A theoretical set of models to migrate about with, plus one migration ;)

mediagoblin/tests/test_sql_migrations.py

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+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2011 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/>.
+
+import copy
+
+from sqlalchemy import (
+    Table, Column, MetaData,
+    Integer, Unicode, UnicodeText, DateTime, Boolean, ForeignKey,
+    UniqueConstraint, PickleType)
+from sqlalchemy.ext.declarative import declarative_base
+from migrate import changeset
+
+from mediagoblin.db.sql.base import GMGTableBase
+
+
+# This one will get filled with local migrations
+FULL_MIGRATIONS = {}
+
+
+#######################################################
+# Migration set 1: Define initial models, no migrations
+#######################################################
+
+Base1 = declarative_base(cls=GMGTableBase)
+
+class Creature1(Base1):
+    __tablename__ = "creature"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode, unique=True, nullable=False, index=True)
+    num_legs = Column(Integer, nullable=False)
+    is_demon = Column(Boolean)
+
+class Level1(Base1):
+    __tablename__ = "level"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode, unique=True, nullable=False, index=True)
+    description = Column(UnicodeText)
+    exits = Column(PickleType)
+
+SET1_MODELS = [Creature1, Level1]
+
+SET1_MIGRATIONS = []
+
+#######################################################
+# Migration set 2: A few migrations and new model
+#######################################################
+
+Base2 = declarative_base(cls=GMGTableBase)
+
+class Creature2(Base2):
+    __tablename__ = "creature"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode, unique=True, nullable=False, index=True)
+    num_legs = Column(Integer, nullable=False)
+
+class CreaturePower2(Base2):
+    __tablename__ = "creature_power"
+
+    id = Column(Integer, primary_key=True)
+    creature = Column(
+        Integer, ForeignKey('creature.id'), nullable=False)
+    name = Column(Unicode)
+    description = Column(Unicode)
+
+class Level2(Base2):
+    __tablename__ = "level"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode)
+    description = Column(UnicodeText)
+
+class LevelExit2(Base2):
+    __tablename__ = "level_exit"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode)
+    from_level = Column(
+        Integer, ForeignKey('level.id'), nullable=False)
+    to_level = Column(
+        Integer, ForeignKey('level.id'), nullable=False)
+
+SET2_MODELS = [Creature2, CreaturePower2, Level2, LevelExit2]
+
+
+@RegisterMigration(1, FULL_MIGRATIONS)
+def creature_remove_is_demon(db_conn):
+    creature_table = Table(
+        'creature', MetaData(),
+        autoload=True, autoload_with=db_conn.engine)
+    db_conn.execute(
+        creature_table.drop_column('is_demon'))
+    
+
+@RegisterMigration(2, FULL_MIGRATIONS)
+def creature_powers_new_table(db_conn):
+    pass
+
+@RegisterMigration(3, FULL_MIGRATIONS)
+def level_exits_new_table(db_conn):
+    pass
+
+
+# A hack!  At this point we freeze-fame and get just a partial list of
+# migrations
+
+PARTIAL_MIGRATIONS = copy.copy(FULL_MIGRATIONS)
+
+#######################################################
+# Migration set 3: Final migrations
+#######################################################
+
+Base3 = declarative_base(cls=GMGTableBase)
+
+class Creature3(Base3):
+    __tablename__ = "creature"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode, unique=True, nullable=False, index=True)
+    num_limbs= Column(Integer, nullable=False)
+
+class CreaturePower3(Base3):
+    __tablename__ = "creature_power"
+
+    id = Column(Integer, primary_key=True)
+    creature = Column(
+        Integer, ForeignKey('creature.id'), nullable=False, index=True)
+    name = Column(Unicode)
+    description = Column(Unicode)
+
+class Level3(Base3):
+    __tablename__ = "level"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode)
+    description = Column(UnicodeText)
+
+class LevelExit3(Base3):
+    __tablename__ = "level_exit"
+
+    id = Column(Integer, primary_key=True)
+    name = Column(Unicode)
+    from_level = Column(
+        Integer, ForeignKey('level.id'), nullable=False, index=True)
+    to_level = Column(
+        Integer, ForeignKey('level.id'), nullable=False, index=True)
+
+
+SET3_MODELS = [Creature3, CreaturePower3, Level3, LevelExit3]
+
+
+@RegisterMigration(4, FULL_MIGRATIONS)
+def creature_num_legs_to_num_limbs(db_conn):
+    pass
+
+@RegisterMigration(5, FULL_MIGRATIONS)
+def level_exit_index_from_and_to_level(db_conn):
+    pass
+
+@RegisterMigration(6, FULL_MIGRATIONS)
+def creature_power_index_creature(db_conn):
+    pass