[hibernate-issues] [Hibernate-JIRA] Created: (HV-462) Allow ordered validator's annotations

[Pavla Nováková (JIRA)]

Allow ordered validator's annotations
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                 Key: HV-462
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HV-462
             Project: Hibernate Validator
          Issue Type: New Feature
    Affects Versions: 4.1.0.Final
            Reporter: Pavla Nováková


1) Consider domain object with simple constraints (just to demonstrate required feature, my real example uses custom cost-expensive validation of pictures):

{code}
public class DomainObject {

	@Size(max=50) // constraint 1a
	@Pattern(regexp="[a-z]*") // constraint 1b
	private String name;
	
	@Size(max=20) // constraint 2a
	@URL // constraint 2b
	private String email;
	
	@Size(max=100) // constraint 3a
	@Pattern(regexp="[0-9]*") // constraint 3b
	private String password;
	
{code}

2) Consider validation requirements:

* all properties should be validated together (like one virtual group)
* FOR EACH PROPERTY validation should occur in ordered steps given by order of annotations for given property (if first validation step fails, SKIP following validation process on given property and add validation message specific to failed / last validated constraint for the property)

3) Why it is useful:

* simple cost-effective validation followed by cost-expensive validation (not executed if simple constraint fails)
* we get just the "main and specific validation error" (otherwise we have to iterate over all errors "to find the cause" or we display two or more errors for one property which is not user-friendly according my opinion)

3) What is unusable:

* groups and group sequences (it is not possible to create proper combination of groups and sequences for more than one property with two or more constraints)
* composed constraints (@ReportAsSingleViolation included)
** we cannot use @ReportAsSingleViolation since we want specific message for each failed constraint
** and main problem is: if we use composed constraints all constraints are evaluated for given property 

4) Proposed solution:

* add optional order attribute to validator annotations and stop validation on first failure if order is specified
* possibly this can be configured on global validator level with property "skipOnFirstFailure" together with some given convention for annotation order


Please let me know if need better explanation or working examples.

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