Python3 sqlite3从json数据加载表

Question

背景故事

我有一台 Billion PowerTracker SG6200NXL，我的配电盘中有 3 个传感器。 直到最近，我写了一段 python 来从这个跟踪器下载一个 sqlite 数据库，这样我就可以绘制我的电源使用情况。 不幸的是，最近，USB 端口停止工作，而这正是 PowerTracker 存储 Sqlite 数据库的地方:( 更糟糕的是，PowerTracker 上传数据的网站已经关闭。 这两个事件使 PowerTracker 几乎毫无用处。 无奈之下，我可以使用 API 轮询和检索 JSON 格式的传感器数据。 我可以创建sqlite数据库和表，没有问题。 我可以轮询 PowerTracker，没问题。

我遇到的困难是将 JSON 数据加载到数据库表中。 该表包含列，其中许多未使用，但那些与名称中的 JSON 字段匹配。 所以，我收到一个包含 [version, cmd, status and devices] 的字典 设备条目是（设备）的列表。

每个设备都有一个字段字典，我想从中将数据值传输到数据库数据表中。

我可以循环并插入每个作为插入表 (column,column) 值 (dict[field], dict[field]) 但我认为必须有一种更 Pythony 的方式来执行此操作。

请参阅下面的一些调试输出，这可能会澄清这个问题。

   CREATE TABLE DATA (
      time_index     INTEGER,
      TimeStamp      INTEGER,
      EUI64          TEXT,
      modelident     TEXT,
      modelname      TEXT,
      alias          TEXT,      -- added this - check R script for compatability
      devicetype     INTEGER,
      voltage        REAL,
      current        REAL,
      frequency      REAL,
      powerfactory   REAL,
      activepower    REAL,
      apparentpower  REAL,
      mainenergy     REAL,
      voltage2       REAL,
      current2       REAL,
      frequency2     REAL,
      powerfactory2  REAL,
      activepower2   REAL,
      apparentpower2 REAL,
      mainenergy2    REAL,
      voltage3       REAL,
      current3       REAL,
      frequency3     REAL,
      powerfactory3  REAL,
      activepower3   REAL,
      apparentpower3 REAL,
      mainenergy3    REAL,
      voltage4       REAL,
      current4       REAL,
      frequency4     REAL,
      powerfactory4  REAL,
      activepower4   REAL,
      apparentpower4 REAL,
      mainenergy4    REAL,
      Dimming_L1     REAL,
      Dimming_L2     REAL,
      Dimming_L3     REAL,
      Dimming_L4     REAL,
      Temperature    REAL,
      Humidity       REAL,
      onoffstatus    INTEGER,
      rssi           INTEGER,
      lqi            INTEGER,
      nenergy        REAL,
      rssi1          INTEGER,
      CT_ratio       INTEGER
  );
  CREATE TABLE index_Table (
      num         INTEGER,
      HS_index    INTEGER,
      UpDateIndex INTEGER
  );

  Device ID               Usage
  000D6F0005A5D77E        Power Points
  000D6F0005A5BCAE        Shed
  000D6F0005A5BE9D        Grid


 So, the cmd=list_metering generates json output similar to the following

   {
       "devices": [
           {
               "signalstrength1": "N/A",
               "negativeenergy": "0.072",
               "mainenergy": "11282.062",
               "apparentpower": "805.22",
               "activepower": "698.76",
               "powerfactor": "87",
               "frequency": "50.02",
               "current": "3.38",
               "voltage": "238.43",
               "timestamp": "1609152925",
               "signalstrength": "40",
               "dimming": "false",
               "sense": "false",
               "supportIdentify": "1",
               "state": "N/A",
               "metering3phase": "false",
               "metering": "true",
               "alias": "Power Points",
               "modid": "gpm-hazr-4.2",
               "model": "SG3015-T3(100A)",
               "deviceid": "000D6F0005A5D77E"
           },
           {
               "signalstrength1": "N/A",
               "negativeenergy": "8272.385",
               "mainenergy": "11695.240",
               "apparentpower": "562.74",
               "activepower": "-32.76",
               "powerfactor": "-6",
               "frequency": "50.02",
               "current": "2.36",
               "voltage": "238.32",
               "timestamp": "1609152925",
               "signalstrength": "44",
               "dimming": "false",
               "sense": "false",
               "supportIdentify": "1",
               "state": "N/A",
               "metering3phase": "false",
               "metering": "true",
               "alias": "Grid",
               "modid": "gpm-hazr-4.2",
               "model": "SG3015-T3(100A)",
               "deviceid": "000D6F0005A5BE9D"
           },
           {
               "signalstrength1": "N/A",
               "negativeenergy": "50.763",
               "mainenergy": "11534.174",
               "apparentpower": "228.53",
               "activepower": "112.86",
               "powerfactor": "49",
               "frequency": "50.02",
               "current": "0.96",
               "voltage": "238.05",
               "timestamp": "1609152925",
               "signalstrength": "40",
               "dimming": "false",
               "sense": "false",
               "supportIdentify": "1",
               "state": "N/A",
               "metering3phase": "false",
               "metering": "true",
               "alias": "Shed",
               "modid": "gpm-hazr-4.2",
               "model": "SG3015-T3(100A)",
               "deviceid": "000D6F0005A5BCAE"
           }
       ],
       "status": "success",
       "cmd": "list_metering",
       "version": "1.1"
   }

Answer 1

我不是 python 专家，所以对改进 python3 编码风格的建议表示赞赏。

以下代码有效，不整洁，没有任何合理类型的错误处理，但它是概念证明。

    with requests.Session() as session:
        #print("Retrieving readings from Power Gateway...")
        cmd_list_metering_json_result = session.get("http://" + host + "/api_json.asp?cmd=list_metering&auth="+userPasswordBase64)
        #print("Retrieved.")
        cmd_list_metering_dict = cmd_list_metering_json_result.json()
        #print("Number of results: " , len(cmd_list_metering_dict))
        #print("cmd:list_metering:returned:", cmd_list_metering_dict)
        #print(json.dumps(cmd_list_metering_dict, indent=4, sort_keys=True))

        #print("All keys ", cmd_list_metering_dict.keys())

        if cmd_list_metering_dict['status'] != 'success':
            syslog.syslog("FAILURE to retrieve cmd_list_metering from power gateway")
            exit(1)
        #
        ## Only interested in the 'devices' key
        ## which is a list of dictionaries, one dictionary per device
        ## 
        #
        #print("All Devices = ",  cmd_list_metering_dict['devices'])
        #print("Type = ", type( cmd_list_metering_dict['devices']) )

        numberOfDevices = len(cmd_list_metering_dict['devices'])
        #print("Number of devices = ", numberOfDevices)
        if numberOfDevices != 3:
            syslog.syslog("PowerTracker requires reboot - expect 3 devices")
            exit(1)
                    
        devIx = 0
        timeOfDayInSeconds = int(datetime.datetime.today().timestamp())
        #print("timeOfDayInSeconds = ", timeOfDayInSeconds)
        for devIx in range(0, numberOfDevices):
            device_dict = cmd_list_metering_dict['devices'][devIx]
            #print("Storing device ", device_dict['deviceid'], " alias ", device_dict['alias'])
            data_tuple = (
                           timeOfDayInSeconds   
                          ,device_dict['timestamp']
                          ,device_dict['deviceid']
                          ,device_dict['modid']
                          ,device_dict['model']
                          ,device_dict['alias']
                          ,15                    
                          ,device_dict['voltage']
                          ,device_dict['current']
                          ,device_dict['frequency']
                          ,device_dict['powerfactor']
                          ,device_dict['activepower']
                          ,device_dict['apparentpower']
                          ,device_dict['mainenergy']
                          ,1
                          ,device_dict['signalstrength']
                          ,1
                          ,device_dict['negativeenergy']
                          ,1
                          )
            
            rowsInserted = dbCursor.execute("""insert into DATA (
   time_index
  ,TimeStamp      
  ,EUI64          
  ,modelident     
  ,modelname      
  ,alias          
  ,devicetype     
  ,voltage        
  ,current        
  ,frequency      
  ,powerfactory   
  ,activepower    
  ,apparentpower  
  ,mainenergy     
  ,onoffstatus    
  ,rssi
  ,lqi           
  ,nenergy        
  ,CT_ratio
) values (
   ?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
  ,?
    );""", data_tuple)

    #print("Committing transaction...")
    dbConn.commit()
    #print("Closing cursor...")
    dbCursor.close()            
    #if dbConn:
    #    print("Disconnecting from database...")
    #    dbConn.close()