Change directories in Python, not working

Question

I am trying hard to implement this function:

change the directories if they are present in FTP and if not, create them and change directories to it.

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)

Function calls:

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")

This code currently works if any new directory is given as the parameter and if the existing directory is given, this traceback comes.

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

My Code Function call logic:

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

Answer 1

I solved this by little trick.

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)

Now, Everything works fine.

Answer 2

Probably ftp.nlst returns the directory names in a format that does not exactly match the format you are using ('newdir' vs. './newdir' vs. '/full/path/newdir'). However, ftp.mkd throws an exception, rather than returning False, when you try to create a directory that already exists. With this in mind, you could just change directory_exists to always try to create the directory, and then chdir regardless of whether it succeeds:

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)