Merge pull request #60 from wagtail/tags-and-child-models

Tags and child models

README.md

@@ -65,6 +65,15 @@ The following settings are additionally recognised:
 
   By default, objects referenced within imported content will be recursively imported to ensure that those references are still valid on the destination site. However, this is not always desirable - for example, if this happened for the Page model, this would imply that any pages linked from an imported page would get imported as well, along with any pages linked from _those_ pages, and so on, leading to an unpredictable number of extra pages being added anywhere in the page tree as a side-effect of the import. Models listed in `WAGTAILTRANSFER_NO_FOLLOW_MODELS` will thus be skipped in this process, leaving the reference unresolved. The effect this has on the referencing page will vary according to the kind of relation: nullable foreign keys, one-to-many and many-to-many relations will simply omit the missing object; references in rich text and StreamField will become broken links (just as linking a page and then deleting it would); while non-nullable foreign keys will prevent the object from being created at all (meaning that any objects referencing _that_ object will end up with unresolved references, to be handled by the same set of rules).
 
+* `WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS = [('wagtailimages.image', 'tagged_items')]`
+
+  Specifies a list of models, their reverse relations to follow, and whether deletions should be synced, when identifying object references that should be imported to the destination site. Defaults to `[('wagtailimages.image', 'tagged_items', True)]`.
+
+  By default, Wagtail Transfer will not follow reverse relations (other than importing child models of `ClusterableModel` subclasses) when identifying referenced models. Specifying a `(model, reverse_relationship_name, track_deletions)` in `WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS` means that when
+  encountering that model and relation, Wagtail Transfer will follow the reverse relationship from the specified model and add the models found to the import if they do not exist on the destination site. This is typically useful in cases such as tags on non-Page models. The `track_deletions` boolean,
+  if `True`, will delete any models in the reverse relation on the destination site that do not exist in the source site's reverse relation. As a result,
+  it should only be used for models that behave strictly like child models but do not use `ParentalKey` - for example, tags, where importing an image with deleted tags should delete those tag linking models on the destination site as well.
+
 Note that these settings do not accept models that are defined as subclasses through [multi-table inheritance](https://docs.djangoproject.com/en/stable/topics/db/models/#multi-table-inheritance) - in particular, they cannot be used to define behaviour that only applies to specific subclasses of Page.
 
 * `WAGTAILTRANSFER_CHOOSER_API_PROXY_TIMEOUT = 5`

docs/settings.md

@@ -87,12 +87,30 @@ that object will end up with unresolved references, to be handled by the same se
 Note that these settings do not accept models that are defined as subclasses through multi-table inheritance - in 
 particular, they cannot be used to define behaviour that only applies to specific subclasses of Page.
 
+
+### `WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS`
+
+```python
+WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS = [('wagtailimages.image', 'tagged_items', True)]
+```
+
+Specifies a list of models, their reverse relations to follow, and whether deletions should be synced, when identifying object references that should be imported to the destination site. Defaults to `[('wagtailimages.image', 'tagged_items', True)]`.
+
+By default, Wagtail Transfer will not follow reverse relations (other than importing child models of `ClusterableModel` subclasses) when identifying referenced models. Specifying a `(model, reverse_relationship_name, track_deletions)` in `WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS` means that when
+encountering that model and relation, Wagtail Transfer will follow the reverse relationship from the specified model and add the models found to the import if they do not exist on the destination site. This is typically useful in cases such as tags on non-Page models. The `track_deletions` boolean,
+if `True`, will delete any models in the reverse relation on the destination site that do not exist in the source site's reverse relation. As a result,
+it should only be used for models that behave strictly like child models but do not use `ParentalKey` - for example, tags, where importing an image with deleted tags should delete those tag linking models on the destination site as well.
+
+
+### `WAGTAILTRANSFER_CHOOSER_API_PROXY_TIMEOUT`
+
 ```python
 WAGTAILTRANSFER_CHOOSER_API_PROXY_TIMEOUT = 5
 ```
 
   By default, each API call made to browse the page tree on the source server has a timeout limit of 5 seconds. If you find this threshold is too low, you can increase it. This may be of particular use if you are running two local runservers to test or extend Wagtail Transfer.
 
+
 ## Hooks
 
 ### `register_field_adapters`

tests/migrations/0016_advert_tags.py

@@ -0,0 +1,20 @@
+# Generated by Django 3.0.5 on 2020-10-16 11:13
+
+from django.db import migrations
+import taggit.managers
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('taggit', '0003_taggeditem_add_unique_index'),
+        ('tests', '0015_longadvert'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='advert',
+            name='tags',
+            field=taggit.managers.TaggableManager(help_text='A comma-separated list of tags.', through='taggit.TaggedItem', to='taggit.Tag', verbose_name='Tags'),
+        ),
+    ]

tests/models.py

@@ -1,5 +1,6 @@
 from django.db import models
 from modelcluster.fields import ParentalKey, ParentalManyToManyField
+from taggit.managers import TaggableManager
 from wagtail.core.fields import RichTextField, StreamField
 from wagtail.core.models import Orderable, Page
 from wagtail.snippets.models import register_snippet
@@ -13,6 +14,7 @@ class SimplePage(Page):
 
 class Advert(models.Model):
     slogan = models.CharField(max_length=255)
+    tags = TaggableManager()
 
 
 class LongAdvert(Advert):

tests/settings.py

@@ -134,6 +134,8 @@
     }
 }
 
+WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS = [('wagtailimages.image', 'tagged_items', True), ('tests.advert', 'tagged_items', True)]
+
 WAGTAILTRANSFER_SECRET_KEY = 'i-am-the-local-secret-key'
 
 WAGTAILTRANSFER_UPDATE_RELATED_MODELS = ['wagtailimages.Image', 'tests.advert']

tests/tests/test_api.py

@@ -195,15 +195,17 @@ def test_parental_keys(self):
         data = json.loads(response.content)
 
         page_data = None
+        section_data = []
         for obj in data['objects']:
             if obj['model'] == 'tests.sectionedpage' and obj['pk'] == page.pk:
                 page_data = obj
-                break
+            if obj['model'] == 'tests.sectionedpagesection':
+                section_data.append(obj)
 
         self.assertEqual(len(page_data['fields']['sections']), 2)
-        self.assertEqual(page_data['fields']['sections'][0]['model'], 'tests.sectionedpagesection')
-        self.assertEqual(page_data['fields']['sections'][0]['fields']['title'], "Create the universe")
-        section_id = page_data['fields']['sections'][0]['pk']
+        self.assertEqual(section_data[0]['model'], 'tests.sectionedpagesection')
+        self.assertTrue(section_data[0]['fields']['title'] == "Create the universe")
+        section_id = page_data['fields']['sections'][0]
 
         # there should also be a uid mapping for the section
         matching_uids = [
@@ -529,6 +531,21 @@ def test_model_with_multi_table_inheritance(self):
         self.assertEqual(data['objects'][0]['model'], 'tests.longadvert')
         # the child object should be serialized
 
+    def test_model_with_tags(self):
+        # test that a reverse relation such as tagged_items is followed to obtain references to the
+        # tagged_items, if the model and relationship are specified in WAGTAILTRANSFER_FOLLOWED_REVERSE_RELATIONS
+        ad = Advert.objects.create(slogan='test')
+        ad.tags.add('test_tag')
+
+        response = self.get({
+            'tests.advert': [ad.pk]
+        })
+        self.assertEqual(response.status_code, 200)
+        data = json.loads(response.content)
+
+        mapped_models = {mapping[0] for mapping in data['mappings']}
+        self.assertIn('taggit.taggeditem', mapped_models)
+
     def test_image(self):
         with open(os.path.join(FIXTURES_DIR, 'wagtail.jpg'), 'rb') as f:
             image = Image.objects.create(