Using pickles in Python

Question

I am trying to use a pickle in Python and I am failing miserably. For each error that I overcome I get another message. I get the following message when I run my code. I am getting a syntax error for my use of 'else'. Why is that?

I am a newb to Python but I can't figure out what am I doing wrong?

import pickle
def main():
 file_mail = open('email.dat','wb')
 save_data(file_mail)
 file_mail.close()
def save_data(file):
 email = {}
 count = 0
 while count == 0:
 print('Add an email: 1')
 print('Modify an email: 2')
 print('Delete an email: 3')
 print('Display the list: 4\n')
 choice = input('Enter a number from the list above:')
 if int(choice)== 1:
 name = input('Name:')
 mail = input('E-mail:')
 email[name] = mail
 print('Added Successfully')
 if int(choice) == 2:
 name = input('Name:')
 mail = input('E-mail:')
 email[name] = mail
 print('Modified Successfully')
 if int(choice) == 3:
 name = input('Name:')
 mail = input('E-mail:')
 email[name] = mail
 print('Deleted Successfully')
 if int(choice) == 4:
 print(email)
 else:
 print('Invalid selection')
 c = input('Do you want to continue y/n: ')
 if c.upper() == 'N':
 count = 1
 print('Invalid Letter')
 file_mail = open('email.dat','wb')
 pickle.dump(email,file_mail)
 file_mail.close()
main()

• umutto: When reading (at your 3rd line), you are opening your file with 'wb' which means write binary mode. Change that to 'rb' - read binary mode.

Answer 1

Try to use rb mode when reading a pickle-containing file :

file_mail = open('email.dat','rb')
email = pickle.load(file_mail)

And use wb mode when writing a pickled representation of obj to the open file object:

output = open('data.pkl', 'wb')
pickle.dump(data1, output)

See more details from pickle example.

• Part_Time_Nerd: That was my original but I got the error message email = pickle.load(file_mail) EOFError: Ran out of input
• McGrady: @BWMustang13 you should check that the file is not empty, that's why you got the EOFError error.
• McGrady: Have look at this answer Why do I get "Pickle - EOFError: Ran out of input" reading an empty file?
• Part_Time_Nerd: I believe I ran it as the post suggested but I got the same error.
• Part_Time_Nerd: I updated my question to incorporate a slightly different approach by segregating i into 2 separate functions. See my changes above, but I am getting an invalid syntax error with the else statement. Why is that? It might be because I have been looking at code the last 18 hours but it looks like the indentations should be correct.

Answer 2

Thanks @McGrady! Here is the final answer I got.

import pickle
def main():
 file_mail = open('email.dat','wb')
 save_data(file_mail)
 file_mail.close()
def save_data(file):
 email = {}
 count = 0
 while count == 0:
 print('Add an email: 1')
 print('Modify an email: 2')
 print('Delete an email: 3')
 print('Display the list: 4\n')
 choice = input('\nEnter a number from the list above:')
 if int(choice)== 1:
 name = input('Name:')
 mail = input('E-mail:')
 email[name] = mail
 print('Added Successfully\n')
 else:
 if int(choice) == 2:
 name = input('Name:')
 mail = input('E-mail:')
 if name in email:
 email[name] = mail
 print('Modified Successfully\n')
 else:
 print('Name not found')
 else:
 if int(choice) == 3:
 name = input('Enter name you want to delete:')
 if name in email:
 email.pop(name)
 print('Deleted Successfully\n')
 else:
 print('Name not found') 
 else:
 if int(choice) == 4:
 print(email)
 else:
 print('Invalid selection\n')
 c = input('Do you want to continue y/n: ')
 if c.upper() == 'N':
 count = 1
 else:
 if c.upper() == 'N':
 count = 1
 print('Invalid Letter')
 file_mail = open('email.dat','wb')
 pickle.dump(email,file_mail)
 file_mail.close()
main()