Add DB Mixin classes and use them

A bunch of functions on the db objects are really more like
"utility functions": They could live outside the classes
and be called "by hand" passing the appropiate reference.
They usually only use the public API of the object and
rarely use database related stuff.

Goals:
- First, simple: Share the code with the SQL objects, so
  that the code doesn't need to be duplicated.
- Second, it might unclutter the db models and make them
  more into "model only" stuff.
- Doesn't really hurt.

1 files changed, 90 insertions, 0 deletions

diff --git a/mediagoblin/db/mixin.py b/mediagoblin/db/mixin.py
new file mode 100644
index 00000000..4fb325d2
--- /dev/null
+++ b/mediagoblin/db/mixin.py
@@ -0,0 +1,90 @@
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2011,2012 MediaGoblin contributors.  See AUTHORS.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+This module contains some Mixin classes for the db objects.
+
+A bunch of functions on the db objects are really more like
+"utility functions": They could live outside the classes
+and be called "by hand" passing the appropiate reference.
+They usually only use the public API of the object and
+rarely use database related stuff.
+
+These functions now live here and get "mixed in" into the
+real objects.
+"""
+
+from mediagoblin.auth import lib as auth_lib
+from mediagoblin.tools import common
+
+
+class UserMixin(object):
+    def check_login(self, password):
+        """
+        See if a user can login with this password
+        """
+        return auth_lib.bcrypt_check_password(
+            password, self.pw_hash)
+
+
+class MediaEntryMixin(object):
+    def get_display_media(self, media_map,
+                          fetch_order=common.DISPLAY_IMAGE_FETCHING_ORDER):
+        """
+        Find the best media for display.
+
+        Args:
+        - media_map: a dict like
+          {u'image_size': [u'dir1', u'dir2', u'image.jpg']}
+        - fetch_order: the order we should try fetching images in
+
+        Returns:
+        (media_size, media_path)
+        """
+        media_sizes = media_map.keys()
+
+        for media_size in common.DISPLAY_IMAGE_FETCHING_ORDER:
+            if media_size in media_sizes:
+                return media_map[media_size]
+
+    def main_mediafile(self):
+        pass
+
+    def url_for_self(self, urlgen):
+        """
+        Generate an appropriate url for ourselves
+
+        Use a slug if we have one, else use our '_id'.
+        """
+        uploader = self.get_uploader
+
+        if self.get('slug'):
+            return urlgen(
+                'mediagoblin.user_pages.media_home',
+                user=uploader.username,
+                media=self.slug)
+        else:
+            return urlgen(
+                'mediagoblin.user_pages.media_home',
+                user=uploader.username,
+                media=unicode(self._id))
+
+    def get_fail_exception(self):
+        """
+        Get the exception that's appropriate for this error
+        """
+        if self['fail_error']:
+            return common.import_component(self['fail_error'])