Fields::namesToIds index never invalidated after save/delete/rename — fieldNameExists() lies in same request

[adrianbj]

Short description of the issue

The new namesToIds index and the methods that consume it (fieldNameExists(), getAllNames(), getAllIds(), getFieldId($name)) were added across commits d367e636, f029159e, 13a42239, 7e80f3a5, 789b5a05. The index is populated only once, in Fields::loadAllItems() — ___save(), ___delete(), and the rename branch never update it. Within the same request, those API methods return stale data for any field that was just created/renamed/deleted.

Expected behavior

Immediately after $fields->save($newField) in the same request:

• $fields->fieldNameExists($newField->name) returns true.
• $fields->getAllNames() and $fields->getAllIds() include the new field.
• $fields->getFieldId($newField->name) returns the new ID.

Actual behavior

In wire/core/Fields/Fields.php:

• namesToIds is populated only in loadAllItems() (line ~215).
• ___save() does not update it.
• ___delete() does not update it.
• The rename branch ($item->prevName != $item->name, ~line 491) does not update it.
• getFieldId($name) was changed from looking up via $this->get($field) to a direct lookup against namesToIds (line ~1711), so it now returns 0 for fields that were just created.

Optional: Suggestion for a possible fix

In ___save():

if($isNew) {
    $this->namesToIds[$item->name] = $item->id;
} else if($item->prevName && $item->prevName !== $item->name) {
    unset($this->namesToIds[$item->prevName]);
    $this->namesToIds[$item->name] = $item->id;
}

In ___delete():

unset($this->namesToIds[$item->name]);

Steps to reproduce the issue

$f = $fields->new('text', 'my_test_field');
$fields->save($f);
var_dump($fields->fieldNameExists('my_test_field')); // expected true, actual false
var_dump($fields->getFieldId('my_test_field')); // expected nonzero, actual 0

Setup/Environment

• ProcessWire version: dev @ 15c749ed
• File: wire/core/Fields/Fields.php
• Introduced across commits d367e636, f029159e, 13a42239, 7e80f3a5, 789b5a05