Select or exclude Views blocks that can be referenced

[olafgrabienski]

In the field settings of a Block reference field, there is the option to select "Modules defining blocks that can be referenced" (Block, Comment, Field, Menu, some more, and Views). When selecting Views, I'd like to limit the Views blocks that can be referenced by an editor. Is this already possible somehow, and/or can this option be added to the field settings?

[yorkshire-pudding]

I'm fairly sure it can't be done at the moment so would be an enhancement. I can see it being very useful and could make the experience much friendlier for editors if they have a shorter list.

[argiepiano]

Use hook_form_FORM_ID_alter()?

[olafgrabienski]

Use hook_form_FORM_ID_alter()?

@argiepiano Would that be an approach to add the feature, or a workaround?

[argiepiano]

Sorry, that's a workaround for you. Implement hook_form_FORM_ID_alter() in a small custom module to remove from that form, the Views blocks that are not allowed.

[yorkshire-pudding]

@olafgrabienski @argiepiano
Actually, there is an easier way. In

blockreference/blockreference.api.php

Lines 7 to 36 in 41d0405

	/**
	* Alter referenceable blocks, BEFORE the autocomplete match.
	*
	* These are always block objects, not options. You can change the option label
	* by changing $block->info.
	*
	* For autocomplete fields, this alter happens AFTER the search, before slicing
	* the results (ACDB does that).
	*
	* $context contains:
	* - instance
	* - type ("autocomplete" or "options_list", depending on where this list is
	* requested)
	* - entity
	* - entity_type
	*/
	function hook_blockreference_blocks_pre_alter(&$blocks, $context) {
	// These are all the blocks that match the field instance's referenceable
	// module option. If you were to change a block's label now, that's the
	// label the autocomplete will try to match.
	foreach ($blocks as $id => $block) {
	// Add module & delta to pretty label.
	$block->info .= ' (' . $block->module . '/' . $block->delta . ')';
	// Remove all Views blocks, except 'public_stuff'.
	if ($block->module == 'views' && strpos($block->delta, 'public_stuff-') !== 0) {
	unset($blocks[$id]);
	}
	}
	}

There is documentation for hook_blockreference_blocks_pre_alter()

It is quite easy to remove blocks using this. I'll post an example shortly

[yorkshire-pudding]

Example simple custom module:

my_custom_block_ref_limit.info

name = Block Reference Limit Entries
description = Limit the blocks available to certain Block Reference fields
type = module
backdrop = 1.x

dependencies[] = blockreference

package = Custom Modules
tags[] = Blocks
tags[] = Fields

my_custom_block_ref_limit.module

<?php
/**
 * @file
 *
 * Hooks and helpers for module.
 */

/**
 * Implements hook_blockreference_blocks_pre_alter().
 */
function my_custom_block_ref_limit_blockreference_blocks_pre_alter(&$blocks, $context) {

  $block_limits = array(
    'field_view_news_block' => array(
      'blocks' => array('views:news_display-block_news_relevant'),
    ),
    'field_metric_display_block' => array(
      'blocks' => array(
        'views:metric-block_metric_icon_display_location',
        'views:metric-block_metric_display_location',
      ),
    ),
  );
  $field_name = $context['instance']['field_name'];
  if (isset($block_limits[$field_name])) {
    $block_list = $block_limits[$field_name]['blocks'];
    foreach ($blocks as $module_delta => $block) {
      if (array_search($module_delta, $block_list) === FALSE) {
        unset($blocks[$module_delta]);
      }
    }
  }
}

[olafgrabienski]

Thanks for the example, @yorkshire-pudding, much appreciated! To be honest, I'm not sure how to adapt the example to my case. How would you change the following example to connect a field called field_page_blockreference with the default "Promoted cards" view (admin/structure/views/view/promoted_cards/configure/block)?

'field_view_news_block' => array(
      'blocks' => array('views:news_display-block_news_relevant'),
    ),

[yorkshire-pudding]

Thanks for the example, @yorkshire-pudding, much appreciated! To be honest, I'm not sure how to adapt the example to my case. How would you change the following example to connect a field called field_page_blockreference with the default "Promoted cards" view (admin/structure/views/view/promoted_cards/configure/block)?

'field_view_news_block' => array(
      'blocks' => array('views:news_display-block_news_relevant'),
    ),

@olafgrabienski - in this scenario it would be:

/**
 * Implements hook_blockreference_blocks_pre_alter().
 */
function my_custom_block_ref_limit_blockreference_blocks_pre_alter(&$blocks, $context) {

  $block_limits = array(
    'field_page_blockreference' => array(
      'blocks' => array('views:promoted_cards-block'),
    ),
  );
  $field_name = $context['instance']['field_name'];
  if (isset($block_limits[$field_name])) {
    $block_list = $block_limits[$field_name]['blocks'];
    foreach ($blocks as $module_delta => $block) {
      if (array_search($module_delta, $block_list) === FALSE) {
        unset($blocks[$module_delta]);
      }
    }
  }
}

What I did to work out the block delta was (with Devel enabled), add the following snippet to the top of the function.

  $data = array(
    '$blocks' => $blocks,
    '$context' => $context,
  );
  dpm($data);

Look in $blocks and you see each block as a key with a block stdClass. The key is what you want. It is basically the module (views) with the block delta separated by a colon :

The block delta is made up view_machine_name-block_machine_name, hence promoted_cards-block

[olafgrabienski]

The block delta is made up [view machine name]-[block machine name], hence promoted_cards-block

Ah, very helpful!
So in the case of Views blocks the necessary information is visible in the path of the block configuration page:
admin/structure/views/view/promoted_cards/configure/block

I've tested this with an array of three Views blocks -- works like a charm!