select_related

[Sergey Tikhonov]

I.e., we have City-Country-Continent db schema. I need to obtain continents for some cities. To do this, now I have these options:

• query City with depth=2
• write custom serializer class on server side

depth is not a bad option, but if you need more than one join, all these relations may become a problem.

So, the proposal is to add "select_related" option to filter() arguments.

• it adds qs.select_related(*fields) to serializers queryset
• it automatically created fields, named like select_related values

For example:

>>> client.filter('City', kwargs={
  'filters': {},
  'select_related': ['country__continent']
})

[{
  'id': 1,
  'name': 'Moscow',
  'country__continent': 'Eurasia'
}]

Problems found:

• Django select_related() adds related objects as obj.country.continent
• Thus, you need to write complex serializer method to obtain continent serialized data
• if you setattr this method to GenericSerializerClass object, it doesn't become 'bound method', so some __new__ magic is needed
• also, ModelSerializer need to be constructed for Continent model, and model class must be resolved before instantiation of GenericSerializerClass

Lot's of stuff to think about.

[Alexey Manaev]

Thanks!