onSnapshot() Firestore 使用 Flask-Sockets 多次发送更改

Question

我正在尝试与Flask和Firestore进行网络聊天。我设置了一个流程来接收来自 firestore 的新消息(当数据库中发生更改时(并通过 websocket 发送到 UI。像这样：

蟒：

@sockets.route('/messages')
def chat_socket(ws):
message = None
def callback_snapshot(col_snapshot, changes, read_time):
with app.app_context():
Messages = []
for change in changes:
if change.type.name == 'ADDED':
Messages.append(change.document)
conversation = render_template(
'conversation.html',
Messages = Messages,
)
numberID = None
if len(col_snapshot) > 0:
for i in col_snapshot:
a = i 
numberID = a.reference.parent.parent.id
response = json.dumps({
'conversation': conversation,
'numberID': numberID
})
ws.send(response)
while not ws.closed:
response = json.loads(ws.receive())
newNumberID = response['newNumberID'].strip()
query_snapshot = fn.GetMessages(newNumberID)
doc_watch = query_snapshot.on_snapshot(callback_snapshot)
if message is None:
continue

Javascript：

function messages(numberID) {
var scheme = window.location.protocol == "https:" ? 'wss://' : 'ws://';
var webSocketUri =  scheme
+ window.location.hostname
+ (location.port ? ':'+location.port: '')
+ '/messages';
/* Get elements from the page */
var form = $('#chat-form');
var textarea = $('#chat-text');
var output = $('.messages');
var status = $('.messages');
var websocket = new WebSocket(webSocketUri);
websocket.onopen = function() {};
websocket.onclose = function() {};
websocket.onmessage = function(e) {    
numberID = JSON.parse(e.data).numberID
conversation = JSON.parse(e.data).conversation
output.append(conversation);   
if (numberID == null){
output.empty();
}};
websocket.onerror = function(e) {console.log(e);};
websocket.onopen = () => websocket.send(numberID);
};

问题是：当我使用 col_snapshot 作为消息时，除了每次发送消息时都会将整个 firestore 集合发送给用户之外，一切都很好。所以这完全没有效率。如上所述，当我仅为更改设置回调时，如果我多次触发该函数，不知何故我为同一集合设置了多个侦听器，因此我在 UI 中获得了多个"更改更新"。如何跟踪这些侦听器，以便每个集合仅设置一个侦听器？

Answer 1

从文档中可以看出，每个文档只应调用GetMessages和on_snapshot一次。

@sockets.route('/messages')
def chat_socket(ws):
message = None
def callback_snapshot(col_snapshot, changes, read_time):
with app.app_context():
# Rest of the function ...
ws.send(response)
response = json.loads(ws.receive())
numberID = response['newNumberID'].strip()
query_snapshot = fn.GetMessages(numberID)
doc_watch = query_snapshot.on_snapshot(callback_snapshot)
while not ws.closed:
newNumberID = response['newNumberID'].strip()
response = json.loads(ws.receive())
if newNumberID != numberID:
numberID = newNumberID
query_snapshot = fn.GetMessages(numberID)
doc_watch = query_snapshot.on_snapshot(callback_snapshot)