Array flip error when a taxonomy term field has a NULL value

I get the same error. I found that some taxonomy term fields have a NULL value in the database for my "tags" field. For example:

mysql> SELECT * FROM  field_data_field_tags WHERE field_tags_tid IS NULL;
+-------------+--------+---------+-----------+-------------+----------+-------+----------------+
| entity_type | bundle | deleted | entity_id | revision_id | language | delta | field_tags_tid |
+-------------+--------+---------+-----------+-------------+----------+-------+----------------+
| node        | story  |       0 |       264 |         264 | und      |     0 |           NULL |
| node        | story  |       0 |       453 |         453 | und      |     0 |           NULL |
| node        | story  |       0 |       528 |         528 | und      |     0 |           NULL |
| node        | story  |       0 |      1070 |        1070 | und      |     0 |           NULL |
| node        | story  |       0 |      1117 |        1117 | und      |     0 |           NULL |
| node        | story  |       0 |      2368 |        2368 | und      |     0 |           NULL |
| node        | story  |       0 |      2891 |        2892 | und      |     0 |           NULL |
| node        | story  |       0 |      4237 |        4238 | und      |     0 |           NULL |
| node        | story  |       0 |      5718 |        5731 | und      |     0 |           NULL |
| node        | story  |       0 |      6588 |        6601 | und      |     0 |           NULL |
| node        | story  |       0 |      7928 |        7946 | und      |     0 |           NULL |
| node        | story  |       0 |      9041 |        9059 | und      |     0 |           NULL |
| node        | story  |       0 |      9137 |        9155 | und      |     0 |           NULL |
| node        | story  |       0 |      9138 |        9156 | und      |     0 |           NULL |
| node        | story  |       0 |      9168 |        9186 | und      |     0 |           NULL |
+-------------+--------+---------+-----------+-------------+----------+-------+----------------+
15 rows in set (0.00 sec)

What is interesting about this data is that I used node_convert to convert all my story nodes to article nodes, and field_tags never existed for the story content type, so I guess this might be a node_convert issue. If I edit and save the node without making changes the row in this table is removed and the error goes away.

I wonder if it's worth checking that the tid value isn't NULL in taxonomy_field_formatter_prepare_view()?

I've just found #1102570: array_flip() [function.array-flip] issue in DrupalDefaultEntityController / entity.inc which is probably a more appropriate issue? Patch in #26 over there is a generic way to solve this.

That issue seems to talk only about D7. If this is still an issue in D8, then either that issue needs to be moved there, or this issue needs a patch to fix it in D8.

Just fixing up 1 view does not seem like the right solution, unless that's the only place its a problem in D8.

Found this on my installation. Looks like taxonomy_field_formatter_prepare_view() doesn't properly check to make sure the tids it attempts to load are numeric; you'll see that taxonomy_term_load does do a check for this before it calls taxonomy_term_load_multiple. I think it makes sense to do this check here too, since we're calling that function as well.

This affects D8 and D7.

The patch in #1 may be wider reaching than this needs to be. This could be an extremely simple one-liner.

Patch for D8.

Actually, reading through the code and documentation more, the patch in #1 was right in unsetting the term from $items. However, I think it's worth keeping with the use of is_numeric since that's what's used in taxonomy_term_load().

New patch for review.

For Drupal 7.

Tests are awesome.

Updating issue to use issue summary template.

#9: d8-array_flip_taxonomy_field_formatter_prepare_view-1470236-9.patch queued for re-testing.

Getting rid of user specific directory in the error string.

Patch upated.

Still needs tests. Also, the patch in #13 isn't valid for D8, see https://www.drupal.org/node/1805846

I'm going to take this one on.

I'm first going to attempt to establish whether this is still an issue in D8.

These are the steps I have followed on a clean install of 8.0.x:

Create new article node (/node/add/article) and leave Tags field empty and save.
Result: no entry in the node__field_tags table.

Edit node (/node/1/edit) and add a tag 'Tag one' and save.
Result: 1 entry in the node__field_tags table.

Delete the 'Tag one' term (/admin/structure/taxonomy/manage/tags/overview).
Visit node/1
Result: Fatal error: Call to a member function getName() on a non-object in /vagrant_sites/drupal8.local/web/core/modules/taxonomy/src/Plugin/Field/FieldFormatter/LinkFormatter.php on line 45
and
1 entry remains in the node__field_tags table with a value in field_tags_target_id column.

I believe this is a different issue which I will report if I cannot find it in the issue queue. But I can not reproduce this bug.

Any help? @jhedstrom @iamEAP

After #1847596: Remove Taxonomy term reference field in favor of Entity reference taxonomy term field is gone. This is no longer a bug in D8. Moving back to D7.

One place where I've seen this bug is if the entity that has the taxonomy term field attached has gone through a form rebuild (e.g. after a validation error) and the form was submitted with no terms selected - then https://api.drupal.org/api/drupal/modules!field!field.default.inc/functi... winds up taking empty NULL values from $form_state['values'] and polluting the entity with those values. So that is how you wind up with a NULL entry for the 'tid'.

So in that case, at least, it seems like a deeper bug with the field system or form API, nothing specific to taxonomy terms. I'm not sure if that still affects Drupal 8 or not.

I think this issue can be related to: #873722: 'autocreate' == 0 . Will see if this would be reproducible after that related issue will be fixed.

This was not fixed by the mentioned issue. The array_flip warning is still present if you have a NULL value in the TID column in the database and you open the taxonomy term detail.

Warning: array_flip(): Can only flip string and integer values, entry skipped in DrupalDefaultEntityController->load() (line 175 of /includes/entity.inc).

As it was mentioned, problem is in the taxonomy_field_formatter_prepare_view() function with this loading: $terms = taxonomy_term_load_multiple($tids); if the $tids array contains NULLs.

I think this can be solved most easily by adding an array_filter() to the $tids array - this will filter out NULLs. Then the NULLs will be removed also from the $items array few lines below (so do not need to duplicate the same code here, like the patch #1 was doing):

unset($items[$id][$delta]);
$rekey = TRUE;

Adding a patch with this array_filter() approach and also added the test with the failure (no interdiff as this is completely different approach).

We have used similar fix in this issue: #3006007: Don't try to load the user picture if it's not set. Adding a tag for the other maintainer review.

I could go either way with whether we avoid putting the entries into the $tids array in the preceding loop, or filter them out when passing the list to taxonomy_term_load_multiple() per the last patch.

I don't think there's much difference, but this approach is simple.

I can't see how it would cause problems as presumably taxonomy_term_load_multiple() was never going to return anything for the null elements.

Thanks for adding tests!

I think this looks good and is ready to commit.

Committed, thanks everyone!