mediagoblin/media_types/image/migrations.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 import json
  17
  18 from sqlalchemy import MetaData, Column, ForeignKey
  19
  20 from mediagoblin.db.migration_tools import RegisterMigration, inspect_table
  21
  22
  23 MIGRATIONS = {}
  24
  25 @RegisterMigration(1, MIGRATIONS)
  26 def remove_gps_from_image(db):
  27     """
  28     This will remove GPS coordinates from the image model to put them
  29     on the new Location model.
  30     """
  31     metadata = MetaData(bind=db.bind)
  32     image_table = inspect_table(metadata, "image__mediadata")
  33     location_table = inspect_table(metadata, "core__locations")
  34     media_entries_table = inspect_table(metadata, "core__media_entries")
  35
  36     # First do the data migration
  37     for row in db.execute(image_table.select()):
  38         fields = {
  39             "longitude": row.gps_longitude,
  40             "latitude": row.gps_latitude,
  41             "altitude": row.gps_altitude,
  42             "direction": row.gps_direction,
  43         }
  44
  45         # Remove empty values
  46         for k, v in fields.items():
  47             if v is None:
  48                 del fields[k]
  49
  50         # No point in adding empty locations
  51         if not fields:
  52             continue
  53
  54         # JSONEncoded is actually a string field just json.dumped
  55         # without the ORM we're responsible for that.
  56         fields = json.dumps(fields)
  57
  58         location = db.execute(location_table.insert().values(position=fields))
  59
  60         # now store the new location model on Image
  61         db.execute(media_entries_table.update().values(
  62             location=location.inserted_primary_key[0]
  63         ).where(media_entries_table.c.id==row.media_entry))
  64
  65     db.commit()
  66
  67     # All that data has been migrated across lets remove the fields
  68     image_table.columns["gps_longitude"].drop()
  69     image_table.columns["gps_latitude"].drop()
  70     image_table.columns["gps_altitude"].drop()
  71     image_table.columns["gps_direction"].drop()
  72
  73     db.commit()