PageTableArray::isValidItem() throws fatal WireException on page load in my setup

[er314]

After upgrading PW 3.0.253 -> 3.0.269, now I have runtime exceptions in the admin upon displaying pages containing PageTable field, with the error message "Item added to ProcessWire\PageTableArray is not an allowed type".
The root cause is PageTableArray::isValidItem(), which apparently does more checks now than before.
Here is the 2 cases which are now allowed-or-denied by PageTableArray::isValidItem() :

-1- If the PageTable field is configured with a given parent page for items (therefore "All items created and managed from this field will live under the parent you select here"), then PageTableArray::isValidItem() checks that the PageTable items are a direct child of this parent page, as expected (if not -> exception)

		if($field->parent_id) { 
			// specific parent required
			if($item->parent_id != $field->parent_id) return false;
		}

-> OK, good

-2- Otherwise, PageTableArray::isValidItem() checks that the PageTable items are a direct child of the page having the PageTable field (if not -> exception)

		} else {
			// forPage required as parent
			if($item->parent_id != $this->forPage->id) return false;
		}

-> I have a problem with this new enforcement,
because I'm using a 3rd use case :

-3- My PageTable field is NOT configured with a given parent page for items, AND I manually manage the location of the PageTable items.
This used to be accepted by PW, and this used to work perfectly fine.
Now, apparently it's no more accepted.
What I do precisely is :

• My PageTable field is configured with :
  . no contraint on the parent page for this field
  . template "order-item" is enforced for the items
• My page tree related to this PageTable field is :

	. Page with template "order"  -> this template has the PageTable field
		. Page with template "order-items-container"  -> this is where I place the PageTable items ; actually I create each of the item Pages via API, and I place them at this location via API
			. 1-to-N Page(s) with template "order-item" -> these are the PageTable items

For my use case, this setup is better than -1- and -2-, because the PageTable items which are bound to a given main page remain "nearby & below" their main page, while also being cleanly stored in a "subfolder" dedicated to them.

Note : as soon as I remove the new check -2-, all goes well as before, end to end.

As a conclusion, I propose that check -2- is removed, in order to allow use case -3- again (thereby fixing the regression).
By doing so, Processwire will stick to checking the validity of the settings which are configured for the Pagetable field ; no more, no less.

[ryancramerdesign]

Fixed in the dev branch. When no parent page is configured for the field, isValidItem() was requiring items to be direct children of the page owning the field — but that constraint was never something the admin configured, so it shouldn't be enforced. The check now only validates the parent when parent_id is explicitly set on the field; otherwise only the template check applies (if a template is configured). This restores the behavior that existed before PageTableArray was introduced and allows your container-page setup to work as before.

-Claude