Drupal 7 Module Development

Working with Content
}
'#submit' => array('artwork_form_delete_submit'),
);
$form['#validate'][] = 'artwork_form_validate';
field_attach_form('artwork', $artwork, $form, $form_state);
}
return $form;
Once again, a fair number of lines but all fairly simple. First we set a fake property
on the form so that form_alter implementations may detect all artwork forms of
any type and stick the artwork object itself into the form in case we need it later in
validate or submit routines. We then add a form field for the title and a checkbox
to indicate whether we should save a new revision or overwrite the existing revision.
We then add not one but two buttons, one that is always available for the save
operation and another for deleting an artwork if we're editing an existing artwork.
More on that later.
The last line is very important. The field_attach_form() call is what passes our
form off to the Field system so that any fields we've added to this artwork type can
be added to the form. Think of it as a Field-specific form_alter operation. The form
properties that the Field system adds are quite complex, but we don't have to worry
about them. They just work.
Validation callback
Similar to the form, the validation callback passes most of its logic off to the
Field system.
function artwork_form_validate($form, &$form_state) {
$artwork = $form_state['artwork'];
}
// Field validation.
field_attach_form_validate('artwork', $artwork, $form, $form_state);
If we had any validation of our own we would include it here, but in this case any
validation we'd do (checking for required fields) the Form API already does for us.
All we need do is tell the Field system to do its own validation.
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