Deletion of menu items on the Navigation screen.

[talldan]

Is your feature request related to a problem? Please describe.
#21036 implemented the experimental nav screen. Currently menu items can be added or modified, but can't be removed.

Describe the solution you'd like
In addition to get and save functions, the core data package also exposes a remove/delete function for entities. This is used to allow the deletion of menu items in this code:

gutenberg/packages/edit-navigation/src/components/menu-editor/use-navigation-blocks.js

Line 93 in 37bda8a

// TODO - delete menu items.

[draganescu]

This is a bit complicated by the fact that the menu items which the useNavigationBlocks hook gets and serves up to it's calee's are not connected by any value to the menu items in the DB (ideally this should be by ID).

One reason for this is that in the navigation link block the concept of ID is completely different and refers to the id of the post linked to. In the context of menu items ID is the menu item's entry number in the wp_postmeta.

Since useNavigationBlocks artificially creates innerBlocks out of menu items we could:

1. reuse the id attribute of navigationLink in this context to mean something else
2. add a new attribute to navigationLink that is only used in this context

I try to use (1) since the two contexts are not likely to be interchangeable.

[draganescu]

Later edit

Apparently invalidateCache:true in the delete action caused the issue.

Problem description

Eventually, the problem we hit here is about the entities system not supporting `delete` operations on `Entity` data. We went ahead and tried different approaches to implement delete (with and without undo) but we have uncovered something which appears to be a bug in the Entities system, explained briefly like this:

There is something that calls receiveEntityRecords after the delete flow has completed. This causes that in effect:

1. The items get deleted from the DB by the apiFetch call
2. The items get removed from the state by the REMOVE_ITEMS action in the items reducer
3. The items appear back in the state by some mysterious call to receiveEntityRecords

Step 3 is done through some auto-magic wiring between apiFetch or getEntityRecords and the state. It is weird and unexpected.

[draganescu]

#22603 closed this.