how do I troubleshoot an external database access?

Question

I successfully setup a Drupal 6 site to access external databases and present them in tables via Views.

Now I am trying to move to Drupal 7, and I'm not sure how to troubleshoot. In Drupal6, I can open table wizard after editing the settings.php file; it shows the new tables and I can add them.
Is there a way to know if Drupal 7 can see the database? I edited the settings.php file and created a module that is supposed to describe the database to Drupal 7, but I don't see the tables anywhere.

Any suggestions on how to troubleshoot? I don't get any errors or feedback; it simply doesn't do what I want it to do.

This is my code. I have a file called datamodel.module:

function datamodel_views_api() {
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'datamodel'),
  );
}

I have also a file called datamodel.views.inc. This file is very long but I basically got everything working in drupal6 using table wizards; then I used the table wizards to Views definition for hook_views_data(), which I put in the following code.

function datamodel_views_data() {
  $data = array();
  $data['FundManager'] = array(
    'FundManager' => array(
      'title' => t('FundManager'),
      'help' => t('FundManager.FundManager'),
      'field' => array(
        'handler' => 'views_handler_field',
        'click sortable' => TRUE,
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_string',
        'allow empty' => TRUE,
      ),
      'argument' => array(
        'handler' => 'views_handler_argument_string',
      ),
      'sort' => array(
         'handler' => 'views_handler_sort',
      ),
    ),
    'fundManagerCode' => array(
      'title' => t('fundManagerCode'),
      'help' => t('FundManager.fundManagerCode'),
      'field' => array(
        'handler' => 'views_handler_field_numeric',
        'click sortable' => TRUE,
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_numeric',
        'allow empty' => TRUE,
      ),
      'argument' => array(
        'handler' => 'views_handler_argument_numeric',
      ),
      'sort' => array(
        'handler' => 'views_handler_sort',
      ),
    ),
    'FundManagerFirm' => array(
      'title' => t('FundManagerFirm'),
      'help' => t('FundManager.FundManagerFirm'),
      'field' => array(
        'handler' => 'views_handler_field',
        'click sortable' => TRUE,
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_string',
        'allow empty' => TRUE,
      ),
      'argument' => array(
        'handler' => 'views_handler_argument_string',
      ),
      'sort' => array(
        'handler' => 'views_handler_sort',
      ),
    ),
    'FundManagerStartDate' => array(
      'title' => t('FundManagerStartDate'),
      'help' => t('FundManager.FundManagerStartDate'),
      'field' => array(
        'handler' => 'views_handler_field',
        'click sortable' => TRUE,
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_string',
        'allow empty' => TRUE,
      ),
      'argument' => array(
        'handler' => 'views_handler_argument_string',
      ),
      'sort' => array(
        'handler' => 'views_handler_sort',
      ),
    ),
    'FundManagerDescription' => array(
      'title' => t('FundManagerDescription'),
      'help' => t('FundManager.FundManagerDescription'),
      'field' => array(
        'handler' => 'views_handler_field',
        'click sortable' => TRUE,
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_string',
        'allow empty' => TRUE,
       ),
       'argument' => array(
         'handler' => 'views_handler_argument_string',
       ),
       'sort' => array(
         'handler' => 'views_handler_sort',
       ),
    ),
    'FundCode' => array(
      'title' => t('FundCode'),
      'help' => t('FundManager.FundCode'),
      'field' => array(
        'handler' => 'views_handler_field_numeric',
        'click sortable' => TRUE,
      ),
      'filter' => array(
        'handler' => 'views_handler_filter_numeric',
        'allow empty' => TRUE,
      ),
      'argument' => array(
        'handler' => 'views_handler_argument_numeric',
      ),
      'sort' => array(
        'handler' => 'views_handler_sort',
      ),
    ),
    'table' => array(
      'group' => t('FundManager'),
    ),
  );

  return $data;
}

I thought I followed the instructions, but nothing happens after I enable the module.

Answer 1

There are a few things you can do to debug this.

First up try switching the database and doing a general query on your 'fundmanager' table

Something like

 db_set_active('myexternal');
 $result = db_query('SELECT FundCode FROM fundmanager');
 db_set_active('default');

This will test that the database connection is working and visible from drupal.

If that is ok you can put some debug code in your hook_views_data() to make sure that is being called. Clear the cache and go to the list views page.

If both of these are present then it is likely a bug in your tablewizard code. This is a little buggy with external databases. It should define base_database somewhere but there is a bug

Answer 2

Most of the time, when something goes wrong there is an error displayed or logged somewhere depending on your PHP and system setup. Most Linux distributions provide a production safe PHP distribution that disable errors display. For developement, I suggest you enable errors display for PHP and install xdebug to enable stack traces in error messages.

In some rare occasions, Drupal fails to report an error and silently ignore the error. For these cases, tracing execution using Xdebug or the Zend Debugger are the best options. But they may take time to setup.