python之如何用 python 检测 firebase child 的变化

我在使用这个应用程序时遇到了一些问题。我需要的是，如果我检测到数据库 (FIREBASE) 发生变化，特别是在“sala”和“ventilacion”节点中，该函数将执行它必须执行的操作。如果数据库中没有任何变化，它就什么都不做。我正在使用 python 和 pyrebase 库。这是代码。非常感谢您的帮助。

import pyrebase 
import serial 
import time 
config = { 
    #firebase configurations 
} 
 
firebase = pyrebase.initialize_app(config) 
 
db = firebase.database() 
def ReconfiguracionFabrica(): 
    ser.write('AT') 
    time.sleep(0.2) 
    ser.write('AT+RENEW') 
    time.sleep(0.3) 
 
def ConfiguracionMaster(): 
    time.sleep(0.5) 
    ser.write('AT+IMME1') 
    time.sleep(0.350) 
    ser.write('AT+ROLE1') 
    time.sleep(0.2)      
 
ser = serial.Serial(port="/dev/ttyAMA0", baudrate=9600, timeout=1) 
ReconfiguracionFabrica() 
time.sleep(0.1) 
ConfiguracionMaster() 
time.sleep(0.1) 
 
print "**********   INICIO  *************" 
 
ser.flushInput() 
contador = 0 
prender = '' 
ventilacion1 = '' 
checkeo = '' 
 
while True: 
    #if db.child("sala").: # It is the line where would be the conditional that allows me to detect any change only in the sala's node. 
        salidaLed1 = db.child("sala").get() 
        ser.write('AT') 
        time.sleep(0.1) 
        ser.write('AT+CON508CB16A7014') 
        time.sleep(0.1) 
        if salidaLed1.val() == True: 
            prender = ";" 
        if salidaLed1.val() == False: 
            prender = "," 
 
        ser.write('luz: %s \n' %(prender)) 
        print ('luz: %s \n' %(prender)) 
        time.sleep(1) 
        ser.read(checkeo) 
        if checkeo == 'j': 
            ReconfiguracionFabrica() 
            time.sleep(0.1) 
            ConfiguracionMaster() 

请您参考如下方法:

Question: How to detect changes in firebase child

Note: All Examples use Public Access

1. 设置示例数据并验证其可读性。
   此操作必须一次!

   temperature_c = 30 
   data = {'date':time.strftime('%Y-%m-%d'),  
           'time':time.strftime('%H:%M:%S'),  
           'temperature':temperature_c} 
   db.child('public').child('Device_1').set(data) 
    
   response = db.child('public').child('Device_1').get() 
   print(response.val()) 
   

2. 创建第一个执行更新的脚本:

   for t in [25, 26, 27, 28, 29, 30, 31, 32, 33, 35]: 
       temperature_c = t 
       data = {'date':time.strftime('%Y-%m-%d'),  
               'time':time.strftime('%H:%M:%S'),  
               'temperature':temperature_c} 
       db.child('public').child('Device_1').update(data) 
       time.sleep(60) 
   

3. 使用流处理程序创建第二个脚本

   def stream_handler(message): 
       print('event={m[event]}; path={m[path]}; data={m[data]}' 
           .format(m=message)) 
    
   my_stream =db.child('public').child('Device_1').stream(stream_handler) 
    
   # Run Stream Handler forever 
   while True: 
       data = input("[{}] Type exit to disconnect: ".format('?')) 
       if data.strip().lower() == 'exit': 
           print('Stop Stream Handler') 
           if my_stream: my_stream.close() 
           break 
   

4. 运行流处理器脚本:

   启动后 def stream_handler 的响应输出(初始数据):

   event="put"; path=/;  data={'Device_1': {'temperature': 30, 'time': '13:34:24', 'date': '2017-07-20'}} 
   

5. 运行更新程序脚本:

6. 观察流处理器脚本的输出

   def stream_handler 在第一次 更新数据后的响应输出:

   event=patch; path=/Device_1;  data={'temperature': 25, 'time': '13:49:12'} 
   

使用 Python 测试:3.4.2

Pyrebase
streaming

You can listen to live changes to your data with the stream() method.

def stream_handler(message): 
    print(message["event"]) # put 
    print(message["path"]) # /-K7yGTTEp7O549EzTYtI 
    print(message["data"]) # {'title': 'Pyrebase', "body": "etc..."} 
 
my_stream = db.child("posts").stream(stream_handler) 

You should at least handle put and patch events. Refer to "Streaming from the REST API" for details.