Add image ancestry and update the test db accordingly.

data/model.py

@@ -198,7 +198,7 @@ def set_image_checksum(image_id, repository, checksum):
 
 
 def set_image_metadata(image_id, namespace_name, repository_name,
-                       created_date_str, comment):
+                       created_date_str, comment, parent=None):
   joined = Image.select().join(Repository)
   image_list = list(joined.where(Repository.name == repository_name,
                                  Repository.namespace == namespace_name,
@@ -210,6 +210,10 @@ def set_image_metadata(image_id, namespace_name, repository_name,
   fetched = image_list[0]
   fetched.created = dateutil.parser.parse(created_date_str)
   fetched.comment = comment
+
+  if parent:
+    fetched.ancestors = '%s%s/' % (parent.ancestors, parent.id)
+
   fetched.save()
   return fetched
 
@@ -220,15 +224,6 @@ def get_repository_images(namespace_name, repository_name):
                       Repository.namespace == namespace_name)
 
 
-def get_tag_images(namespace_name, repository_name, tag_name):
-  joined = Image.select().join(RepositoryTag).join(Repository)
-  fetched = list(joined.where(Repository.name == repository_name,
-                              Repository.namespace == namespace_name,
-                              RepositoryTag.name == tag_name))
-
-  return fetched
-
-
 def list_repository_tags(namespace_name, repository_name):
   select = RepositoryTag.select(RepositoryTag, Image)
   with_repo = select.join(Repository)
@@ -238,13 +233,33 @@ def list_repository_tags(namespace_name, repository_name):
 
 
 def get_tag_image(namespace_name, repository_name, tag_name):
-  fetched = get_tag_images(namespace_name, repository_name, tag_name)
+  joined = Image.select().join(RepositoryTag).join(Repository)
+  fetched = joined.where(Repository.name == repository_name,
+                         Repository.namespace == namespace_name,
+                         RepositoryTag.name == tag_name)
+
   if not fetched:
     raise DataModelException('Unable to find image for tag.')
 
   return fetched[0]
 
 
+def get_image_by_id(image_id):
+  return Image.get(Image.image_id == image_id)
+
+
+def get_parent_images(image_obj):
+  """ Returns a list of parent Image objects in chronilogical order. """
+  parents = image_obj.ancestors
+  parent_db_ids = parents.strip('/').split('/')
+
+  or_clauses = [(Image.id == db_id) for db_id in parent_db_ids]
+  parent_images = Image.select().where(reduce(operator.or_, or_clauses))
+  id_to_image = {unicode(image.id): image for image in parent_images}
+
+  return [id_to_image[parent_id] for parent_id in parent_db_ids]
+
+
 def create_or_update_tag(namespace_name, repository_name, tag_name,
                          tag_image_id):
   repo = Repository.get(Repository.name == repository_name,