freakypie/django-binding

Django Binding

Provides server a real time cache for querysets.

A binding will keep a cached queryset and registers Django signals to update the cache as the models change.

Naturally changes that don't trigger a Django post_save or post_delete will not cause the cache to be updated.

Also providing binding implementations for:

• DRF
• django-node-websockets
• django channels

Getting started

create a binding:

from binding import Binding

# bind all active users
class UserBinding(Binding):
    filters = dict(active=True)

users = UserBinding()
users.all()  # will get a cache of the currently active users

Django Rest Framework

create a BoundModelViewset and it will automatically cache the queryset and keep it up to date. When Etags/last modified are supported it will return 304 responses for you automatically:

class ProductSerializer(Serializer):
    model = Product

class BoundProductViewset(BoundModelViewSet):
    model = Product
    serializer_class = ProductSerializer

You can also specify a custom binding on the ViewSet:

class ProductBinding(Binding):
    model = Product

    def filters(self):
        return {"active": true}      

class BoundProductViewset(BoundModelViewSet):
    binding = ProductBinding
    serializer_class = ProductSerializer

Django Node Websockets

With websockets you can get instant notification of changes to the queryset.

class ProductBinding(Binding):
    model = Product

class ProductWebsocketView(BoundWebsocketView):
    event = "products"
    binding = ProductBinding()
    groups = ["products"]  # specify which group to update

Then hook it up to the event of your choice:

urlpatterns = patterns(
    '',
    url(r'^products', ProductWebsocketView.as_view()),
)

From the javascript side emit the choosen event to connect, emit it again with {disconnect: true} to disconnect.

Listen for the same even to get updates

// listen for updates
io.on("products", (data) => {
  // data.action: create, update, delete, sync
  //              sync means that it is giving you the full queryset
  // data.payload: the related data
});

// connect and sync
io.emit("products")

// disconnect
io.emit("products", {disconnect: true})