Migration documents.0037_delete_documentresourcelink may fail

[etj]

The migration adds a linkedResource to each document having an associated DocumentResourceLink.

It happened that the migration failed in an instance because the related Resource was not found;

here the log

   Applying documents.0037_delete_documentresourcelink...Traceback (most recent call last):
   File "/usr/local/lib/python3.10/dist-packages/django/db/backends/base/base.py", line 313, in _commit
     return self.connection.commit()
 psycopg2.errors.ForeignKeyViolation: insert or update on table "base_linkedresource" violates foreign key constraint "base_linkedresource_target_id_90785fa2_fk_base_resourcebase_id"
 DETAIL:  Key (target_id)=(181) is not present in table "base_resourcebase".
 
 
 The above exception was the direct cause of the following exception:
 
 Traceback (most recent call last):
   File "/usr/src/masdap/manage.py", line 31, in <module>
     execute_from_command_line(sys.argv)
   File "/usr/local/lib/python3.10/dist-packages/django/core/management/__init__.py", line 442, in execute_from_command_line
     utility.execute()
   File "/usr/local/lib/python3.10/dist-packages/django/core/management/__init__.py", line 436, in execute
     self.fetch_command(subcommand).run_from_argv(self.argv)
   File "/usr/local/lib/python3.10/dist-packages/django/core/management/base.py", line 412, in run_from_argv
     self.execute(*args, **cmd_options)
   File "/usr/local/lib/python3.10/dist-packages/django/core/management/base.py", line 458, in execute
     output = self.handle(*args, **options)
   File "/usr/local/lib/python3.10/dist-packages/django/core/management/base.py", line 106, in wrapper
     res = handle_func(*args, **kwargs)
   File "/usr/local/lib/python3.10/dist-packages/django/core/management/commands/migrate.py", line 356, in handle
     post_migrate_state = executor.migrate(
   File "/usr/local/lib/python3.10/dist-packages/django/db/migrations/executor.py", line 135, in migrate
     state = self._migrate_all_forwards(
   File "/usr/local/lib/python3.10/dist-packages/django/db/migrations/executor.py", line 167, in _migrate_all_forwards
     state = self.apply_migration(
   File "/usr/local/lib/python3.10/dist-packages/django/db/migrations/executor.py", line 249, in apply_migration
     with self.connection.schema_editor(
   File "/usr/local/lib/python3.10/dist-packages/django/db/backends/base/schema.py", line 168, in __exit__
     self.atomic.__exit__(exc_type, exc_value, traceback)
   File "/usr/local/lib/python3.10/dist-packages/django/db/transaction.py", line 263, in __exit__
     connection.commit()
   File "/usr/local/lib/python3.10/dist-packages/django/utils/asyncio.py", line 26, in inner
     return func(*args, **kwargs)
   File "/usr/local/lib/python3.10/dist-packages/django/db/backends/base/base.py", line 337, in commit
     self._commit()
   File "/usr/local/lib/python3.10/dist-packages/django/db/backends/base/base.py", line 312, in _commit
     with debug_transaction(self, "COMMIT"), self.wrap_database_errors:
   File "/usr/local/lib/python3.10/dist-packages/django/db/utils.py", line 91, in __exit__
     raise dj_exc_value.with_traceback(traceback) from exc_value
   File "/usr/local/lib/python3.10/dist-packages/django/db/backends/base/base.py", line 313, in _commit
     return self.connection.commit()
 django.db.utils.IntegrityError: insert or update on table "base_linkedresource" violates foreign key constraint "base_linkedresource_target_id_90785fa2_fk_base_resourcebase_id"
 DETAIL:  Key (target_id)=(181) is not present in table "base_resourcebase".

This may probably be caused by the linked layers to have been removed, and the link was not removed accordingly (was there a signal?). The DB did not have a FK on the resource, because the linked object could be anything -- on the DB where the error happened the linked resources were layers:

DB content details

select * from documents_documentresourcelink link 
where not exists (select * from base_resourcebase br where link.object_id  = br.id )

results:

id|object_id|content_type_id|document_id|
--+---------+---------------+-----------+
26|      181|             41|        271|
34|        5|             41|        252|
35|        5|             41|        256|

The 3 resources have type 41:

select * from django_content_type where id = 41

id|app_label|model  |
--+---------+-------+
41|layers   |dataset|

The migration should exclude links that have no existing target.

Found on GeoNode 4.3.1