CODEWITHSUNDEEP
pythonjson
Saksham Chaturvedi
Saksham Chaturvedi

Reputation: 13

Updating Dictionaries permanently in Python

I want to update the keys and values in my dictionary permanently, I have a dictionary stored in a variable, which has now 2 keys and values, I want to add keys and values, by input, and want them to be stored in the dictionary forever, even if I restart the program, What happens now is The keys and values given by the user are inserted successfully into the dictionary, but as soon as I restart the program, It is again back to the 2 values which I gave in the program.

Code:

      mails = {'robin': '[email protected]', 'michael': '[email protected]'}
      cont_name = input('Enter the contact name: ')  {Jessey}
      cont_mail = input('Enter the mail-id: ')       {[email protected]}
      dict1 = {cont_name:cont_mail} 
      mails.update(dict1)
      print (mails)

(This gives me correct output)

Output: {'robin': '[email protected]', 'michael': '[email protected]', 'Jessey': '[email protected]'}

but as soon as I Restart my program, and print the dictionary (mails), it shows me this output:

{'robin': '[email protected]', 'michael': '[email protected]'}

Answers would be appreciated, Thanks in Advance!

Upvotes: 1

Views: 426

Answers (4)

VDes
VDes

Reputation: 66

shelve, pickle, persidict are all good options for you.

Upvotes: 0

one
one

Reputation: 62

I guess pickle is a good solution for this.

import pickle, os
  
def load_emails(mail_file): 
    if os.stat(mail_file).st_size == 0:
        return {}
    mails = pickle.load(open(mail_file, 'rb')) 
    return mails

def store_emails(mails, mail_file):
    pickle.dump(mails, open(mail_file, 'wb'))                      

mail_file = "userdata"
mails = load_emails(mail_file)

cont_name = input('Enter the contact name: ')  
cont_mail = input('Enter the mail-id: ') 
mails[cont_name] = cont_mail

store_emails(mails, mail_file)

You need to call the store_emails() function every time you add a new key to the dictionary.

Upvotes: 0

user14185615
user14185615

Reputation:

Variables in Python are temporary. If you want them to be permanent, you could store the data in a JSON file or in your database. Or you could use Daweo's method, which I recommend, where you use shelve, a built-in Python module.

Upvotes: 1

Daweo
Daweo

Reputation: 36440

want them to be stored in the dictionary forever, even if I restart the program

You need what is called data persistence, you can use built-in shelve module for that. Consider following simple example which provide favorite color of user if known otherwise ask for one and save it

import shelve
d = shelve.open("userdata")
name = input("What is your name?")
if name in d:
    print("Your favorite color is", d[name])
else:
    color = input("What is your favorite color?")
    d[name] = color
d.close()

where userdata is name of file where data are stored.

Upvotes: 0

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