Warning because of empty value at array_flip()

+++ b/core/lib/Drupal/Core/Entity/FieldableDatabaseStorageController.php
@@ -181,15 +193,16 @@ public function loadMultiple(array $ids = NULL) {
+      If ($passed_ids) {

This If must be lowercase.

Helping Panchiniak with his first patch ;)

Rerolling against HEAD.

I cannot reproduce this bug on a fresh standard D8 install. Can you please provide more steps to reproduce?

I verify, that the notice appeared and that the Patch fixes this.

I found however, that a FATAL error appears, if you enter a default value and press Save, but this seems to be unrelated to this issue, as it also happens without applying the patch above.

Created a bug report for the issue mentioned above here: https://drupal.org/node/2195973

(Done during the Drupal South 2014 Code Sprint in Wellington)

I followed the traceback to TaxonomyAutocompleteWidget and fixed it there.
But I wonder if $items shouldn't just be empty (and skip the whole foreach loop).

I think a better fix would be to check if $items is not empty before trying to compute the default value for the form element, just like Entity reference does.

Tested, it works fine.

I've tested the #12 also and it's OK.

I was thinking about the solution we have right now and I'm not sure about this anymore.

Taking in count that the system has to have a tid in order to store the default value the best thing to do would be warn the user about the creation of the default term.

Earlier I was thinking to approach this with a checkbox to allow the user to decide if he/she wants to create the default value if it doesn't already exists but now I realized that maybe the best solution is to be verbose and let the user to know how the system works. I'm not sure if the creation of the default term outside of the "admin/structure/taxonomy/manage/[vocabulary]/add" page makes sense for everyone but thats the way the system works. So the end user has to be aware.

What do you guys think about this?

I've tested again trying to set 2 tags as the default value for the articles and I've got another error:

Fatal error: Call to a member function uuid() on a non-object in /[...]/core/modules/taxonomy/lib/Drupal/taxonomy/Plugin/Field/FieldType/TaxonomyTermReferenceFieldItemList.php on line 74

After that I clicked Back in the browser and I had the same error about the array_flip() plus a notice:

Warning: array_flip(): Can only flip STRING and INTEGER values! in Drupal\Core\Entity\FieldableDatabaseStorageController->loadMultiple() (line 147 of core/lib/Drupal/Core/Entity/FieldableDatabaseStorageController.php).

Notice: Undefined index: in Drupal\taxonomy\Plugin\Field\FieldType\TaxonomyTermReferenceFieldItemList->defaultValuesFormSubmit() (line 74 of core/modules/taxonomy/lib/Drupal/taxonomy/Plugin/Field/FieldType/TaxonomyTermReferenceFieldItemList.php).

I'm moving the status back to Needs work.

@revagomes there's another issue for that: #2195973: Setting default value on Article->Tags field leads to FATAL error..
This issue is RTBC already.

Looks like we could add test coverage for this. Patch itself looks fine though.

@catch can't the test come from #2195973: Setting default value on Article->Tags field leads to FATAL error.? This is just a trivial fix, the other issue is the heavy thing.

Added a test case to check if no PHP error is present on the field instance settings page for autocomplete widget.

Adding a missing newline.

This patch contains only the test (and not the fix) so it should fail.

22: core-taxonomy_autocomplete_warning-2193237-22.patch queued for re-testing.

22: core-taxonomy_autocomplete_warning-2193237-22.patch queued for re-testing.

I checked the page before applying the patch and after it.
Please see the screenshots.

Before:

After:

Patch #22 worked for me.

Committed a6658cd and pushed to 8.x. Thanks!