Difference in the receive and send method in a websocket - python-3.x

Question

I am looking over the following code which does a 'group chat' with different members:
# Receive message from WebSocket
def receive(self, text_data):
text_data_json = json.loads(text_data)
message = text_data_json['message']
# Send message to room group
async_to_sync(self.channel_layer.group_send)(
self.room_group_name,
{
'type': 'chat_message',
'message': 'OK'
}
)
# Receive message from room group
def chat_message(self, event):
message = event['message']
# Send message to WebSocket
self.send(text_data=json.dumps({
'message': message
}))
My questions is what do the two items do? I see that receive(), also does the group_send, so what purpose does the chat_message have if the receive sends it upon receiving it?

Answer 1

That chat server code is a simple example on how to send group messages.
In the code:
async_to_sync(self.channel_layer.group_send)(
self.room_group_name,
{
'type': 'chat_message',
'message': 'OK'
}
)
this line
'type': 'chat_message',
is responsible for calling method chat_message() with { 'message': 'OK'}
Before sending this message to the group members you may want to modify or check the data, or need to do other stuff. That's why self.channel_layer.group_send doesn't directly sends message to the group but calls another method (in this case chat_message) to handle sending of message and to keep receive() method's code clean.