Currently, deselecting all values from a multiple dropdown rendered as
checkboxes doesn't have any effect when submitting the form (the
previous values are still there, instead of being deselected).
This is because unchecked checkboxes are not sent by the browser – so
the "empty selection" never gets sent.
Rails `form.check_box` usually works around this by inserting an empty
hidden checkbox element, that will be sent even if all others are
de-selected. But the documentation warns that this is not possible when
iterating over an array (rather than a model). Which is our case here.
To fix this, this commit uses `collection_check_boxes` instead. It will
insert the proper hidden checkboxes in all cases, and fix our use case.
See https://api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html#method-i-collection_check_boxes
After clicking on a radio button option, it is impossible to revert to
the "None of the values selected" state.
However on non-mandatory fields, reverting to the no-selection value
should be possible.
To fix this, add an explicit "N/A" option.
- Make `type_de_champ.procedure` a requirement;
- Move the procedure_id assignation to `before_validation` (otherwise
the record is invalid, and never gets saved);
- Make `champ.dossier` a requirement;
- Move the dossier_id assignation to `before_validation` (otherwise
the record is invalid, and never gets saved);
- Allow specs to only build the champ (instead of saving it to the
database), which bypasses the requirement to have a dossier.
This makes `ActionDispatch::Controller#content_type` return not only
the MIME type, but also in some circumstances the charset.
Example:
```ruby
reponse.content_type == 'text/html; charset=utf-8'
```
The MIME type-only fragment can now be accessed using `#media_type`.
Changes to the tests are not stricly necessary (because no charset is
present in the actual value), but represent the intent better.
