[META] Todo list for feature parity with D7

[docwilmot]

Please see the META Release blockers issue for the release-blocking issues.

Here is a longer todo list:

• what to do when rendering a referenced entity that references other entities?
• validate that the text matches the title of the entity with the entered id
• figure out proper way to set widget title so it isn't repeated with multiple values.
• make sure that a default value can be set in the field instance settings form
• update field validation to test that the referenced entity meets current restrictions
• autocomplete to get entity labels that start with the typed text before just containing
• additional field formatter to display rendered entity
• multilingual support for label autocomplete
• Use delivery callback to return json

Please see the META for tests to be added
Upgrade paths:

• Upgrade path from term_reference #60
• Upgrade path from D7 entityreference #28
• Upgrade path from references module (node_reference and user_reference) #59

Possible core changes:

• let title be configured in manage field display
• add plural for bundle labels
• hide the numeric id from the user after autocomplete select
• standardized autocomplete widget
• (replace references provided by other core modules, such as taxonomy tags and other term refs)
• add bundles for file entities
• file key for includes in hook_field_widget_info and hook_field_formatter_info
• file key for includes in hook_field_info

Needed core changes for File :

• url to handle file stream wrappers: Fixed: File::uri() is not consistent with other Entity types. backdrop/backdrop-issues#2300
• file entity uri returns options array: $enitity->uri() function for file entities does not return options array. backdrop/backdrop-issues#2299

[xmacinfo]

Is it also possible to include:

• Reverse field relationship (a field that would display all nodes parent automatically), without requiring a view?

[herbdool]

Can we add hooks to this list so that the behaviour and selection of the field can be extended by other modules? (Much like in entity reference, references).

[mikemccaffrey]

@herbdool We can add hooks where folks are finding that they need them. However, for the most part, it seems desirable for other modules to just define their own field formatters and selection widgets if they are looking for functionality that differs from the default behavior.

If anyone thinks that we should provide a hook in a particular location, can you please open a issue for just that?