How can i send message to channel in views?

[麦田的守望者]

I want upload an excel file to server by FileField, and then the server read data from the excel and update the database in a view.

the problem is that the database updating  may sustain a long time, i want  send the progress to the browser. i think django channel may be a good choice, but i don't know how to send message from a view to a channel?