Set process.element to null on corpus processes before corpus deletion

closes #1476 (closed)

arkindex/documents/tasks.py

@@ -41,6 +41,10 @@ def corpus_delete(corpus_id: str) -> None:
         corpus.top_level_type_id = None
         corpus.save(update_fields=["top_level_type_id"])
 
+    # Set process.element to NULL in all processes, to avoid IntegrityErrors when deleting elements, as
+    # elements are deleted before processes.
+    Process.objects.filter(corpus_id=corpus_id).exclude(element_id=None).update(element_id=None)
+
     # Delete all related objects, bypassing RESTRICTs deletion rules
     # and Django's way of loading everything into memory before deleting.
     querysets = [