python-3.x - 使用 Cloud Functions 在 Cloud Storage 中创建 csv 文件

Question

我一直在尝试从 Cloud Functions 中的字符串创建一个 csv 文件。它将文件临时存储在/tmp 文件夹中。然后文件进入存储桶。

以下是我的代码 -

def upload_blob(bucket_name, source_file_name, destination_blob_name):

    storage_client = storage.Client()
    bucket = storage_client.get_bucket(bucket_name)
    blob = bucket.blob(destination_blob_name)
    blob.upload_from_file(source_file_name)

message = "Data for CSV file"
csv = open('test.csv', "w")    #ERROR HERE
csv.write(message)
with open('/tmp/test.csv', 'r') as file_obj:
    upload_blob('test-bucket', file_obj, 'test.csv')

我收到以下错误 -

File "/user_code/main.py", line 30, in hello_main csv = open('test.csv', 
"w") OSError: [Errno 30] Read-only file system: 'test.csv'

如何使这个文件可写？

Answer 1

如 @saccodd说问题是你在 /tmp directory中只有写权限.所以更换:

csv = open('test.csv', "w") 

和:

csv = open('/tmp/test.csv', "w") 

将解决错误，但建议在再次处理之前关闭文件。引用 Python official documentation :

It is good practice to use the with keyword when dealing with file objects. The advantage is that the file is properly closed after its suite finishes, even if an exception is raised at some point. Using with is also much shorter than writing equivalent try-finally blocks

所以最好更换

csv = open('test.csv', "w") #ERROR HERE 
csv.write(message) 

和:

with open('/tmp/test.csv', "w") as csv: 
    csv.write(message)