pokedex/db/tables.py

   1 # encoding: utf8
   2
   3 from sqlalchemy import Column, ForeignKey, MetaData, Table
   4 from sqlalchemy.ext.declarative import declarative_base
   5 from sqlalchemy.ext.associationproxy import association_proxy
   6 from sqlalchemy.orm import backref, relation
   7 from sqlalchemy.types import *
   8 from sqlalchemy.databases.mysql import *
   9
  10 from pokedex.db import rst
  11
  12 metadata = MetaData()
  13 TableBase = declarative_base(metadata=metadata)
  14
  15 class Ability(TableBase):
  16     __tablename__ = 'abilities'
  17     __singlename__ = 'ability'
  18     id = Column(Integer, primary_key=True, nullable=False)
  19     name = Column(Unicode(24), nullable=False)
  20     flavor_text = Column(Unicode(64), nullable=False)
  21     effect = Column(Unicode(255), nullable=False)
  22
  23 class ContestEffect(TableBase):
  24     __tablename__ = 'contest_effects'
  25     id = Column(Integer, primary_key=True, nullable=False)
  26     appeal = Column(SmallInteger, nullable=False)
  27     jam = Column(SmallInteger, nullable=False)
  28     flavor = Column(Unicode(255), nullable=False)
  29     effect = Column(Unicode(255), nullable=False)
  30
  31 class EggGroup(TableBase):
  32     __tablename__ = 'egg_groups'
  33     id = Column(Integer, primary_key=True, nullable=False)
  34     name = Column(Unicode(16), nullable=False)
  35
  36 class Encounter(TableBase):
  37     """Rows in this table represent encounters with wild Pokémon.
  38
  39     Within a given area in a given game, encounters are differentiated by the
  40     slot they are in and a world condition.
  41
  42     Groups of slots belong to encounter types; these are what the player is
  43     doing to get an encounter, such as surfing or walking through tall grass.
  44
  45     Within an encounter type, slots are defined primarily by rarity.  Each slot
  46     can also be affected by a world condition; for example, the 20% slot for
  47     walking in tall grass is affected by whether a swarm is in effect in the
  48     areas.  "There is a swarm" and "there is not a swarm" are conditions, and
  49     together they make a condition group.  However, since "not a swarm" is a
  50     base state rather than any sort of new state, it is omitted and instead
  51     referred to by a NULL.
  52
  53     A slot (20% walking in grass) and single world condition (NULL, i.e. no
  54     swarm) are thus enough to define a specific encounter.
  55
  56     Well, okay, almost: each slot actually appears twice.
  57     """
  58
  59     __tablename__ = 'encounters'
  60     id = Column(Integer, primary_key=True, nullable=False)
  61     version_id = Column(Integer, ForeignKey('versions.id'), nullable=False, autoincrement=False)
  62     location_area_id = Column(Integer, ForeignKey('location_areas.id'), nullable=False, autoincrement=False)
  63     encounter_type_slot_id = Column(Integer, ForeignKey('encounter_type_slots.id'), nullable=False, autoincrement=False)
  64     encounter_condition_id = Column(Integer, ForeignKey('encounter_conditions.id'), nullable=True, autoincrement=False)
  65     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), nullable=False, autoincrement=False)
  66     min_level = Column(Integer, nullable=False, autoincrement=False)
  67     max_level = Column(Integer, nullable=False, autoincrement=False)
  68
  69 class EncounterCondition(TableBase):
  70     """Rows in this table represent something different about the world that
  71     can affect what Pokémon are encountered.
  72     """
  73
  74     __tablename__ = 'encounter_conditions'
  75     id = Column(Integer, primary_key=True, nullable=False)
  76     encounter_condition_group_id = Column(Integer, ForeignKey('encounter_condition_groups.id'), primary_key=False, nullable=False, autoincrement=False)
  77     name = Column(Unicode(64), nullable=False)
  78
  79 class EncounterConditionGroup(TableBase):
  80     """Rows in this table represent a group of mutually exclusive conditions,
  81     such as morning/day/night.  "Conditions" that are part of the default state
  82     of the world, such as "not during a swarm" or "not using the PokéRadar",
  83     are not included in this table and are referred to by NULLs in other
  84     tables.
  85     """
  86
  87     __tablename__ = 'encounter_condition_groups'
  88     id = Column(Integer, primary_key=True, nullable=False)
  89     name = Column(Unicode(64), nullable=False)
  90
  91 class EncounterType(TableBase):
  92     """Rows in this table represent ways the player can enter a wild encounter;
  93     i.e. surfing, fishing, or walking through tall grass.
  94     """
  95
  96     __tablename__ = 'encounter_types'
  97     id = Column(Integer, primary_key=True, nullable=False)
  98     name = Column(Unicode(64), nullable=False)
  99
 100 class EncounterTypeSlot(TableBase):
 101     """Rows in this table represent an abstract "slot" within an encounter
 102     type, associated with both a condition group and a rarity.
 103
 104     Note that there are two encounters per slot, so the rarities will only add
 105     up to 50.
 106     """
 107
 108     __tablename__ = 'encounter_type_slots'
 109     id = Column(Integer, primary_key=True, nullable=False)
 110     encounter_type_id = Column(Integer, ForeignKey('encounter_types.id'), primary_key=False, nullable=False, autoincrement=False)
 111     encounter_condition_group_id = Column(Integer, ForeignKey('encounter_condition_groups.id'), primary_key=False, nullable=True, autoincrement=False)
 112     rarity = Column(Integer, nullable=False, autoincrement=False)
 113
 114 class EvolutionChain(TableBase):
 115     __tablename__ = 'evolution_chains'
 116     id = Column(Integer, primary_key=True, nullable=False)
 117     growth_rate_id = Column(Integer, ForeignKey('growth_rates.id'), nullable=False)
 118     steps_to_hatch = Column(Integer, nullable=False)
 119     baby_trigger_item = Column(Unicode(12))
 120
 121 class EvolutionMethod(TableBase):
 122     __tablename__ = 'evolution_methods'
 123     id = Column(Integer, primary_key=True, nullable=False)
 124     name = Column(Unicode(64), nullable=False)
 125     description = Column(Unicode(255), nullable=False)
 126
 127 class Generation(TableBase):
 128     __tablename__ = 'generations'
 129     id = Column(Integer, primary_key=True, nullable=False)
 130     name = Column(Unicode(16), nullable=False)
 131     main_region = Column(Unicode(16), nullable=False)
 132
 133 class GrowthRate(TableBase):
 134     """`formula` is written in LaTeX math notation."""
 135     __tablename__ = 'growth_rates'
 136     id = Column(Integer, primary_key=True, nullable=False)
 137     name = Column(Unicode(20), nullable=False)
 138     formula = Column(Unicode(500), nullable=False)
 139
 140 class Item(TableBase):
 141     __tablename__ = 'items'
 142     __singlename__ = 'item'
 143     id = Column(Integer, primary_key=True, nullable=False)
 144     name = Column(Unicode(16), nullable=False)
 145
 146 class Language(TableBase):
 147     __tablename__ = 'languages'
 148     id = Column(Integer, primary_key=True, nullable=False)
 149     name = Column(Unicode(16), nullable=False)
 150
 151 class Location(TableBase):
 152     __tablename__ = 'locations'
 153     __singlename__ = 'location'
 154     id = Column(Integer, primary_key=True, nullable=False)
 155     generation_id = Column(Integer, ForeignKey('generations.id'), nullable=False)
 156     name = Column(Unicode(64), nullable=False)
 157
 158 class LocationArea(TableBase):
 159     __tablename__ = 'location_areas'
 160     id = Column(Integer, primary_key=True, nullable=False)
 161     location_id = Column(Integer, ForeignKey('locations.id'), nullable=False)
 162     internal_id = Column(Integer, nullable=False)
 163     name = Column(Unicode(64), nullable=True)
 164
 165 class Machine(TableBase):
 166     __tablename__ = 'machines'
 167     machine_number = Column(Integer, primary_key=True, nullable=False, autoincrement=False)
 168     generation_id = Column(Integer, ForeignKey('generations.id'), primary_key=True, nullable=False, autoincrement=False)
 169     move_id = Column(Integer, ForeignKey('moves.id'), nullable=False)
 170
 171 class MoveDamageClass(TableBase):
 172     __tablename__ = 'move_damage_classes'
 173     id = Column(Integer, primary_key=True, nullable=False)
 174     name = Column(Unicode(8), nullable=False)
 175     description = Column(Unicode(64), nullable=False)
 176
 177 class MoveEffect(TableBase):
 178     __tablename__ = 'move_effects'
 179     id = Column(Integer, primary_key=True, nullable=False)
 180     priority = Column(SmallInteger, nullable=False)
 181     short_effect = Column(Unicode(256), nullable=False)
 182     effect = Column(Unicode(5120), nullable=False)
 183
 184 class MoveName(TableBase):
 185     __tablename__ = 'move_names'
 186     move_id = Column(Integer, ForeignKey('moves.id'), primary_key=True, nullable=False, autoincrement=False)
 187     language_id = Column(Integer, ForeignKey('languages.id'), primary_key=True, nullable=False, autoincrement=False)
 188     name = Column(Unicode(16), nullable=False)
 189
 190 class MoveTarget(TableBase):
 191     __tablename__ = 'move_targets'
 192     id = Column(Integer, primary_key=True, nullable=False)
 193     name = Column(Unicode(32), nullable=False)
 194     description = Column(Unicode(128), nullable=False)
 195
 196 class Move(TableBase):
 197     __tablename__ = 'moves'
 198     __singlename__ = 'move'
 199     id = Column(Integer, primary_key=True, nullable=False)
 200     name = Column(Unicode(12), nullable=False)
 201     generation_id = Column(Integer, ForeignKey('generations.id'), nullable=False)
 202     type_id = Column(Integer, ForeignKey('types.id'), nullable=False)
 203     power = Column(SmallInteger)
 204     pp = Column(SmallInteger, nullable=False)
 205     accuracy = Column(SmallInteger)
 206     target_id = Column(Integer, ForeignKey('move_targets.id'), nullable=False)
 207     damage_class_id = Column(Integer, ForeignKey('move_damage_classes.id'), nullable=False)
 208     effect_id = Column(Integer, ForeignKey('move_effects.id'), nullable=False)
 209     effect_chance = Column(Integer)
 210     contest_type = Column(Unicode(8), nullable=False)
 211     contest_effect_id = Column(Integer, ForeignKey('contest_effects.id'), nullable=True)
 212     super_contest_effect_id = Column(Integer, nullable=False)
 213
 214 class Pokemon(TableBase):
 215     """The core to this whole mess.
 216
 217     Note that I use both 'forme' and 'form' in both code and the database.  I
 218     only use 'forme' when specifically referring to Pokémon that have multiple
 219     distinct species as forms—i.e., different stats or movesets.  'Form' is a
 220     more general term referring to any variation within a species, including
 221     purely cosmetic forms like Unown.
 222     """
 223     __tablename__ = 'pokemon'
 224     __singlename__ = 'pokemon'
 225     id = Column(Integer, primary_key=True, nullable=False)
 226     name = Column(Unicode(20), nullable=False)
 227     forme_name = Column(Unicode(16))
 228     forme_base_pokemon_id = Column(Integer, ForeignKey('pokemon.id'))
 229     generation_id = Column(Integer, ForeignKey('generations.id'))
 230     evolution_chain_id = Column(Integer, ForeignKey('evolution_chains.id'))
 231     evolution_parent_pokemon_id = Column(Integer, ForeignKey('pokemon.id'))
 232     evolution_method_id = Column(Integer, ForeignKey('evolution_methods.id'))
 233     evolution_parameter = Column(Unicode(32))
 234     height = Column(Integer, nullable=False)
 235     weight = Column(Integer, nullable=False)
 236     species = Column(Unicode(16), nullable=False)
 237     color = Column(Unicode(6), nullable=False)
 238     pokemon_shape_id = Column(Integer, ForeignKey('pokemon_shapes.id'), nullable=False)
 239     habitat = Column(Unicode(16), nullable=False)
 240     gender_rate = Column(Integer, nullable=False)
 241     capture_rate = Column(Integer, nullable=False)
 242     base_experience = Column(Integer, nullable=False)
 243     base_happiness = Column(Integer, nullable=False)
 244     gen1_internal_id = Column(Integer)
 245     is_baby = Column(Boolean, nullable=False)
 246     has_gen4_fem_sprite = Column(Boolean, nullable=False)
 247     has_gen4_fem_back_sprite = Column(Boolean, nullable=False)
 248
 249     ### Stuff to handle alternate Pokémon forms
 250
 251     @property
 252     def national_id(self):
 253         """Returns the National Pokédex number for this Pokémon.  Use this
 254         instead of the id directly; alternate formes may make the id incorrect.
 255         """
 256
 257         if self.forme_base_pokemon_id:
 258             return self.forme_base_pokemon_id
 259         return self.id
 260
 261     @property
 262     def full_name(self):
 263         """Returns the name of this Pokémon, including its Forme, if any."""
 264
 265         if self.forme_name:
 266             return "%s %s" % (self.forme_name.capitalize(), self.name)
 267         return self.name
 268
 269     @property
 270     def normal_form(self):
 271         """Returns the normal form for this Pokémon; i.e., this will return
 272         regular Deoxys when called on any Deoxys form.
 273         """
 274
 275         if self.forme_base_pokemon:
 276             return self.forme_base_pokemon
 277
 278         return self
 279
 280 class PokemonAbility(TableBase):
 281     __tablename__ = 'pokemon_abilities'
 282     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 283     ability_id = Column(Integer, ForeignKey('abilities.id'), nullable=False)
 284     slot = Column(Integer, primary_key=True, nullable=False, autoincrement=False)
 285
 286 class PokemonDexNumber(TableBase):
 287     __tablename__ = 'pokemon_dex_numbers'
 288     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 289     generation_id = Column(Integer, ForeignKey('generations.id'), primary_key=True, nullable=False, autoincrement=False)
 290     pokedex_number = Column(Integer, nullable=False)
 291
 292 class PokemonEggGroup(TableBase):
 293     __tablename__ = 'pokemon_egg_groups'
 294     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 295     egg_group_id = Column(Integer, ForeignKey('egg_groups.id'), primary_key=True, nullable=False, autoincrement=False)
 296
 297 class PokemonFlavorText(TableBase):
 298     __tablename__ = 'pokemon_flavor_text'
 299     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 300     version_id = Column(Integer, ForeignKey('versions.id'), primary_key=True, nullable=False, autoincrement=False)
 301     flavor_text = Column(Unicode(255), nullable=False)
 302
 303 class PokemonFormGroup(TableBase):
 304     __tablename__ = 'pokemon_form_groups'
 305     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 306     description = Column(Unicode(512), nullable=False)
 307
 308 class PokemonFormSprite(TableBase):
 309     __tablename__ = 'pokemon_form_sprites'
 310     id = Column(Integer, primary_key=True, nullable=False)
 311     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 312     name = Column(Unicode(16), nullable=True)
 313
 314 class PokemonItem(TableBase):
 315     __tablename__ = 'pokemon_items'
 316     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 317     version_id = Column(Integer, ForeignKey('versions.id'), primary_key=True, nullable=False, autoincrement=False)
 318     item_id = Column(Integer, ForeignKey('items.id'), primary_key=True, nullable=False, autoincrement=False)
 319     rarity = Column(Integer, nullable=False)
 320
 321 class PokemonMove(TableBase):
 322     __tablename__ = 'pokemon_moves'
 323     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 324     version_group_id = Column(Integer, ForeignKey('version_groups.id'), primary_key=True, nullable=False, autoincrement=False)
 325     move_id = Column(Integer, ForeignKey('moves.id'), primary_key=True, nullable=False, autoincrement=False, index=True)
 326     pokemon_move_method_id = Column(Integer, ForeignKey('pokemon_move_methods.id'), primary_key=True, nullable=False, autoincrement=False)
 327     level = Column(Integer, primary_key=True, nullable=True, autoincrement=False)
 328     order = Column(Integer, nullable=True)
 329
 330 class PokemonMoveMethod(TableBase):
 331     __tablename__ = 'pokemon_move_methods'
 332     id = Column(Integer, primary_key=True, nullable=False, autoincrement=False)
 333     name = Column(Unicode(64), nullable=False)
 334     description = Column(Unicode(255), nullable=False)
 335
 336 class PokemonName(TableBase):
 337     __tablename__ = 'pokemon_names'
 338     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 339     language_id = Column(Integer, ForeignKey('languages.id'), primary_key=True, nullable=False, autoincrement=False)
 340     name = Column(Unicode(16), nullable=False)
 341
 342 class PokemonShape(TableBase):
 343     __tablename__ = 'pokemon_shapes'
 344     id = Column(Integer, primary_key=True, nullable=False)
 345     name = Column(Unicode(24), nullable=False)
 346     awesome_name = Column(Unicode(16), nullable=False)
 347
 348 class PokemonStat(TableBase):
 349     __tablename__ = 'pokemon_stats'
 350     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 351     stat_id = Column(Integer, ForeignKey('stats.id'), primary_key=True, nullable=False, autoincrement=False)
 352     base_stat = Column(Integer, nullable=False)
 353     effort = Column(Integer, nullable=False)
 354
 355 class PokemonType(TableBase):
 356     __tablename__ = 'pokemon_types'
 357     pokemon_id = Column(Integer, ForeignKey('pokemon.id'), primary_key=True, nullable=False, autoincrement=False)
 358     type_id = Column(Integer, ForeignKey('types.id'), nullable=False)
 359     slot = Column(Integer, primary_key=True, nullable=False, autoincrement=False)
 360
 361 class Stat(TableBase):
 362     __tablename__ = 'stats'
 363     id = Column(Integer, primary_key=True, nullable=False)
 364     name = Column(Unicode(16), nullable=False)
 365
 366 class TypeEfficacy(TableBase):
 367     __tablename__ = 'type_efficacy'
 368     damage_type_id = Column(Integer, ForeignKey('types.id'), primary_key=True, nullable=False, autoincrement=False)
 369     target_type_id = Column(Integer, ForeignKey('types.id'), primary_key=True, nullable=False, autoincrement=False)
 370     damage_factor = Column(Integer, nullable=False)
 371
 372 class Type(TableBase):
 373     __tablename__ = 'types'
 374     __singlename__ = 'type'
 375     id = Column(Integer, primary_key=True, nullable=False)
 376     name = Column(Unicode(8), nullable=False)
 377     abbreviation = Column(Unicode(3), nullable=False)
 378
 379 class VersionGroup(TableBase):
 380     __tablename__ = 'version_groups'
 381     id = Column(Integer, primary_key=True, nullable=False)
 382     generation_id = Column(Integer, ForeignKey('generations.id'), nullable=False)
 383
 384 class Version(TableBase):
 385     __tablename__ = 'versions'
 386     id = Column(Integer, primary_key=True, nullable=False)
 387     version_group_id = Column(Integer, ForeignKey('version_groups.id'), nullable=False)
 388     name = Column(Unicode(32), nullable=False)
 389
 390
 391 ### Relations down here, to avoid ordering problems
 392 Encounter.pokemon = relation(Pokemon, backref='encounters')
 393 Encounter.version = relation(Version, backref='encounters')
 394 Encounter.location_area = relation(LocationArea, backref='encounters')
 395 Encounter.slot = relation(EncounterTypeSlot, backref='encounters')
 396 Encounter.condition = relation(EncounterCondition, backref='encounters')
 397
 398 EncounterCondition.group = relation(EncounterConditionGroup,
 399                                     backref='conditions')
 400
 401 EncounterTypeSlot.type = relation(EncounterType, backref='slots')
 402
 403 EvolutionChain.growth_rate = relation(GrowthRate, backref='evolution_chains')
 404
 405 Generation.versions = relation(Version, secondary=VersionGroup.__table__)
 406
 407 LocationArea.location = relation(Location, backref='areas')
 408
 409 Machine.generation = relation(Generation)
 410
 411 Move.damage_class = relation(MoveDamageClass, backref='moves')
 412 Move.foreign_names = relation(MoveName, backref='pokemon')
 413 Move.generation = relation(Generation, backref='moves')
 414 Move.machines = relation(Machine, backref='move')
 415 Move.move_effect = relation(MoveEffect, backref='moves')
 416 Move.target = relation(MoveTarget, backref='moves')
 417 Move.type = relation(Type, backref='moves')
 418
 419 Move.effect = rst.MoveEffectProperty('effect')
 420 Move.priority = association_proxy('move_effect', 'priority')
 421 Move.short_effect = rst.MoveEffectProperty('short_effect')
 422
 423 MoveName.language = relation(Language)
 424
 425 Pokemon.abilities = relation(Ability, secondary=PokemonAbility.__table__,
 426                                       order_by=PokemonAbility.slot,
 427                                       backref='pokemon')
 428 Pokemon.formes = relation(Pokemon, primaryjoin=Pokemon.id==Pokemon.forme_base_pokemon_id,
 429                                                backref=backref('forme_base_pokemon',
 430                                                                remote_side=[Pokemon.id]))
 431 Pokemon.dex_numbers = relation(PokemonDexNumber, backref='pokemon')
 432 Pokemon.egg_groups = relation(EggGroup, secondary=PokemonEggGroup.__table__,
 433                                         order_by=PokemonEggGroup.egg_group_id,
 434                                         backref='pokemon')
 435 Pokemon.evolution_chain = relation(EvolutionChain, backref='pokemon')
 436 Pokemon.evolution_method = relation(EvolutionMethod)
 437 Pokemon.evolution_children = relation(Pokemon, primaryjoin=Pokemon.id==Pokemon.evolution_parent_pokemon_id,
 438                                                backref=backref('evolution_parent',
 439                                                                remote_side=[Pokemon.id]))
 440 Pokemon.flavor_text = relation(PokemonFlavorText, backref='pokemon')
 441 Pokemon.foreign_names = relation(PokemonName, backref='pokemon')
 442 Pokemon.items = relation(PokemonItem)
 443 Pokemon.generation = relation(Generation, backref='pokemon')
 444 Pokemon.shape = relation(PokemonShape, backref='pokemon')
 445 Pokemon.stats = relation(PokemonStat, backref='pokemon')
 446 Pokemon.types = relation(Type, secondary=PokemonType.__table__)
 447
 448 PokemonDexNumber.generation = relation(Generation)
 449
 450 PokemonFlavorText.version = relation(Version)
 451
 452 PokemonItem.item = relation(Item, backref='pokemon')
 453 PokemonItem.version = relation(Version)
 454
 455 PokemonFormGroup.pokemon = relation(Pokemon, backref=backref('form_group',
 456                                                              uselist=False))
 457 PokemonFormSprite.pokemon = relation(Pokemon, backref='form_sprites')
 458
 459 PokemonMove.pokemon = relation(Pokemon, backref='pokemon_moves')
 460 PokemonMove.version_group = relation(VersionGroup)
 461 PokemonMove.move = relation(Move, backref='pokemon_moves')
 462 PokemonMove.method = relation(PokemonMoveMethod)
 463
 464 PokemonName.language = relation(Language)
 465
 466 PokemonStat.stat = relation(Stat)
 467
 468 Type.damage_efficacies = relation(TypeEfficacy,
 469                                   primaryjoin=Type.id
 470                                       ==TypeEfficacy.damage_type_id,
 471                                   backref='damage_type')
 472 Type.target_efficacies = relation(TypeEfficacy,
 473                                   primaryjoin=Type.id
 474                                       ==TypeEfficacy.target_type_id,
 475                                   backref='target_type')
 476
 477 Version.version_group = relation(VersionGroup, backref='versions')
 478 Version.generation = association_proxy('version_group', 'generation')
 479
 480 VersionGroup.generation = relation(Generation, backref='version_groups')