Views Reference Filter

This module provides the views filter for entity ID or entity reference fields:

• node ID
• user ID
• taxonomy term ID
• the ID of any other content entity
• entity reference field (Drupal core), including taxonomy term, node and user references
• fields indexed in Search API

Exposed filter functionality

Taxonomy term filtering:
Imagine the following case - you have taxonomy terms in exposed filter widget (drop down select list). But for some reason you want to show just several terms, not all the dictionary. With this module, you can do this by creating a separate view which generates the desired list of terms.

The similar functionality is available for other type of fields - you create a separate view (or a new display of the same view) which returns the list of items to show in drop down select list of the exposed filter.

Unexposed filter functionality

This module provides the feature missing in Views module - subquery filter for IN (NOT IN) condition, such as (quite informal):
SELECT n.title FROM node n WHERE n.nid [IN | NOT IN] (SELECT n2.nid FROM node n2 WHERE ...)
or
SELECT n.title FROM node n WHERE n.node_reference_field [IN | NOT IN] (SELECT n2.nid FROM node n2 WHERE ...)
The view with the filter generates the outer query, and the separate view generates the inner query. Current implementation is simplified - it gets the result of the subquery and puts the concrete values in the outer query.

The limitations of the view and the display providing the items for the filter

• the view display must be 'Entity Reference' type (provided by Drupal core Views)
• the base entity of the view (which you select in the beginning of view creation) must be the same as the type of the field being filtered (node for nid field, user for uid field, etc.)

By default, the view receives the same arguments as the view being filtered. This can be changed in the filter settings.
Possible value for any argument:

• the argument of the view being filtered
• any string value
• the value of any exposed filter of the view being filtered

The last option makes the exposed filter dependent on the other filter. This creates the functionality missing in the Views: dynamic dependent filters, i.e. when the value of the main filter is changed, the list of
options of the dependent filter is updated via AJAX. Filters can be chained into multi-level dependencies, and the cascade is resolved in order with cycle detection.