Switch to Rendition.filter_spec as the active field for looking up filters

docs/advanced_topics/images/custom_image_model.rst

@@ -45,7 +45,7 @@ Here's an example:
 
         class Meta:
             unique_together = (
-                ('image', 'filter', 'focal_point_key'),
+                ('image', 'filter_spec', 'focal_point_key'),
             )
 
 

docs/releases/1.8.rst

@@ -82,6 +82,29 @@ Bug fixes
 Upgrade considerations
 ======================
 
+``unique_together`` constraint on custom image rendition models needs updating
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If your project is using a custom image model (see :ref:`custom_image_model`), you will need to
+update the ``unique_together`` option on the corresponding Rendition model when upgrading to Wagtail 1.8. Change the line:
+
+.. code-block:: python
+
+    unique_together = (
+        ('image', 'filter', 'focal_point_key'),
+    )
+
+to:
+
+.. code-block:: python
+
+    unique_together = (
+        ('image', 'filter_spec', 'focal_point_key'),
+    )
+
+You will then be able to run ``manage.py makemigrations`` and ``manage.py migrate`` as normal.
+
+
 ``wagtail.wagtailimages.models.get_image_model`` has moved
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

wagtail/wagtailimages/migrations/0016_deprecate_rendition_filter_relation.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.11 on 2016-11-11 17:04
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('wagtailimages', '0015_fill_filter_spec_field'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='rendition',
+            name='filter_spec',
+            field=models.CharField(db_index=True, max_length=255),
+        ),
+        migrations.AlterUniqueTogether(
+            name='rendition',
+            unique_together=set([('image', 'filter_spec', 'focal_point_key')]),
+        ),
+    ]

wagtail/wagtailimages/models.py

@@ -14,7 +14,6 @@ from django.core.files import File
 from django.core.urlresolvers import reverse
 from django.db import models
 from django.db.models.signals import post_delete, pre_save
-from django.db.utils import DatabaseError
 from django.dispatch.dispatcher import receiver
 from django.forms.widgets import flatatt
 from django.utils.encoding import python_2_unicode_compatible
@@ -277,7 +276,7 @@ class AbstractImage(CollectionMember, index.Indexed, models.Model):
 
         try:
             rendition = self.renditions.get(
-                filter=filter,
+                filter_spec=filter.spec,
                 focal_point_key=cache_key,
             )
         except Rendition.DoesNotExist:
@@ -304,7 +303,7 @@ class AbstractImage(CollectionMember, index.Indexed, models.Model):
             output_filename = output_filename_without_extension + '.' + output_extension
 
             rendition, created = self.renditions.get_or_create(
-                filter=filter,
+                filter_spec=filter.spec,
                 focal_point_key=cache_key,
                 defaults={'file': File(generated_image.f, name=output_filename)}
             )
@@ -485,8 +484,8 @@ class Filter(models.Model):
 
 
 class AbstractRendition(models.Model):
-    filter = models.ForeignKey(Filter, related_name='+', null=True, blank=True)
-    filter_spec = models.CharField(max_length=255, db_index=True, blank=True, default='')
+    filter = models.ForeignKey(Filter, related_name='+', null=True, blank=True)  # DEPRECATED - RemovedInWagtail19Warning
+    filter_spec = models.CharField(max_length=255, db_index=True)
     file = models.ImageField(upload_to=get_rendition_upload_to, width_field='width', height_field='height')
     width = models.IntegerField(editable=False)
     height = models.IntegerField(editable=False)
@@ -533,39 +532,23 @@ class AbstractRendition(models.Model):
         filename = self.file.field.storage.get_valid_name(filename)
         return os.path.join(folder_name, filename)
 
-    def save(self, *args, **kwargs):
-        # populate the `filter_spec` field with the spec string of the filter. In Wagtail 1.8
-        # Filter will be dropped as a model, and lookups will be done based on this string instead
-        self.filter_spec = self.filter.spec
-        return super(AbstractRendition, self).save(*args, **kwargs)
-
     @classmethod
     def check(cls, **kwargs):
         errors = super(AbstractRendition, cls).check(**kwargs)
-
-        # If a filter_spec column exists on this model, and contains null entries, warn that
-        # a data migration needs to be performed to populate it
-
-        try:
-            null_filter_spec_exists = cls.objects.filter(filter_spec='').exists()
-        except DatabaseError:
-            # The database is not in a state where the above lookup makes sense;
-            # this is entirely expected, because system checks are performed before running
-            # migrations. We're only interested in the specific case where the column exists
-            # in the db and contains nulls.
-            null_filter_spec_exists = False
-
-        if null_filter_spec_exists:
-            errors.append(
-                checks.Warning(
-                    "Custom image model %r needs a data migration to populate filter_src" % cls,
-                    hint="The database representation of image filters has been changed, and a data "
-                    "migration needs to be put in place before upgrading to Wagtail 1.8, in order to "
-                    "avoid data loss. See http://docs.wagtail.io/en/latest/releases/1.7.html#filter-spec-migration",
-                    obj=cls,
-                    id='wagtailimages.W001',
+        if not cls._meta.abstract:
+            if not any(
+                set(constraint) == set(['image', 'filter_spec', 'focal_point_key'])
+                for constraint in cls._meta.unique_together
+            ):
+                errors.append(
+                    checks.Error(
+                        "Custom rendition model %r has an invalid unique_together setting" % cls,
+                        hint="Custom rendition models must include the constraint "
+                        "('image', 'filter_spec', 'focal_point_key') in their unique_together definition.",
+                        obj=cls,
+                        id='wagtailimages.E001',
+                    )
                 )
-            )
 
         return errors
 
@@ -578,7 +561,7 @@ class Rendition(AbstractRendition):
 
     class Meta:
         unique_together = (
-            ('image', 'filter', 'focal_point_key'),
+            ('image', 'filter_spec', 'focal_point_key'),
         )
 
 

wagtail/wagtailimages/tests/test_models.py

@@ -208,10 +208,8 @@ class TestRenditions(TestCase):
         self.assertEqual(rendition.height, 300)
 
         # check that the rendition has been recorded under the correct filter,
-        # via both the Rendition.filter_spec attribute (which will come into action
-        # in Wagtail 1.8) and the linked Filter model (which will be retired in 1.8)
+        # via the Rendition.filter_spec attribute (in active use as of Wagtail 1.8)
         self.assertEqual(rendition.filter_spec, 'width-400')
-        self.assertEqual(rendition.filter.spec, 'width-400')
 
     def test_resize_to_max(self):
         rendition = self.image.get_rendition('max-100x100')
@@ -487,7 +485,7 @@ class TestIssue312(TestCase):
             IntegrityError,
             Rendition.objects.create,
             image=rend1.image,
-            filter=rend1.filter,
+            filter_spec=rend1.filter_spec,
             width=rend1.width,
             height=rend1.height,
             focal_point_key=rend1.focal_point_key,