I have :
class Award(models.Model) :
name = models.CharField(max_length=100, db_index=True)
class Alias(models.Model) :
awards = models.ManyToManyField('Award', through='Achiever')
class Achiever(models.Model):
award = models.ForeignKey(Award)
alias = models.ForeignKey(Alias)
count = models.IntegerField(default=1)
How can I have an Alias
which has all its achiever_set
and awards
prepopulated?
>>> db.reset_queries()
>>> Alias.objects.filter(id="450867").select_related("achiever_set__award").get().achiever_set.all()[0].award.name
u'Perma-Peddle'
>>> len(db.connection.queries)
3
>>> db.reset_queries()
>>> Alias.objects.filter(id="450867").select_related("awards").get().awards.all()[0].name
u'Dwarfageddon (10 player)'
>>> len(db.connection.queries)
2
I'm going to need a lot of access to the award that an alias has already gotten (both the intermediate table and the awards themselves). How can I batch all of these?
Django versions 1.4 and above have prefetch_related
for this purpose.
The prefetch_related
method is similar to select_related
, but does not do a database join. Instead, it executes additional database queries and does the joining in Python.