To validate entities in Elastic Path:

1. Get the validator instance
2. Pass the object to the validator through the validate(object) method

For example, this is how you validate a customer:

Validator validator = beanFactory.getBean("validator");
Set<ConstraintViolation<Customer>> violations = validator.validate(customer);

The validate(object) method returns a set of constraint violations. If this set is empty, the object passes validation. Otherwise, you can pass the constraint violations set to loggers or UI widgets to display validation errors.

Constraints specify the criteria the validation framework uses to determine if an object is valid. In Bean Validation, constraints are primarily provided in the form of annotations.

In Elastic Path, annotations are placed directly above an object's interfaces, classes, fields, and getter methods as shown:

@RegisteredCustomerPasswordNotBlankWithSize(min = Customer.MINIMUM_PASSWORD_LENGTH, max = GlobalConstants.SHORT_TEXT_MAX_LENGTH)
public interface Customer extends Entity, UserDetails, DatabaseLastModifiedDate {

...


	/**
	 * Get the username.
	 *
	 * @return the username
	 */
	@Override
	@NotNull
	@NotBlank
	@Size(max = GlobalConstants.SHORT_TEXT_MAX_LENGTH)
	@CustomerUsernameCheck
	String getUsername();