Field Types and Settings

There are a defined number of field types in use, and each type has its own available settings (links below are to API HOOK_field_info() implementations).  The settings array can appear in three places: the field definition, in instance definition, or within the instance definition's widget array.

List of field types:

• file (File)
• image (Image)
• taxonomy_term_reference (Term Reference)
• List fields
  • list_boolean (Boolean)
  • list_float (List (Float))
  • list_integer (List (Integer))
  • list_text (List (Text))
  • Field settings
    • allowed_values (list_integer, list_float, list_text only.)
    • allowed_values[on] and allowed_values[off] (list_boolean)
  • Widget
    • settings[display_label] (options_onoff i.e. checkbox only)
• Number fields
  • number_decimal (Decimal)
  • number_float (Float)
  • number_integer (Integer)
  • field settings
    • precision (number_decimal only)
    • scale (number_decimal only)
    • decimal_separator (number_decimal and number_float only)
• Text fields
  • text (Text)
  • text_long (Long Text)
  • text_with_summary (Long Text with Summary)
  • Field settings
    • max_length. For unlimited textareas, set to ''
  • Instance settings
    • text_processing (enables text filters)
  • Widget
    • settings[size] (textfield only)
    • settings[summary_rows] (textarea_with_summary only)
    • settings[rows] (textarea)
• All fields
  • label
  • required
  • description (known as help text in the ui)
  • default_value[][value]
  • settings[description] ('help' text)

To discover settings, search the Drupal API for implementations of hook_field_settings_form. To discover widget options, search for implementations of hook_field_widget_form. This is very difficult to document because the code is distributed through a handful of modules, each with multiple relevant hooks to examine.