Support for WordPress 5.0 and the new editor

[bobbingwide]

Since early 2017 a new Block editor has been under development. Code named Gutenberg this new editor is being developed as a feature plugin. It is expected to be merged into core for WordPress 5.0.

Over time, more content will be created using the Block editor than the Classic editor.
The new solution needs to be backward compatible with our existing solution, so there shouldn’t be a need to change anything and it should still work. But that has not yet proven to be the case.
Also, over time, more content will be created/edited using the Block editor than the Classic editor.
We need to embrace the improvements.

So, rather than being compatible with Gutenberg we need to be Gutenberg aware.

For oik-fields there are two areas.

1. Fields which rely on JavaScript to be displayed in meta boxes
2. Fields which will need to be accessible in the Block editor through the REST API.

Area	Problem	Reference
show_in_rest	oik-fields does not support show_in_rest
Google map virtual field	requires Google Maps JavaScript
Show_in_rest	Not all data can be exposed using the REST API	Security

Non functional requirements

• The solutions implemented for oik-types and oik-fields should be logically consistent.
• Where possible the code should use shared library logic
• New code should be tested
• Code should be internationalised and localized
• It should not cause Notices or Warnings, even when WP_DEBUG is true
• Backward compatibility with WordPress 4.9.x as a minimum
• Tested with PHP 7.1 and 7.2

[bobbingwide]

There's a third area. Fields which already produce unexpected messages when the content is displayed as part of the [bw_field] or [bw_fields] shortcode.

[bobbingwide]

There's a third area. Fields which already produce unexpected messages when the content is displayed as part of the [bw_field] or [bw_fields] shortcode.

Problems detected are
email field without a value produces

Warning: strlen() expects parameter 1 to be string, array given in C:\apache\htdocs\wordpress\wp-includes\formatting.php on line 2502

Notice: Array to string conversion in C:\apache\htdocs\wordpress\wp-content\plugins\oik\shortcodes\oik-email.php on line 92

Media field produces
Fatal error: Uncaught Error: Call to undefined function bw_thumbnail() in C:\apache\htdocs\wordpress\wp-content\plugins\oik-media\includes\oik-media.inc:62

[bobbingwide]

WordPress 5.0 was released on 6th December 2018. The latest version of oik-fields does co-exist peacefully with WordPress 5.0 and Gutenberg 4.8. There are some instances where updates to post meta fields, performed server side, are not reflected in the Block editor display. You need to reload the editor to see the changes.

[bobbingwide]

As part of the fix for bobbingwide/oik#120 I prototyped a change to the bw_metadata() function that supports the [bw_fields] shortcode. It calls oik_is_shortcode_expansion_necessary() to determine if oik thinks it's worth expanding shortcodes.

It's not caused any problems that I'm aware of so I'm happy to commit it... with oik-fields dependent upon oik v3.3.0