Let some code support "media without slug"

The upcoming SQL database will allow having media without a
slug again. This might especially be useful for API
support, where the uploaded image (media) does not have
*any* information to generate a slug from.

This code change mostly allows the sql backend to have no
slug in its model and improves some parts to properly
handle that.

It specifically does not have any web frontend support to
edit/create MediaEntries with no slug.

mediagoblin/db/mixin.py

@@ -63,6 +63,10 @@ class MediaEntryMixin(object):
     def main_mediafile(self):
         pass
 
+    @property
+    def slug_or_id(self):
+        return (self.slug or self._id)
+
     def url_for_self(self, urlgen, **extra_args):
         """
         Generate an appropriate url for ourselves
@@ -71,18 +75,11 @@ class MediaEntryMixin(object):
         """
         uploader = self.get_uploader
 
-        if self.get('slug'):
-            return urlgen(
-                'mediagoblin.user_pages.media_home',
-                user=uploader.username,
-                media=self.slug,
-                **extra_args)
-        else:
-            return urlgen(
-                'mediagoblin.user_pages.media_home',
-                user=uploader.username,
-                media=unicode(self._id),
-                **extra_args)
+        return urlgen(
+            'mediagoblin.user_pages.media_home',
+            user=uploader.username,
+            media=self.slug_or_id,
+            **extra_args)
 
     def get_fail_exception(self):
         """

mediagoblin/db/sql/models.py

@@ -72,7 +72,7 @@ class MediaEntry(Base, MediaEntryMixin):
     id = Column(Integer, primary_key=True)
     uploader = Column(Integer, ForeignKey('users.id'), nullable=False)
     title = Column(Unicode, nullable=False)
-    slug = Column(Unicode, nullable=False)
+    slug = Column(Unicode)
     created = Column(DateTime, nullable=False, default=datetime.datetime.now)
     description = Column(UnicodeText) # ??
     description_html = Column(UnicodeText) # ??

mediagoblin/templates/mediagoblin/user_pages/media.html

@@ -127,7 +127,7 @@
             <a href="{{ request.urlgen('mediagoblin.user_pages.media_home.view_comment',
                    comment = comment._id,
                    user = media.get_uploader.username,
-                   media = media.slug) }}#comment">
+                   media = media.slug_or_id) }}#comment">
               {{ comment.created.strftime("%I:%M%p %Y-%m-%d") }}
             </a>
           </div>