Fix reverse accessor clashes.

closes #5479
https://pulp.plan.io/issues/5479

README.md

@@ -115,8 +115,7 @@ from Pulp 2 to Pulp 3, here are some guidelines.
 4. Add a Content model to pre-migrate Pulp 2 content to (subclass the provided `Pulp2to3Content` 
 class). It has to have:
  - a field `type` which will correspond to the `_content_type_id` of your Content in Pulp 2.
- - a ForeignKey to the `pulp_2to3_migrate.app.models.Pulp2Content` model with the `related_name` 
- set to `'detail_model'` (provided by `Pulp2to3Content`).
+ - on a Meta class a `default_related_name` set to `<your pulp 2 content type>_detail_model`
  - a classmethod `pre_migrate_content_detail` (see `Pulp2to3Content` for more details)
  - a classmethod `migrate_content_to_pulp3` (see `Pulp2to3Content` for more details)
  - a method `create_pulp3_content` (see `Pulp2to3Content` for more details)
@@ -129,4 +128,4 @@ class). It has to have:
  artifact creation.
 
  5. Subclass the provided `Pulp2to3Importer` class and define `migrate_to_pulp3` method which
-  create a plugin Remote instance based on the provided pre-migrated `Pulp2Importer`. 
+  create a plugin Remote instance based on the provided pre-migrated `Pulp2Importer`.

pulp_2to3_migrate/app/models/content.py

@@ -31,13 +31,17 @@ class Meta:
         unique_together = ('pulp2_id', 'pulp2_content_type_id')
 
 
+    @property
+    def detail_model(self):
+        return getattr(self, f'{self.pulp2_content_type_id}_detail_model').get()
+
+
 class Pulp2to3Content(Model):
     """
     Pulp 2to3 detail content model to store pulp 2 content details for Pulp 3 content creation.
     """
-    pulp2content = models.ForeignKey(Pulp2Content,
-                                     related_name='detail_model',
-                                     on_delete=models.CASCADE)
+    pulp2content = models.ForeignKey(Pulp2Content, on_delete=models.CASCADE)
+
     type = '<your pulp 2 content type>'
 
     class Meta:

pulp_2to3_migrate/app/plugin/content.py

@@ -170,7 +170,7 @@ async def migrate_to_pulp3(self, batch, pb=None):
             batch: A batch of Pulp2Content objects to migrate to Pulp 3
         """
         for pulp2content in batch:
-            pulp_2to3_detail_content = pulp2content.detail_model.get()
+            pulp_2to3_detail_content = pulp2content.detail_model
             pulp3content = pulp_2to3_detail_content.create_pulp3_content()
             future_relations = {'pulp2content': pulp2content}
 

pulp_2to3_migrate/app/plugin/iso/pulp3/models.py

@@ -24,6 +24,7 @@ class Pulp2ISO(Pulp2to3Content):
 
     class Meta:
         unique_together = ('name', 'checksum', 'size', 'pulp2content')
+        default_related_name = 'iso_detail_model'
 
     @property
     def expected_digests(self):