Python-如何从Firebase获取和使用数据？

Question

Here is my updated code with the revisions. I only added the user_num = 1 to try to avoid the unsupported operand error I was getting , but that didn't work either.

class MetropolisApp(App):
    user_num = 1
    database_url = 'https://metropolis-58211.firebaseio.com/'

    def build(self):
        self.my_firebase = MyFirebase()
        return ControlScreens()

    def on_start(self):
        user_num_req = requests.get("https://metropolis-58211.firebaseio.com/user_num.json")
        self.user_num = user_num_req.json()

        db = requests.get('https://metropolis-58211.firebaseio.com/' + str(self.user_num) + '.json')
        #print(db.ok)
        data = json.loads(db.content.decode())
        #print(data)


    def post(self, firstname, lastname, email, username, password):

        self.user_num += 1

        # Make a python dictionary
        fname_data = {"fname": firstname}
        lname_data = {"lname": lastname}
        email_data = {"email": email}
        user_id = {"userid": username}
        user_pw = {"userpw": password}

        # Send the python dictionary
        requests.post(url=self.database_url + str(self.user_num) + '.json', json=fname_data)
        requests.post(url=self.database_url + str(self.user_num) + '.json', json=lname_data)
        requests.post(url=self.database_url + str(self.user_num) + '.json', json=email_data)
        requests.post(url=self.database_url + str(self.user_num) + '.json', json=user_id)
        requests.post(url=self.database_url + str(self.user_num) + '.json', json=user_pw)

    def in_database(self, firstname, lastname, email, username, password):

        fname_data = {"fname": firstname}
        lname_data = {"lname": lastname}
        email_data = {"email": email}
        user_id = {"userid": username}
        user_pw = {"userpw": password}

        requests.patch(url=self.database_url + str(self.user_num) + '.json', json=fname_data)
        requests.patch(url=self.database_url + str(self.user_num) + '.json', json=lname_data)
        requests.patch(url=self.database_url + str(self.user_num) + '.json', json=email_data)
        requests.patch(url=self.database_url + str(self.user_num) + '.json', json=user_id)
        requests.patch(url=self.database_url + str(self.user_num) + '.json', json=user_pw)

        check_request = requests.get(
            'https://metropolis-58211.firebaseio.com/.json?orderBy="userid"&equalTo="%s"' % self.root.ids[
                'user_login'].text)
        print(check_request.json())

        # print(self.root.ids)

Not sure if the .kv file is needed, but here is the main code in which I am having errors.

Edited Database

Answer 1

There are a couple concepts to understand here. The first is the rule system of Firebase's real-time database. The rule system dictates what kind of reads/writes to the database are allowed. An important part of the rule system is using indexes to tell Firebase that you want to be able to query your data by a certain parameter. For example, you need to query your database by the userid parameter. In your rules tab of your real-time database, you need to tell Firebase to let you 'indexOn' the 'userid' parameter, like so:

{
  "rules": {
    ".read": true, // Note - this allows all reads from anyone anywhere. only use for testing
    ".write": true, // same comment
    ".indexOn": ["userid"] // You can allow multiple indexOns by doing ["userid","foo","bar"]
  }
}

The ".indexOn" portion above is part of your top level rules ( / in your database), and you want to index on data that is inside some special identifier ( /special_identifier/userid ). The special identifier for your test user is 2 in this case.

Now that you are allowing your database to be queried by the userid parameter, you need to actually send a request using python to query it. The next concept here is sending some special arguments in the URL of your get request (read Firebase's documentation here ). In this case, you need to try to get data from your top level ( / ) location, and orderBy userid and only return values equalTo self.root.ids['user_login'].text

Your URL in this case would be:

'https://metropolis-58211.firebaseio.com/.json?orderBy="userid"&equalTo="%s"'%self.root.ids['user_login'].text

Notice how you use the ? character to specify you're going to send some special parameters, and the & means another special parameter is coming. Also make sure your values that you are ordering-by or equaling-to are surrounded in " (assuming their strings in your database, which they are at the moment).

When you do a get request to that URL, either it will return the data for that user, or an empty dictionary.

check_request = requests.get('https://metropolis-58211.firebaseio.com/.json?orderBy="userid"&equalTo="%s"'%self.root.ids['user_login'].text)
print(check_request.json()) # If this has data, the user exists, if it's an empty dictionary, {}, the user doesn't exist