Content metatag default values do not appear in the metatag field

I did some debugging on this issue.
It's more an UI display issue - calling the node page directly shows the correct default values provided for a given entity type.
Even if you enter some custom values in the metatags field, those values are correct on the node (view) page.

The problem is, that the metatag_get_route_entity function does not return an EntityInterface cause the route node.add is not processed correctly in here.

Thank you for the hint Steffen! I managed it to get this working for nodes but I'm not sure whether this could work for other bundable entity types because of the '/(.*)\.add/' route, I doubt that other developers use always that pattern for creating an entity with a specific bundle.

Patch works as designed for new content. I wonder why the test is failing?

I think the tests should confirm the fields are present on the form.

Looking at that now.

Fatal error: Call to a member function id() on a non-object in /Applications/MAMP/htdocs/drupal-8/modules/metatag/src/Tests/MetatagFieldTest.php on line 113
FATAL Drupal\metatag\Tests\MetatagFieldTest: test runner returned a non-zero error code (255).
Drupal\metatag\Tests\MetatagFieldTest                          0 passes   1 fails                            
- Found database prefix 'simpletest458607' for test ID 29.
[09-Jul-2016 01:05:19 Australia/Sydney] Uncaught PHP Exception Drupal\Component\Plugin\Exception\PluginNotFoundException: "The "entity.entity_test" entity type does not exist." at /Applications/MAMP/htdocs/drupal-8/core/lib/Drupal/Core/Entity/EntityTypeManager.php line 125
[09-Jul-2016 01:05:19 Australia/Sydney] PHP Fatal error:  Call to a member function id() on a non-object in /Applications/MAMP/htdocs/drupal-8/modules/metatag/src/Tests/MetatagFieldTest.php on line 113

I have looked for a half hour and have no idea why this test would fail. It can't find the "entity_test" entity type.

With this patch enabled with beta9 we can't create taxonomy terms any more.

Rerolled.

Ok, changing MetatagFieldTest so that every drupalPostForm() call is preceded by a drupalGet() to confirm the form loads in the first place.

So the failure is loading the form in the first place, which suggests that the patch breaks something in how the "entity_test" entity is loaded.

It's a little kludgy, but I'm not sure what the appropriate solution is. This removes occurrences of "entity." from the $entity_type string, but now results in:
Fatal error: Call to a member function bundle() on null in metatag.module on line 179

This doesn't fully resolve the problem anyway, because the form doesn't overwrite global values unless they're empty, e.g.:

This is causing the tests in #2775441: Replace deprecated entity_load and entity_create with appropriate methods to fail.

Lets fix this for the next release.

Skipping the $type variable if it's empty.

Moving the (minor) test changes into #2780109: Update all tests so drupalGet() runs before drupalPostForm().

Just the changes to metatag.module.

I've committed this so that I can then commit #2775441: Replace deprecated entity_load and entity_create with appropriate methods.

.. but this still needs more work and tests to confirm that the correct default values are being loaded.

These tests should pass, but they won't.

This happens because of the usage of array_merge() to combine the various levels of defaults. So that needs to be fixed.

So in formElement() on a node/add/article form (which has a Metatag field) it has already loaded the global values into the $items object. Not sure why this is happening, anyone have any ideas?

Ah! I dug into the data in the {config} table and it seems that the global defaults are being saved into field.field.[entitytype].field_[fieldname] in default_value[0]['value']. So that's the problem.

Lets see if this fixes it - it changes metatag_form_field_config_edit_form_alter() so that it sets $form['default_value']['widget'] to NULL, hopefully blocking out any default values from being saved.

Lets see if this works.

Somehow changing the defaults to NULL is making it throw an "Unsupported operand types" error in getFieldTags(). Lets try an empty array as the default value instead of NULL.

So, maybe we just need to skip the unserialize() step if the string is empty?

A slightly better approach - instead of erasing the entire default_value structure, just erase each individual '#default_value' value.

People who are more familiar with the D8 APIs - is #41 a reasonable approach to this problem, where we don't actually want to store a field's default values at the field level so that it may be inherited from the global configurations instead?

Committed. Thanks all!

@Damien, I have the latest beta but I still see this problem on a clean install. I am getting the global tokens instead of the content tokens.

Yeah, unfortunately, same here, as well... seeing global tokens instead of content tokens :/

Edit: Actually I just tried (and looked at the code of) the dev version, and this has been fixed :)

Please test the latest -dev release, this was fixed in #2817309: Metatag shows predefined global values every time in forms (with tests!).