Why do my python dictionaries keep overwriting

Question

What I am trying to do is create a dictionary within a dictionary. It is supposed to be a movie lover's club in which you can add movies to a member's account, but when I try to add it, it gets overwritten. Below is my code:

import sys

movies = {}


def option_one():
    print('Club Members')
    print('=' * 12)
    for name in movies:
        print(name)
    application()


def option_two():
    name = input('Please enter the user\'s name: ')
    for movie in movies[name]:
        title = movies[name][movie]
        watch = movies[name][movie]['Watched']
        rate = movies[name][movie]['Rating']
        print('Movie', 'Rating', 'Watched', sep=' ' * 5)
        print('=' * 30)

        print(movie, movies[name][movie]['Rating'], movies[name][movie]['Watched'], sep=' ' * 8)

    application()


def option_three():
    name = input('Please enter the member\'s name: ')

    if name in movies:
        movie = input('Please enter the name of the movie: ')
        movies[name][movie]['Watched'] = movies[name][movie]['Watched'] + 1
        for movie in movies[name]:
            if movie not in movies[name][movie]:
                print('Movie not found. ')
            else:
                print('Times watched incremented. ')
    else:
        print('Sorry, member not found. ')
    application()


def option_four():
    name = input('Please enter the member\'s name: ')

    # if the name exists in movies add the movie
    if name in movies:
        # enter information and update dictionary
        movie_title = input('Enter movie name: ')
        times_watched = int(input('Enter times watched: '))
        rating = input('Enter rating: ')
        add_movie = {name: {movie_title: {'Watched': times_watched,
                                          'Rating': rating}}}
        movies.update(add_movie)
        print('Movie added')

    # if name not in movies print member not found call option 4 again
    else:
        print('Member not found')
        option_four()
    application()


def option_five():
    name = input('Enter new member name: ')
    nameDict = {name: ''}

    # update the movies dictionary with name dictionary as key
    movies.update(nameDict)
    print('Member added')
    application()


def application():
    print('=' * 33)
    print('Movie Lover\'s club')
    print('=' * 33)
    print('1. Display all club_members.')
    print('2. Display all movie information for a member.')
    print('3. Increment the times a specific movie was watched by a member.')
    print('4. Add a movie for a member.')
    print('5. Add a new member.')
    print('6. Quit')
    print('=' * 33)

    # get name input for selection
    name_selection = (input('Please enter a selection: '))

    # if statement directing name choice to corresponding method
    if name_selection == '1':
        option_one()

    if name_selection == '2':
        option_two()

    if name_selection == '3':
        option_three()

    if name_selection == '4':
        option_four()

    if name_selection == '5':
        option_five()

    if name_selection == 'Q':
        print('=' * 33)
        print('Thank you for using Movie Lover\'s Club')
        print('=' * 33)
        sys.exit()
    else:
        input('Pick a number between 1 and 5 or Q to exit program. Press enter to continue.')


application()

The code above is working as expected but it will not add movie titles only overwrite them. Any help is very much appreciated.

Answer 1

Edit2: With your updated code, here's the solution to your problem. You were actually really close, the only issue was that you were using .update on the movies dictionary, rather than the movies[name] dictionary, so you would replace movies[name] with your new movie dict each time. The solution here is to update movies[name] instead. Also, I made a change to your option_five function so that when you add a new member, they have an empty dictionary by default rather than an empty string, so it can be updated:

def option_four():
    name = input('Please enter the member\'s name: ')

    # if the name exists in movies add the movie
    if name in movies:
        # enter information and update dictionary
        movie_title = input('Enter movie name: ')
        times_watched = int(input('Enter times watched: '))
        rating = input('Enter rating: ')

        # notice how I got rid of {name: ...} and instead only used the movie
        new_movie = {movie_title: {'Watched': times_watched, 'Rating': rating}}
        # now update the user's movie dict rather than the entire movies dict
        movies[name].update(new_movie)

    # if name not in movies print member not found call option 4 again
    else:
        print('Member not found')
        option_four()
    application()

def option_five():
    name = input('Enter new member name: ')
    nameDict = {name: {}} # notice that I replaced '' with {}

    # update the movies dictionary with name dictionary as key
    movies.update(nameDict)
    print('Member added')
    application()

Now you can add movies for a user at will without overwriting

Answer 2

The reason it gets overwritten is because you overwrite a member's list every time you would like to add a new movie. Specifically, when you execute:

add_title = movies[name] = {movie_title: {'Watched': '', 'Rating': ''}}

movie[name] now only contains {movie_title: {'Watched': '', 'Rating': ''}}

Here is a new version of your code:

def option_four():
    name = input('Please enter the member\'s name: ')

    # enter information 
    movie_title = input('Enter movie name: ')
    times_watched = int(input('Enter times watched: '))
    rating = input('Enter rating: ')

    if name not in movies:
        movies[name] = {}

    #create the movie title value dictionary make 'movie_title input the name of dict
    movies[name][movie_title] = {'Watched': '', 'Rating': ''}

    #add watched and rating values to the movie_title dict
    movies[name][movie_title]['Watched'] = times_watched
    movies[name][movie_title]['Rating'] = rating