[Spring framework Form Validation] disallowed field validation

Question

Hi there

I'm new with spring framework. I'm currently building some news manager form.

Here a sample of my news entity :

class News
{
    @NotNull
    long id;
    @NotNull
    long idAuthor;
    @Size(max=255)
    String content;
}

As you can see, I use JSR303 annotation validation with Spring. I want to validate my "news edit form".

@RequestMapping( value = "/edit" , method = RequestMethod.POST)
    public String editAction(@Valid @ModelAttribute News news, BindingResult result)
    {   
        System.err.println(result.hasErrors());
          ...
            return "editView";
    }

Define allowed field :

//initBinder function :
     binder.setAllowedFields("content");

Well, i'm trying to validate only "content" field (allowed field set on my binder)... But Spring always validate all the field defined on my entity (so "id" & "idAuthor" return error)

How can i only validate allowed field (set on initBinder function) ?

Answer 1

There are no good ways to do it.

JSR-303 offers two approaches for selective validation:

• You may validate specific properties by calling validator.validateProperty(news, "content")

• You may define validation groups:

  @Size(max=255, groups = {Default.class, WebValidation.class})      
  String content; 
  

  And validate the specified group: validator.validate(news, WebValidation.class);

None of these approaches are directly supported by Spring MVC. You can autowire a JSR-303 Validator and call these methods manually, but they return Set<ConstraintViolation<?>>, and the code for putting these ConstraintViolations into BindingResult is buried deep inside the Spring internals and can't be easily reused (see SpringValidatorAdapter).

There is a feature request for supporting validation groups in @Valid-style approach (SPR-6373) with fix version 3.1.

So, aside from creating a special DTO class, you doesn't have many options: you can use manual validation (without JSR-303), or you can copy-paste the code from SpringValidatorAdapter into your own utility method and manually call the methods of JSR-303 Validator.