Varios M2M en django

Question

Tengo dos modelos en Django para un mapa 2d basado en el juego:

class Block(models.Model):
   type = models.IntegerField()

class ShopBuilding(models.Model):
   house_blocks = models.ManyToManyField(Block)
   street_blocks = models.ManyToManyField(Block)
   river_blocks = models.ManyToManyField(Block)
   decoration_blocks = models.ManyToManyField(Block)
   npc_blocks = models.ManyToManyField(Block)

Ahora sólo quiero asociar estos dos modelos utilizando UNA tabla:

class ShopBlockAssoc(models.Model):
    block = models.ForeignKey(Block)
    shop = models.foreignKey(Shop)

Tras configurar la through campo en ShopBuilding modelo de Django yiled múltiples falla cuando syncdb, como

    Error: One or more models did not validate:
tnew.shopbuilding: Accessor for m2m field 'house_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'house_blocks'.
tnew.shopbuilding: Accessor for m2m field 'house_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'house_blocks'.
tnew.shopbuilding: Accessor for m2m field 'house_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'house_blocks'.
tnew.shopbuilding: Accessor for m2m field 'house_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'house_blocks'.
tnew.shopbuilding: Accessor for m2m field 'street_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'street_blocks'.
tnew.shopbuilding: Accessor for m2m field 'street_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'street_blocks'.
tnew.shopbuilding: Accessor for m2m field 'street_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'street_blocks'.
tnew.shopbuilding: Accessor for m2m field 'street_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'street_blocks'.
tnew.shopbuilding: Accessor for m2m field 'river_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'river_blocks'.
tnew.shopbuilding: Accessor for m2m field 'river_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'river_blocks'.
tnew.shopbuilding: Accessor for m2m field 'river_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'river_blocks'.
tnew.shopbuilding: Accessor for m2m field 'river_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'river_blocks'.
tnew.shopbuilding: Accessor for m2m field 'decoration_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'decoration_blocks'.
tnew.shopbuilding: Accessor for m2m field 'decoration_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'decoration_blocks'.
tnew.shopbuilding: Accessor for m2m field 'decoration_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'decoration_blocks'.
tnew.shopbuilding: Accessor for m2m field 'decoration_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'decoration_blocks'.
tnew.shopbuilding: Accessor for m2m field 'npc_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'npc_blocks'.
tnew.shopbuilding: Accessor for m2m field 'npc_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'npc_blocks'.
tnew.shopbuilding: Accessor for m2m field 'npc_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'npc_blocks'.
tnew.shopbuilding: Accessor for m2m field 'npc_blocks' clashes with related m2m field 'Block.shopbuilding_set'. Add a related_name argument to the definition for 'npc_blocks'.

Si he de poner db_table campo de Django dice:

The model has two manually-defined m2m relations through the model, which is not permitted. Please consider using an extra field on your intermediary model instead.

Cómo podría solucionar este problema?Realmente quiero asegurarme de que la tienda de bloque de las relaciones mediante el intercambio de la misma intermedio asociado modelo con el mismo db_table

Answer 1

El problema es que en el modelo Block intenta crear enlaces hacia atrás.Django nombres de los vínculos basados en el Modelo, en su caso, para todos los ManyToMany intenta crear shopbuilding_set y los nombres de colisión.Para evitar este complemento related_name, por ejemplo:

class ShopBuilding(models.Model):
   house_blocks = models.ManyToManyField(Block, related_name="shopbuilding_house_set")
   street_blocks = models.ManyToManyField(Block, related_name="shopbuilding_street_set")
   river_blocks = models.ManyToManyField(Block, related_name="shopbuilding_river_set")
   decoration_blocks = models.ManyToManyField(Block, related_name="shopbuilding_decoration_set")
   npc_blocks = models.ManyToManyField(Block, related_name="shopbuilding_npc_set")

Entonces usted será capaz de acceder a ShopBuilding de Block ejemplo como este:

block.shopbuilding_npc_set.all()