[wp-trac] [WordPress Trac] #51612: `render_block_data` for nested blocks - WP_Block::render vs render_block

[WordPress Trac]

#51612: `render_block_data` for nested blocks - WP_Block::render vs render_block
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 Reporter:  gaambo                    |       Owner:  (none)
     Type:  defect (bug)              |      Status:  assigned
 Priority:  normal                    |   Milestone:  Future Release
Component:  Editor                    |     Version:  5.5
 Severity:  normal                    |  Resolution:
 Keywords:  has-unit-tests has-patch  |     Focuses:
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Comment (by gaambo):

 I've added a new PR on github to change the `WP_Block::render` method to
 use `render_block` for inner blocks as proposed by @azaozz. This fixes the
 bug in my test cases.
 It can be tested by creating a post/page with a group block and an inner
 block (eg paragraph) and adding the code from ticket:51612#comment:4
 somewhere (plugin, functions.php) and ensuring it outputs the data for the
 group and paragraph block.

 I've also written an unit test `test_calls_block_filters_for_inner_blocks`
 to prevent future regressions.

 The **problem is it breaks two other tests**:
 `Tests_Blocks_wpBlock::test_passes_content_to_render_callback` and
 `Tests_Blocks_wpBlock::test_render_static_block_type_returns_own_content`.
 I've debugged them and the problem is the following:
 In these tests a custom block registry instance is passed to the `WP_Block
 constructor`. The `WP_Block constructor` get's the `WP_Block_Type`
 instance from this registry and saves it in a property of the block
 instance. With the proposed changed it now creates a `WP_Block` instance
 for each inner block but calls `render_block` in `render`, which creates a
 new `WP_Block` instance for the parsed block again. Since `render_block`
 has no way of passing a block registry instance it passes none to
 (re-)creating the new block instance and then `WP_Block` just assumes the
 global block registry. Which lead's to `empty(
 $this->block_type->skip_inner_blocks )` (`class-wp-block.php:206`) not
 evaluating to true and therefore not calling the render code in this if.

 I'm not sure how to go about this. I tried changing all tests to use
 `render_block` instead of creating new `WP_Block` instances and rendering
 them. But that brings the same problem and I don't think it's a test-
 problem but rather an implementation problem.

 Another way could be to allow passing a block registry instance to
 render_block but I don't know if that's good? Seems we're back to talk
 about the use-cases of render_block and WP_Block::render 🤷‍♂️

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Ticket URL: <https://core.trac.wordpress.org/ticket/51612#comment:54>
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