Question

我正在努力实现这个功能：

更改目录，如果它们存在于FTP中，如果不存在，则创建它们并将目录更改为。

def directory_exists(self, directory_name):
        if directory_name in ftp.nlst():
            self.change_directory(directory_name)
        else:
            self.make_directory(directory_name) and self.change_directory(directory_name)

函数调用：

def make_directory(self, directory):
        if ftp.mkd(directory):
            self.log_message("Directory {0} created successfully".format(directory))
            return True
        else:
            self.log_message("Failed creating directory")
            return False

def change_directory(self, directory):
        if ftp.cwd(directory):
            self.log_message("Current Directory is now {0}".format(ftp.pwd()))
        else:
            self.log_message("Can't change Directory")

如果任何新目录作为parameter给出，则此代码当前有效，如果给出了现有目录，则会返回此回溯。

Traceback (most recent call last):
  File "C:/Users/Ajay/PycharmProjects/database/config.py", line 17, in <module>
    ftp_obj.directory_exists(directory)
  File "C:\Users\Ajay\PycharmProjects\database\ftp.py", line 51, in directory_exists
    self.make_directory(directory_name) and self.change_directory(directory_name)
  File "C:\Users\Ajay\PycharmProjects\database\ftp.py", line 34, in make_directory
    if ftp.mkd(directory):
  File "C:\Python27\lib\ftplib.py", line 568, in mkd
    resp = self.sendcmd('MKD ' + dirname)
  File "C:\Python27\lib\ftplib.py", line 244, in sendcmd
    return self.getresp()
  File "C:\Python27\lib\ftplib.py", line 219, in getresp
    raise error_perm, resp
ftplib.error_perm: 550 Can't create directory: File exists

我的代码函数调用逻辑：

directory = '/new'
ftp_obj.directory_exists(directory)

Answer 1

我通过小技巧解决了这个问题。

def directory_exists(self, directory_name):
        new_dir_name = directory_name.strip("/")
        if new_dir_name in ftp.nlst():
            self.change_directory(directory_name)
        else:
            self.make_directory(directory_name)
            self.change_directory(directory_name)

现在，一切正常。

Answer 2

可能ftp.nlst以与您正在使用的格式不完全匹配的格式返回目录名称（'newdir'与'./newdir'对比'/ full / path / newdir'）。但是，当您尝试创建已存在的目录时，ftp.mkd会抛出异常，而不是返回False。考虑到这一点，您可以更改directory_exists以始终尝试创建目录，然后更改chdir而不管它是否成功：

def directory_exists(self, directory_name):
    try:
        ftp.mkd(directory_name)
        self.log_message("Directory {0} created successfully".format(directory))
    except ftplib.error_perm:
        pass #you could check for other errors also
    self.change_directory(directory_name)

在Python中更改目录，不起作用

2 个答案: