Module adds cache tags for every entity of the bundle being paged

Thanks for reporting this.

> Really, it should only invalidate the immediately preceding and immediately following entities, if that is all that is configured to show.

That's not the right fix, unfortunately. If only it were that simple!

Suppose I made a pager view which orders nodes by their 'floopiness' integer field, and I have nodes with these values:

A: 1
B: 2
C: 10

Node B is between A and C, so you might only think it needs to have cache tags for A and C. But now I create node D with a value of 3! The pager shown on nodes B and C needs to be invalidated.

The only way to do this is to add the node_list (generically, the list cache tag).

In fact, that's a second bug: currently with the single node cache tags, B and C's pagers won't be invalidated.

(If we had #3279764: Segmented ENTITY_TYPE_list:* cache tags, we could have a setting where you can be more specific.)

Although -- I am not seeing where these cache tags are being added in the module's code. Are you sure it's coming from Entity Pager and not from Views?

Hi both,

I ran into this exact issue ("Premature end of script headers" / HTTP status 500) on a site with ~538 news nodes and I guess the source is views core, just triggered by entity_pager's usage pattern:

in views, StylePluginBase::renderFields() loops over every result row and calls $renderer->render($data) for each one. Inside that render, EntityFieldRenderer::render() does:

$build[$row_id]['#access'] = $entity->access('view', NULL, TRUE);

The TRUE argument returns a cacheable AccessResult object rather than a plain boolean. NodeAccessControlHandler returns an AccessResultAllowed carrying node:NNN as a cache tag. Drupal's Renderer::doRender() then automatically bubbles that AccessResult's cacheability into the active BubbleableMetadata context, independently of anything #cache['tags'] controls.

This fires once per row, producing one node:X tag per entity in the result set, all accumulated in the render context before the view output is assembled.

I think I could fix that with two things (at least in my case):

1) A custom views cache plugin overriding getRowCacheTags() to return ['node_list'] instead of $row->_entity->getCacheTags(). node_list is then invalidated on any node create, update, or delete

public function getRowCacheTags(ResultRow $row) {
  return ['node_list'];
}

2) Fields in the entity_pager view must be removed entirely. Even with the custom cache plugin correctly returning ['node_list'] from getRowCacheTags(), as long as any fields exist in the view, renderFields() still runs, still calls $renderer->render() per row, and EntityFieldRenderer still sets #access as a cacheable AccessResult, bubbling node:X tags right back in through BubbleableMetadata, bypassing the cache plugin.

perhaps entity_pager could ship its own views cache plugin (implementing the node_list approach above) and either document that fields should not be added to entity_pager displays, or override renderFields() in the style plugin to skip field rendering entirely when the display uses entity_pager, since that output is never displayed anyway?

> in views, StylePluginBase::renderFields() loops over every result row and calls $renderer->render($data) for each one

Thanks for figuring it out! That's very helpful.

> Fields in the entity_pager view must be removed entirely

I have considered this: see #3594033: set style to not allow fields