Question

我一直试图找到一种使用xively-python库从通道中正确读取数据的方法。我尝试检索current_value但它似乎只检索初始值，即使在Xively界面中更改通道中的值之后也是如此。例如，频道＆＃39;命令中的初始值＆＃39;是＆＃34;退出＆＃34;。这是我的程序正确检索和执行的。但是，如果我结束该程序，请更新＆＃39;命令＆＃39;渠道价值为＆＃39; AA＆＃39;然后重启我的程序，它仍然选择退出＆＃39;退出。我已经测试了10-15分钟，确保超过20秒，以确保正确更新。

看看API，我似乎无法找到一种方法。我想要做的是检索给定频道的最新值。我使用频道作为在未连接设备之间传递命令的方法。我希望定期阅读该频道。

一个小小的说明，我看到一年前发布的类似问题，但没有得到答复。

编辑：我似乎只是根据Xively HTTP请求提要在程序开头读取一次current_value，我使用的代码是：

#!/usr/bin/env python
# -*- coding: utf-8 -*-

#import serial library and sleep from the time library
import serial
from time import sleep
import xively
import requests
from datetime import datetime

#declare port and baud rate then open conn
port = '/dev/ttyAMA0'
baud = 9600
ser = serial.Serial(port=port, baudrate = baud)

#xively variables
FEED_ID = "1032676103"
API_KEY = "FZ2IOZkDW5ZXAITh6kqqUVkZEIBfNk6y2SKxgx4DDDVLxi46"

#xively connection function reutrning a datastream handle
def open_connection(feed,target):
    try:
        datastream = feed.datastreams.get(target)
        print("Channel " + target + " found!")
        return datastream
    except:
        datastream = feed.datastreams.create(target)
        print("Channel " + target + " not found,new channel created!")
        return datastream

#push function
def push(target,value):
    target.current_value = value
    target.at = datetime.utcnow()
    try:
        target.update()
    except requests.HTTPError as e:
        print "HTTPError({0}): {1}".format(e.errno,e.strerror)

#pop function
def pull():
    command = open_connection(feed,"Command")
    command.at = datetime.utcnow()
    sleep(0.2)
    #return target.get(datetime.utcnow())
    return command.current_value


#check status of board 1 relay A
def status_one():
    ser.write('aAARELAYA---')
    sleep(0.2)
    reply = ser.read(12)
    sleep(0.2)
    relayAA = reply[9:]
    relayAA = relayAA.strip('-')
    return relayAA   

#check status of board 2 relay A
def status_two():
    ser.write('aBBRELAYA---')
    sleep(0.2)
    reply = ser.read(12)
    relayBA = reply[9:]
    relayBA = relayBA.strip('-')
    return relayBA

#toggle boardAA relay A function
def toggle_aa():
    ser.write('aAARELAYATOG')
    sleep(0.2)
    reply = ser.read(12)
    print(reply)
    sleep(0.2)

#toggle boardBB relay A function
def toggle_bb():
    ser.write('aBBRELAYATOG')
    sleep(0.2)
    reply = ser.read(12)
    print(reply)
    sleep(0.2)    

#setup and initial push to Xively

ser.flushInput()

api = xively.XivelyAPIClient(API_KEY)
feed = api.feeds.get(FEED_ID)
oneastatus = open_connection(feed,"Relay_1A")
twoastatus = open_connection(feed,"Relay_2A")
hubstatus = open_connection(feed,"Relay_Data")
#command = open_connection(feed,"Command")
hub = 1
push(hubstatus,hub)

relayAA = status_one()
print(relayAA)
push(oneastatus,relayAA)
relayBA = status_two()
print(relayBA)
push(twoastatus,relayBA)


#loop section - command handling
while hub:

    #operator = pull(command)
    operator = pull()
    sleep(0.2)
    print(operator)

    #command to toggle AA
    if operator == 'AA':
        toggle_aa()
        sleep(0.2)
        relayAA = status_one()
        push(oneastatus,relayAA)
        sleep(0.2)

    #command to toggle BA
    if operator == 'BA':
        toggle_bb()
        sleep(0.2)
        relayBA = status_two()
        push(twoastatus,relayBA)
        sleep(0.2)

    #command to shutdown
    if operator == 'Exit':
        hub = 0


#close conn
push(hubstatus,hub) 
ser.close

正如您所看到的，我最初尝试创建＆＃39;命令＆＃39;变量连接一次，然后尝试在循环内创建它，看它是否改变了东西。我需要它像数据更新一样频繁地读取通道的current_value，或者至少在半定期的基础上读取通道的current_value以允许发送和实现命令。

Answer 1

我在REPL中尝试了这个，但看不出你出现问题的原因。

[xively-python] 0 %> python
requPython 2.7.5 (default, Aug 25 2013, 00:04:04) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.0.68)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import xively
>>> FEED_ID = "1032676103"
>>> API_KEY = "FZ2IOZkDW5ZXAITh6kqqUVkZEIBfNk6y2SKxgx4DDDVLxi46"
>>> api = xively.XivelyAPIClient(API_KEY)
>>> f = api.feeds.get(FEED_ID)
>>> d = f.datastreams.get('Command')
>>> print(d.current_value)
Exit

然后我将Xively工作台上的值修改为Exit2并且它有效：

>>> d = f.datastreams.get('Command')
>>> print(d.current_value)
Exit2

我现在将值翻转回Exit，这看起来也很好：

>>> d = f.datastreams.get('Command')
>>> print(d.current_value)
Exit

使用python从xively通道读取最新值

1 个答案: