Add management commands to merge editions and authors

bookwyrm/management/commands/merge_authors.py

@@ -0,0 +1,12 @@
+""" PROCEED WITH CAUTION: uses deduplication fields to permanently
+merge author data objects """
+from bookwyrm import models
+from bookwyrm.management.merge_command import MergeCommand
+
+
+class Command(MergeCommand):
+    """merges two authors by ID"""
+
+    help = "merges specified authors into one"
+
+    MODEL = models.Author

bookwyrm/management/commands/merge_editions.py

@@ -0,0 +1,12 @@
+""" PROCEED WITH CAUTION: uses deduplication fields to permanently
+merge edition data objects """
+from bookwyrm import models
+from bookwyrm.management.merge_command import MergeCommand
+
+
+class Command(MergeCommand):
+    """merges two editions by ID"""
+
+    help = "merges specified editions into one"
+
+    MODEL = models.Edition

bookwyrm/management/merge_command.py

@@ -0,0 +1,30 @@
+from bookwyrm.management.merge import merge_objects
+from django.core.management.base import BaseCommand
+
+
+class MergeCommand(BaseCommand):
+    """base class for merge commands"""
+
+    def add_arguments(self, parser):
+        """add the arguments for this command"""
+        parser.add_argument("--canonical", type=int, required=True)
+        parser.add_argument("--other", type=int, required=True)
+
+    # pylint: disable=no-self-use,unused-argument
+    def handle(self, *args, **options):
+        """merge the two objects"""
+        model = self.MODEL
+
+        try:
+            canonical = model.objects.get(id=options["canonical"])
+        except model.DoesNotExist:
+            print("canonical book doesn’t exist!")
+            return
+        try:
+            other = model.objects.get(id=options["other"])
+        except model.DoesNotExist:
+            print("other book doesn’t exist!")
+            return
+
+        merge_objects(canonical, other)
+