Interactivity API: Directives cannot access derived state properties on the server

[jonsurrell]

If a directives includes derived state in a non-final position, and this is implemented with server-side derived state, this causes an error and the directive is not processed correctly. For example:

<p data-wp-text="state.derivedState.property"></p>

Where the state might look something like this:

<?php
array(
  'derivedState' => function() {
    return array( 'property' => 'Hello, world!' );
  },
);

This will error and fail to process correctly on the server. On the client with derived state getters, this will work fine.

In some cases, derived state returns and object. Directives may wish to
continue to access properties of the object. Support this behavior.

On the client, derived state is implemented as JavaScript getters. This
transparently supports traversing a directive value like this:

state.derivedState.property

We can support this behavior on the server by handling derived state at
whatever the current value is for evaluation.

Trac ticket: https://core.trac.wordpress.org/ticket/61741

[luisherranz]

In 58825:

Interactivity API: Allow server derived state to appear in non-final position

In some cases, derived state returns an associative array. Directives may wish to continue to access properties of the associative array, when using the syntax state.arrayReturnedByClosure.property. This patch continues evaluating the path after the associative array has been returned by the Closure.

Props jonsurrell, luisherranz.

Fixes #61741.

Committed to Core in https://core.trac.wordpress.org/changeset/58825.

Thanks, Jon 🙂

[luisherranz]

Reopening for 6.6.2 consideration.

[adamsilverstein]

PR looks good to me @luisherranz - should the @since line read 6.6.2? +1 to backporting.

[jonsurrell]

Replying to adamsilverstein:

should the @since line read 6.6.2? +1 to backporting.

Support for derived state on the server was added in 6.6.0. I added @since 6.6.0 intentionally since it was omitted when the feature was introduced.

[gziolo]

It looks good to backport to WP 6.6.2.

[luisherranz]

In 58869:

Interactivity API: Allow server derived state to appear in non-final position

In some cases, derived state returns an associative array. Directives may wish to continue to access properties of the associative array, when using the syntax state.arrayReturnedByClosure.property. This patch continues evaluating the path after the associative array has been returned by the Closure.

Reviewed by adamsilverstein and gziolo.
Merges [58825] to the 6.6 branch.

Props jonsurrell, luisherranz, adamsilverstein, gziolo.

Fixes #61741.