VersionPress 4.0 support

[Ramoonus]

https://blog.versionpress.net/2017/07/versionpress-4-0-beta/

[borekb]

Cool to see this ticket! Some previous discussion:

• https://github.com/versionpress/versionpress/issues/1036#issuecomment-217214337
• https://github.com/versionpress/versionpress/issues/1036#issuecomment-217222843

[sc0ttkclark]

I think a good first goal is to ensure versioning the Pods configurations themselves works correctly. A main issue with versioning the configs themselves are dealing with table schema changes, field renaming (meta keys won't match, etc), field deletions (meta values will still be there, table columns/values will still be there).

[Ramoonus]

it will be tough, but a huge functionality improvement

[lougreenwood]

FYI - I'm already storing dumps of my entire WP dev installation in git and dumping changes into the dump in branches. So may be able to give some insight into handling Pods config changes via git...

[pavelevap]

I am using Pods for my projects, so I started to play with VersionPress support.

• Pods configuration simply works, post types and postmeta are supported by default, only entities have to be checked. I tested adding several fields and I did not notice any problem.
• I also added support for podsrel table and related entities to start tracking data and it seems that it also works, but I will test also renaming fields, etc (PR incoming).

• Shortcode support has to be added and also some advanced components will be challenging (especially custom table storage).

Some related questions:

• Relationships and postmeta are deleted and then added (not updated) by default?
• For relationship field with name test-relation-field there are 2 similar postmeta with ID values _pods_test-relation-field (serialized value) and test-relation-field (simple value). I am not sure about the second one (there is no prefix), is this postmeta important?
• I tried to rename some field and it seems to me that it can be renamed only once? Postmeta old_name is changed, but when I change it once again, there is no relation to previous name (and that is why mentioned postmeta test-relation-field will not work correctly)?

[lougreenwood]

Nice work @pavelevap! 👍