python-firebase添加时获取项目

Question

So I am working with python-firebase at the moment, and I have been working with JavaScript and Firebase before. In JS there was the ref.on('child_added') , but I am looking to do the same with python-firebase (I have to check firebase each time a node is added, so I assume I would need something like this).

So how exactly can I do this?

Answer 1

Using Firebase's REST API (which is what their python API is under the hood), you save the elements using a POST request, which returns the ids of the added elements, so persist that somewhere. Retrieve your elements and iterate through them for the relevant id:

# assume your instance is called phones and your username is jack, change as appropriate
def get_object(newest_id):
    objects = requests.get('https://samplechat.firebaseio-demo.com/users/jack/phones.json').json()
    added_object = [obj for obj in objects if obj == newest_id][0]
    return added_object

def add_object(dictionary_representing_object):
    newest_id = requests.post('https://samplechat.firebaseio-demo.com/users/jack/phones.json', json=json.dumps(dictionary_representing_object), verify=False).json()['name']
    stored_object = get_object(newest_id) # stored_object will be a superset of what's in dictionary_representing_object -- it will have an additional entry representing firebase's unique id

Hope that helps.

Answer 2

@hd1's answer works and uses the python-firebase library you already use. But as you say, it will indeed have to poll for updates.

An alternative would be to listen for Firebase's REST streaming API . There is a Python example of how to consume the REST events (using the Python request and sseclient libraries). The read loop is here :

        self.sse = ClosableSSEClient(URL)
        for msg in self.sse:
            msg_data = json.loads(msg.data)
            if msg_data is None:    # keep-alives
                continue
            path = msg_data['path']
            data = msg_data['data']
            if path == '/':
                # initial update
                if data:
                    keys = data.keys()
                    keys.sort()
                    for k in keys:
                        self.message_queue.put(data[k])
            else:
                # must be a push ID
                self.message_queue.put(data)

While it is not as simple as the native JavaScript client that you've used before, it's as close as you can get to that functionality in Python.