使用 Python SSHTunnelForwarder 时出现“NoneType”错误答案

【问题标题】：'NoneType' error using Python SSHTunnelForwarder使用 Python SSHTunnelForwarder 时出现“NoneType”错误
【发布时间】：2020-09-04 16:11:24
【问题描述】：

我正在尝试编写一个将按计划运行的脚本，以更新位于云上的数据库。我使用 SSHTunnelForwarding 与我的数据库建立连接。它全部打包在一个函数中，因此我所要做的就是在函数中传递查询字符串并运行它。这个函数在 CSV 中循环了大约 1000 行数据。每行都被更改为正确的格式，并且正在创建一个 sql 表达式。

with open (CSV, 'r') as f:
    reader = csv.reader(f)
    data = next(reader)
    #load new data
    for newrow in reader:
        row = []
        for val in newrow:
            try:
                val = float(val)
            except:
                val = "'"+val.strip()+"'"
            row.append(val)

        id = row[0]
        phase_order = row[1]
        Ajera_Project_Key = row[2]
        project_id = row[3]
        Project_Description = row[4]
        Ajera_Client_Key = row[5]
        Client = row[6]
        Ajera_PM_Key = row[7]
        Project_Manager = row[8]
        Ajera_PIC_Key = row[9]
        Principal_In_Charge = row[10]
        title = row[11]
        Ajera_Dept_Key = row[12]
        Project_Status = row[13]
        Phase_Status = row[14]
        Department = row[15]
        Project_Type = row[16]
        start = row[17]
        end = row[18]
        hours_budgeted = row[19]
        Hours_Worked = row[20]
        Hours_Remaining = row[21]
        Total_Contract_Amount = row[22]
        Billed = row[23]
        Billed_Labor = row[24]
        Billed_Hours = row[25]
        WIP = row[26]
        Spent = row[27]
        Spent_Labor = row[28]
        FTEs = row[29]

        q = 'INSERT INTO project_phases_test VALUES ({0},{1},{2},{3},{4},{5},{6},{7},{8},{9},{10},{11},{12},{13},{14},{15},{16},{17},{18},{19},{20},{21},{22},{23},{24},{25},{26},{27},{28},{29});'.format(id,phase_order,Ajera_Project_Key,project_id,Project_Description,Ajera_Client_Key,Client,Ajera_PM_Key,Project_Manager,Ajera_PIC_Key,Principal_In_Charge,title,Ajera_Dept_Key,Project_Status,Phase_Status,Department,Project_Type,start,end,hours_budgeted,Hours_Worked,Hours_Remaining,Total_Contract_Amount,Billed,Billed_Labor,Billed_Hours,WIP,Spent,Spent_Labor,FTEs)

        print (q)

        query(q)

我遇到的问题是当我尝试输入除简单选择之外的查询字符串时。我传递给它的每个插入、更新、删除语句，我都会收到一个错误，指出“NoneType”对象不可迭代。然而，正如我之前提到的，如果我通过一个 select 语句，我会得到我正在寻找的结果，并且我没有得到任何错误。

这里是函数

def query(q):
    try:
        with SSHTunnelForwarder(
          (host, 22),
          ssh_username=ssh_username,
          ssh_password=ssh_password,
          ssh_private_key=ssh_private_key,
          remote_bind_address=(localhost, 3306)
        ) as server:
          conn = db.connect(host=localhost,
          port=server.local_bind_port,
          user=user,
          passwd=password,
          db=database)
          pd.read_sql_query(q, conn)
          conn.close()
        return
    except Exception as e:
        print e
        pass

错误来自 print e 语句。

完全错误

Traceback (most recent call last):
  File "C:\MAMP\htdocs\WIGHTcloud\dataLoader\load\loader.py", line 183, in <module>
    query(drop) # drop phases table
  File "C:\MAMP\htdocs\WIGHTcloud\dataLoader\load\loader.py", line 140, in query
    pd.read_sql_query(q, conn)
  File "C:\Python27\ArcGIS10.6\lib\site-packages\pandas\io\sql.py", line 431, in read_sql_query
    parse_dates=parse_dates, chunksize=chunksize)
  File "C:\Python27\ArcGIS10.6\lib\site-packages\pandas\io\sql.py", line 1600, in read_query
    columns = [col_desc[0] for col_desc in cursor.description]
TypeError: 'NoneType' object is not iterable

【问题讨论】：

你能显示完整的跟踪吗？
@Xilpex 编辑原件以显示完整的错误信息

标签： python mysql pandas ssh-tunnel

【解决方案1】：

我会说这是意料之中的。像 SELECT 这样的指令会产生一个输出，包括表头。

而其他 DDL 语句不会产生输出，因此会在 pd.read_sql_query 函数中引发异常。

您应该考虑检索一个游标，并在其上执行 DDL 语句，例如

mycursor = conn.cursor()

sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
val = ("John", "Highway 21")
mycursor.execute(sql, val)

【讨论】：

@wmunsell，你能把它标记为你问题的答案吗？

【解决方案2】：

使用 nilleb 所说的，我将它插入 sshTunnelForwarder 并让它工作。

with sshtunnel.SSHTunnelForwarder(ssh_address_or_host = ssh_host,
        ssh_username = ssh_username,
        ssh_password = ssh_password,
        ssh_pkey = ssh_pkey,
        remote_bind_address=('localhost', 3306),
    ) as tunnel:
        mydb = mysql.connector.connect(
          host=localhost,
          user=sql_username,
          passwd=sql_password,
          database=db_name,
          port=tunnel.local_bind_port
        )
        mycursor = mydb.cursor()
        sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
        val = ("John", "Highway 21")
        mycursor.execute(sql, val)
        mydb.commit()
        print(mycursor.rowcount, "record inserted.")

【讨论】：