Database schema for image field

Question

I have a module which behaves much like question and answers. Each question needs to have a help image. So far, I have written the schema as this:

function mymodule_schema() {
  $schema(mymodule_questions) = array(
      'description' => 'Stores questions for my module',
      'fields' => array(
          'qid' => array(
            'type' => 'serial',
              'not null' => TRUE,
              'description' => 'Primary Key: Question ID.'
          ),
          'prompt' => array(
             'type' => 'text',
              'not null' => TRUE,
              'size' => 'normal',
              'description' => 'Question prompt',
              'length' => '1000'
          ),
          'option_type' => array(
              'type' => 'varchar',
              'not null' => TRUE,
              'description' => 'Option Type',
              'length' => '255'
          ),
          /* Image field schema goes here */
      ),
  );
}
?>

Now, I want to add an image field, i.e. a field where admins can upload images to be shown with each question. What should be the schema for this field? Should I use the Field API in the schema (is that possible?)? If yes, how?

Thanks.

Kaustav Das Modak

Answer 1

To be able to integrate with field API, you would need to declare your custom data thing as a fieldable entity. This is possibly, but it is quite a bit of work and then you'll have to add the field in a install hook.

What you can do as well is simply add a single 'fid' integer column to your table, add a form element of #type 'managed_file' to your form, which will automatically save the file for you and create an entry in the file_managed table. You can then simply reference the fid (file id) of that object. Also note that you need to call file_usage_add() so that the managed file knows that it is in use. When your object is deleted, use file_usage_delete() then the file will automatically be removed.

This is exactly what is done in Drupal 7 for profile pictures, have a look at user_save() for an example.