Symfony2 Validating an optional field

Question

In my form, I have a field with required option set to false, this field is optional.

However, I would like to have a notBlank validation on this field when the field is used:

@Assert\NotBlank(
 *     message="The name field can't be blank",
 *     groups={"flow_poemDataCollector_step1"}
 * )

Right now, I can't use the validation constraint NotBlank because it will cause my form validation to fail when the field is unused.

I tried something to add a random value in the field in a onPostBindRequest listener, but it is complex and didn't manage to have it working. I'm not sure that it is the right way to proceed neither.

Here is what I tried: ($form is a Symfony\\Component\\Form\\FormInterface object)

    $form = $event->getForm();
    $formData = $form->getData();
    $formData->setUserName("foo");
    $form = $form->setData($formData);

But then I get an error that I can't call isValid() on an unbound form.

How can I achieve my goal? ie. Validating the field only in some case.

Answer 1

This is an old question, but it seems that now we can do it this way:

@Assert\Optional(
    @Assert\NotBlank(
        message="The name field can't be blank",
        groups={"flow_poemDataCollector_step1"}
    )
)

ref: http://symfony.com/doc/2.7/reference/constraints/Collection.html

Answer 2

The best way I can see to achieve this is to use a Callback validator on your entity. As this callback is defined in your entity, it has access to all properties. Through the ExecutionContext you can then set violations as needed.

Answer 3

Hmm. I had to reread your question several times because something in it is not logically valid.

If you want the field to be not required then using the NotBlank constraint makes no sense. How can a field be not required and required at the same time?

If all you want is that if something is entered in that field doesn't consist of just spaces, then you don't need the NotBlank constraint at all because Symfony trims the user input by default, so it will end up as if nothing has been entered at all.

Answer 4

If you want the field to be optional, you can:

new Assert\\Length(array('min' => 0))

because omitting the field from the constraint will cause an Unexpected field error.

Answer 5

ended up here searching for how to make a field both optional and, if entered, validated, like an optional email:

from symfony docs:

As with most of the other constraints, null and empty strings are considered valid values. This is to allow them to be optional values. If the value is mandatory, a common solution is to combine this constraint with NotBlank.

https://symfony.com/doc/current/reference/constraints/Email.html

so the solution is just to validate as Email and the field will still be optional.