solution:

The Bean Validation Specification and its reference implementation Hibernate Validator provide easy to use and powerful validation options. It integrates with JPA and Hibernate ORM so that it triggers the validation for all entity attributes before persisting or updating an entity.

It only takes 2 steps to automatically validate that the value of an entity attribute is within a defined range. You need to:

• add the required dependencies to your project
• annotate the attribute with the BeanValiation annotations

You need to add the following maven dependencies to your project.

<dependency>
	<groupId>org.hibernate</groupId>
	<artifactId>hibernate-validator</artifactId>
	<version>5.4.1.Final</version>
</dependency>
<dependency>
	<groupId>javax.el</groupId>
	<artifactId>javax.el-api</artifactId>
	<version>2.2.4</version>
</dependency>
<dependency>
	<groupId>org.glassfish.web</groupId>
	<artifactId>javax.el</artifactId>
	<version>2.2.4</version>
</dependency>

In the next step, you need to define the validation. In this example, you need to annotate the entity attribute with @Min and @Max to define the lower and upper boundary of the valid range.

You can see an example of it in the following code snippet. It checks that the numPages attribute has a value between 100 and 1000.

@Entity
public class Book {

	@Min(100)
	@Max(1000)
	private int numPages;

	…
}

When you now try to persist a Book entity and the value of numPages is outside of the allowed range, Hibernate Validator throws one of the following exceptions.

14:54:05,684 ERROR [org.hibernate.internal.ExceptionMapperStandardImpl] - HHH000346: Error during managed flush [Validation failed for classes [org.thoughts.on.java.model.Book] during persist time for groups [javax.validation.groups.Default, ]
List of constraint violations:[
	ConstraintViolationImpl{interpolatedMessage='must be greater than or equal to 100', propertyPath=numPages, rootBeanClass=class org.thoughts.on.java.model.Book, messageTemplate='{javax.validation.constraints.Min.message}'}
]]

14:57:24,905 ERROR [org.hibernate.internal.ExceptionMapperStandardImpl] - HHH000346: Error during managed flush [Validation failed for classes [org.thoughts.on.java.model.Book] during persist time for groups [javax.validation.groups.Default, ]
List of constraint violations:[
	ConstraintViolationImpl{interpolatedMessage='must be less than or equal to 1000', propertyPath=numPages, rootBeanClass=class org.thoughts.on.java.model.Book, messageTemplate='{javax.validation.constraints.Max.message}'}
]]

Learn More

You can do a lot more than just the simple validation I showed in this Hibernate Tips. I explain the BeanValidation integration in more detail in How to automatically validate entities with Hibernate Validator.