Use Apache Solr Views for auto complete entity reference selection

Thanks for the info on Search API. However, my site is currently utilizing the Drupal ApacheSolr module heavily, and my understanding is that it is not advisable to utilize both the ApacheSolr module, and the Search API module at the same time.

Any idea on how entity reference autocomplete could be made to work with ApacheSolr and ApacheSolr Views?

(I'm going to move this thread to the ApacheSolr Views issue queue to see if anyone there can advise...

Looking into this a bit further, the main issue seems to be the fact that the entity reference views selection handler is not set up to work with a view that has a base table that is different from the base table of the entity that is beings searched.

Any view that is set up with ApacheSolr Views will have "apachesolr__solr" as the base table, which won't work with entity reference currently.

See EntityReference_SelectionHandler_Views.class.php:

if ($view->base_table == $entity_info['base table']) {
...
}

Any idea of how one could get this to work? Entity reference autocomplete would be a lot more powerful if one could utilize Solr as the backend...

Have gotten this partially working by:

1. Removing the check for $view->base_table == $entity_info['base table'] in EntityReference_SelectionHandler_Views.class.php.

2. Hardcoding $id_field_alias = 'entity_id' in entityreference_plugin_style.inc ($id_field_alias = $this->display->handler->id_field_alias does not work out of the box for the apachesolr powered view).

The autocomplete field now actually displays some results based on the apachesolr view, and if I select an item it is referenced correctly on save... but no search is actually taking place: I get the same 10 default results regardless of what text I type in the autocomplete field. See screenshot: http://i.imgur.com/wQUWEhY.png

So how can I set this up to actually search through the results using Apache Solr as the search backend?

Here's an export of the view that I'm using:

$view = new view();
$view->name = 'solr_test_view';
$view->description = '';
$view->tag = 'default';
$view->base_table = 'apachesolr__solr';
$view->human_name = 'Solr Test View';
$view->core = 7;
$view->api_version = '3.0';
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */

/* Display: Master */
$handler = $view->new_display('default', 'Master', 'default');
$handler->display->display_options['title'] = 'Solr Test View';
$handler->display->display_options['use_more_always'] = FALSE;
$handler->display->display_options['access']['type'] = 'none';
$handler->display->display_options['cache']['type'] = 'none';
$handler->display->display_options['query']['type'] = 'views_query';
$handler->display->display_options['exposed_form']['type'] = 'basic';
$handler->display->display_options['pager']['type'] = 'full';
$handler->display->display_options['pager']['options']['items_per_page'] = '10';
$handler->display->display_options['style_plugin'] = 'table';
$handler->display->display_options['style_options']['columns'] = array(
  '_version_' => '_version_',
);
$handler->display->display_options['style_options']['default'] = '-1';
$handler->display->display_options['style_options']['info'] = array(
  '_version_' => array(
    'sortable' => 0,
    'default_sort_order' => 'asc',
    'align' => '',
    'separator' => '',
    'empty_column' => 0,
  ),
);
/* Field: Apache Solr: label */
$handler->display->display_options['fields']['label']['id'] = 'label';
$handler->display->display_options['fields']['label']['table'] = 'apachesolr__solr';
$handler->display->display_options['fields']['label']['field'] = 'label';
$handler->display->display_options['fields']['label']['label'] = '';
$handler->display->display_options['fields']['label']['element_label_colon'] = FALSE;
/* Sort criterion: Apache Solr: label */
$handler->display->display_options['sorts']['label']['id'] = 'label';
$handler->display->display_options['sorts']['label']['table'] = 'apachesolr__solr';
$handler->display->display_options['sorts']['label']['field'] = 'label';
$handler->display->display_options['sorts']['label']['order'] = 'DESC';
/* Filter criterion: Apache Solr: bundle */
$handler->display->display_options['filters']['bundle']['id'] = 'bundle';
$handler->display->display_options['filters']['bundle']['table'] = 'apachesolr__solr';
$handler->display->display_options['filters']['bundle']['field'] = 'bundle';
$handler->display->display_options['filters']['bundle']['value'] = 'graphic';

/* Display: Entity Reference */
$handler = $view->new_display('entityreference', 'Entity Reference', 'entityreference_1');
$handler->display->display_options['defaults']['title'] = FALSE;
$handler->display->display_options['pager']['type'] = 'some';
$handler->display->display_options['defaults']['style_plugin'] = FALSE;
$handler->display->display_options['style_plugin'] = 'entityreference_style';
$handler->display->display_options['style_options']['grouping'] = array(
  0 => array(
    'field' => 'label',
    'rendered' => 0,
    'rendered_strip' => 0,
  ),
);
$handler->display->display_options['style_options']['search_fields'] = array(
  'label' => 'label',
);
$handler->display->display_options['defaults']['style_options'] = FALSE;
$handler->display->display_options['defaults']['row_plugin'] = FALSE;
$handler->display->display_options['row_plugin'] = 'entityreference_fields';
$handler->display->display_options['row_options']['separator'] = '';
$handler->display->display_options['defaults']['row_options'] = FALSE;

It occurs to me that since I want apache solr to be used as the actual backend of the autocomplete searching, the best approach to solving this issue may be to simply integrate with the Apache Solr Autocomplete module, and provide a mode for that under "entity selection mode" in the entity reference widget settings. See screenshot: http://i.imgur.com/ckr7h6P.png

Thoughts?