Adding a Field to Another Module's Form

To add a field for your own site, use the Form Designer: no module needed. See Using the Form Designer.

Use a module when the field belongs to your module's feature, and should appear only while your module is active. The Timeline module does this: its Add to Timeline checkbox appears on other modules' create forms.

Every form fires the form_display event before it's shown. Listen for it in _init():

jrCore_register_event_listener('jrCore', 'form_display', 'xxFoo_form_display_listener');

And add your field when the form is the one you want:

function xxFoo_form_display_listener($_data, $_user, $_conf, $_args, $event)
{
    if (isset($_data['form_view']) && $_data['form_view'] == 'jrProfile/settings') {
        $_tmp = array(
            'name'     => 'profile_color',
            'label'    => 'Profile Color',
            'help'     => 'A hex color code for the background of your profile',
            'type'     => 'text',
            'validate' => 'printable',
            'required' => false
        );
        jrCore_form_field_create($_tmp);
    }
    return $_data;
}

form_view is (module)/(view) of the form, such as jrProfile/settings or jrAudio/create. Check it, so the field only goes on that form.

The field is saved with the item, like the form's own fields. Use the form's prefix, such as profile_ on the profile settings form: a field without it isn't saved to that item. The value is then {$profile_color} in profile templates, and can be used in {jrCore_list} like any key.

To find a form's view name, write $_data to the Debug Log with fdebug($_data) and open the form. See Reading the Debug Log.