forms: take the choice type into account when summing up the possibility of empty_data

[appeltaert]

http://symfony.com/doc/current/reference/forms/types/choice.html#overridden-options
"If data_class is set and required is false, then null;"

this doesn't work out for a choice field with the multiple attribute for example.

symfony/symfony#11349

[wouterj]

After investigating this issue, I see big problems with the empty_data documentation for all form types. To simplify maintenance, all types simply include a template for this specific setting. But it turns out that this setting is completely different for each form type.

For instance, the docs of the Text form type has the same content, while it doesn't have a data_class option at all.

In case of the choice type the default value is pretty simple: array() when multiple is true and an emty string ('') in all other cases.

These form type references currently use this template and should be changed:

• text
• textarea
• money
• radio
• email
• url
• password
• search
• form
• language
• country
• currency
• number
• integer
• timezone
• locale
• percent
• file
• choice
• entity
• collection

When doing this, I propose to reduce the template (options/empty_data.rst.inc) to:

empty_data
~~~~~~~~~~

**type**: ``mixed`` **default**: depends on other field options, see below

This option determines what value the field will return when the submitted
value is empty.

.. note::

    If you want to set the ``empty_data`` option for your entire form class,
    see the cookbook article :doc:`/cookbook/form/use_empty_data`.

And then add all custom information (including the exact default value) after the include directive.

[stof]

In case of the choice type the default value is pretty simple: array() when multiple is true and an emty string ('') in all other cases.

it is also an array for expanded types

For instance, the docs of the Text form type has the same content, while it doesn't have a data_class option at all.

technically, it has the option, as it inherits from the form type. But it is true that passing a data_class there does not make sense

[xabbuh]

#4083 has been merged.