Python: TypeError: a bytes-like object is required, not 'tuple'

Question

我在下面有一些代码，它查询数据库并提取 BLOB。我想将此 BLOB 数据保存为文件，但我无法这样做。我做了一些研究并尝试了各种示例代码，但似乎没有任何效果。

import cx_Oracle
import db_config

con = cx_Oracle.connect(db_config.user, db_config.pw, db_config.dsn)
cur = con.cursor()

def writeTofile(data, filename):
    print(data)
    print(filename)
    with open(filename, "wb") as file:
        file.write(data)
    print("Stored blob data into: ", filename, "\n")

def output_type_handler(cursor, name, default_type, size, precision, scale):
    if default_type == cx_Oracle.DB_TYPE_CLOB:
        return cursor.var(cx_Oracle.DB_TYPE_LONG, arraysize=cursor.arraysize)
    if default_type == cx_Oracle.DB_TYPE_BLOB:
        return cursor.var(cx_Oracle.DB_TYPE_LONG_RAW, arraysize=cursor.arraysize)

con.outputtypehandler = output_type_handler

   print("Querying data...")
cur.execute("select payload from table where id=101")
(blob_data) = cur.fetchone()
print("BLOB length:", len(blob_data))
print("BLOB data:", blob_data)
payload = blob_data
trigger = "C:\Temp\Training\Python\trigger.bin"
print(trigger)
writeTofile(payload, trigger)

我得到的回复如下：

Enter password for DataBase:
Querying data...
BLOB length: 1
BLOB data: (b'5468616e6b7320666f722074616b696e67207468652074696d6520746f2068656c702c20697473206d756368206170726963617465642e',)
C:\Temp\Training\Python\trigger.bin
(b'5468616e6b7320666f722074616b696e67207468652074696d6520746f2068656c702c20697473206d756368206170726963617465642e',)
C:\Temp\Training\Python\trigger.bin
Traceback (most recent call last):
  File "C:\Temp\Training\Python\python-cx_Oracle-main\samples\tutorial\read_blob3.py", line 39, in <module>
    writeTofile(payload, trigger)
  File "C:\Temp\Training\Python\python-cx_Oracle-main\samples\tutorial\read_blob3.py", line 20, in writeTofile
    file.write(data)
TypeError: a bytes-like object is required, not 'tuple'

我真的不明白为什么提到 writeTofile(payload, trigger) 因为我在 wrtietofile 函数中的打印语句显示数据已传递，我错过了什么？

我以为我必须将数据转换为字节数组，但那给了我一个不同的错误；

TypeError: 'bytes' object cannot be interpreted as an integer

非常感谢任何帮助。

Answer 1

payload的类型是元组，你需要调用函数，

writeTofile(payload[0], trigger)

Answer 2

您正在尝试将元组写入文件：file.write(data)。您的数据库查询 returns 一个结果为一个元组。您必须像这样提取这个结果，例如：(blob_data) = cur.fetchone()[0]。或者，您可以像这样在写入函数中循环结果：

with open(filename, "wb") as file:
    for datapoint in data:
        file.write(datapoint + b"\n")

当您有多个数据点要写入文件时，这也适用。

Python: TypeError: a bytes-like object is required, not 'tuple'

Python: TypeError: a bytes-like object is required, not 'tuple'

python

oracle

blob