Empty channels publish handling

contentcuration/contentcuration/models.py

@@ -1971,6 +1971,9 @@ def copy_to(
     def copy(self):
         return self.copy_to()
 
+    def is_publishable(self):
+        return self.complete and self.get_descendants(include_self=True).exclude(kind_id=content_kinds.TOPIC).exists()
+
     class Meta:
         verbose_name = "Topic"
         verbose_name_plural = "Topics"

contentcuration/contentcuration/tests/test_exportchannel.py

@@ -9,6 +9,7 @@
 from django.core.management import call_command
 from django.db import connections
 from kolibri_content import models as kolibri_models
+from kolibri_content.router import cleanup_content_database_connection
 from kolibri_content.router import get_active_content_database
 from kolibri_content.router import set_active_content_database
 from le_utils.constants import exercises
@@ -28,6 +29,7 @@
 from .testdata import slideshow
 from .testdata import thumbnail_bytes
 from contentcuration import models as cc
+from contentcuration.utils.publish import ChannelIncompleteError
 from contentcuration.utils.publish import convert_channel_thumbnail
 from contentcuration.utils.publish import create_content_database
 from contentcuration.utils.publish import create_slideshow_manifest
@@ -216,8 +218,7 @@ def setUp(self):
 
     def tearDown(self):
         # Clean up datbase connection after the test
-        connections[self.tempdb].close()
-        del connections.databases[self.tempdb]
+        cleanup_content_database_connection(self.tempdb)
         super(ExportChannelTestCase, self).tearDown()
         set_active_content_database(None)
         if os.path.exists(self.tempdb):
@@ -429,6 +430,29 @@ def test_publish_no_modify_legacy_exercise_extra_fields(self):
         })
 
 
+class EmptyChannelTestCase(StudioTestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        super(EmptyChannelTestCase, cls).setUpClass()
+        cls.patch_copy_db = patch('contentcuration.utils.publish.save_export_database')
+        cls.patch_copy_db.start()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(EmptyChannelTestCase, cls).tearDownClass()
+        cls.patch_copy_db.stop()
+
+    def test_publish_empty_channel(self):
+        content_channel = channel()
+        set_channel_icon_encoding(content_channel)
+        content_channel.main_tree.complete = True
+        content_channel.main_tree.save()
+        content_channel.main_tree.get_descendants().exclude(kind_id="topic").delete()
+        with self.assertRaises(ChannelIncompleteError):
+            create_content_database(content_channel, True, self.admin_user.id, True)
+
+
 class ChannelExportUtilityFunctionTestCase(StudioTestCase):
     @classmethod
     def setUpClass(cls):

contentcuration/contentcuration/utils/publish.py

@@ -74,6 +74,10 @@ class NoNodesChangedError(Exception):
     pass
 
 
+class ChannelIncompleteError(Exception):
+    pass
+
+
 class SlowPublishError(Exception):
     """
     Used to track slow Publishing operations. We don't raise this error,
@@ -195,8 +199,8 @@ def __init__(
         force_exercises=False,
         progress_tracker=None,
     ):
-        if not root_node.complete:
-            raise ValueError("Attempted to publish a channel with an incomplete root node")
+        if not root_node.is_publishable():
+            raise ChannelIncompleteError("Attempted to publish a channel with an incomplete root node or no resources")
 
         self.root_node = root_node
         task_percent_total = 80.0
@@ -220,7 +224,7 @@ def recurse_nodes(self, node, inherited_fields):  # noqa C901
         logging.debug("Mapping node with id {id}".format(id=node.pk))
 
         # Only process nodes that are either non-topics or have non-topic descendants
-        if node.get_descendants(include_self=True).exclude(kind_id=content_kinds.TOPIC).exists() and node.complete:
+        if node.is_publishable():
             # early validation to make sure we don't have any exercises without mastery models
             # which should be unlikely when the node is complete, but just in case
             if node.kind_id == content_kinds.EXERCISE:

contentcuration/contentcuration/viewsets/channel.py

@@ -40,6 +40,7 @@
 from contentcuration.utils.garbage_collect import get_deleted_chefs_root
 from contentcuration.utils.pagination import CachedListPagination
 from contentcuration.utils.pagination import ValuesViewsetPageNumberPagination
+from contentcuration.utils.publish import ChannelIncompleteError
 from contentcuration.utils.publish import publish_channel
 from contentcuration.utils.sync import sync_channel
 from contentcuration.viewsets.base import BulkListSerializer
@@ -503,6 +504,13 @@ def publish(self, pk, version_notes="", language=None):
                         }, channel_id=channel.id
                     ),
                 ], applied=True)
+            except ChannelIncompleteError:
+                Change.create_changes([
+                    generate_update_event(
+                        channel.id, CHANNEL, {"publishing": False}, channel_id=channel.id
+                    ),
+                ], applied=True)
+                raise ValidationError("Channel is not ready to be published")
             except Exception:
                 Change.create_changes([
                     generate_update_event(

contentcuration/kolibri_content/router.py

@@ -72,6 +72,16 @@ def get_content_database_connection(alias=None):
     return connections[alias].connection
 
 
+def cleanup_content_database_connection(alias):
+    try:
+        connection = connections[alias]
+        connection.close()
+        del connections.databases[alias]
+    except (ConnectionDoesNotExist, KeyError):
+        # Already cleaned up, nothing to do here!
+        pass
+
+
 class ContentDBRouter(object):
     """A router that decides what content database to read from based on a thread-local variable."""
 
@@ -158,6 +168,7 @@ def __enter__(self):
 
     def __exit__(self, exc_type, exc_value, traceback):
         set_active_content_database(self.previous_alias)
+        cleanup_content_database_connection(self.alias)
 
     def __call__(self, querying_func):
         # allow using the context manager as a decorator

contentcuration/kolibri_public/tests/test_mapper.py

@@ -2,9 +2,9 @@
 import tempfile
 
 from django.core.management import call_command
-from django.db import connections
 from django.test import TestCase
 from kolibri_content import models as kolibri_content_models
+from kolibri_content.router import cleanup_content_database_connection
 from kolibri_content.router import get_active_content_database
 from kolibri_content.router import using_content_database
 from kolibri_public import models as kolibri_public_models
@@ -116,8 +116,7 @@ def test_map_replace(self):
     @classmethod
     def tearDownClass(cls):
         # Clean up datbase connection after the test
-        connections[cls.tempdb].close()
-        del connections.databases[cls.tempdb]
+        cleanup_content_database_connection(cls.tempdb)
         super(ChannelMapperTest, cls).tearDownClass()
         if os.path.exists(cls.tempdb):
             os.remove(cls.tempdb)