如何摆脱 JSON 中多余的花括号？

Question

I'm basically creating a contact book, and I want to do it storing data on JSON to practice it. I have sort a code that allows it from a dictionary, but the problem is that when I rerun the script, another dictionary is appended into the existing one, creating a couple of extra braces which throws the error "End of file expected."

This is the code:

import json


new_contacts = {}


def contacts():
    while True:
        name = input("Contact's name: ")
        email = input("Email: ")
        number = input("Phone number: ")
        new_contacts[name] = {"email": email, "number": number}
        
        """cursor.execute(
            'INSERT INTO contacts VALUES (?, ?, ?)',
            (name, email, number)
            )"""
        restart_or_not = input("Continue? y/n ").lower()

        if restart_or_not == "y":
            print(new_contacts)
            continue
        else:
            with open('contact_book.json', 'a') as file:
                json.dump(new_contacts, file, indent=4)
            break


contacts()

And this is a sample of a JSON that comes out from it:

{
    "d": {
        "email": "e",
        "number": "3"
    },
    "h": {
        "email": "y",
        "number": "6"
    },
    "f": {
        "email": "r",
        "number": "3"
    },
    "n": {
        "email": "j",
        "number": "9"
    }
}{
    "g": {
        "email": "j",
        "number": "0"
    }
}

The first four entries don't create any problem because they are appended in the same run, but if I quit the program and rerun it (example "g") then the new dictionary creates the conflict. Any tips?

Answer 1

One way of doing it, is before adding to the file, you delete the last closing bracket } and before dumping, you cast your dict into a string and remove the first bracket using this your_string[1:] .

The other way which I coded for you, is you load the json into a variable, add the new inputs and then re dump it into the file

import json

from os import path # it helps to check if file exists


new_contacts = {}

def contacts():
    while True:
        name = input("Contact's name: ")
        email = input("Email: ")
        number = input("Phone number: ")
        new_contacts[name] = {"email": email, "number": number}
        
        """cursor.execute(
            'INSERT INTO contacts VALUES (?, ?, ?)',
            (name, email, number)
            )"""
        restart_or_not = input("Continue? y/n ").lower()

        if restart_or_not == "y":
            print(new_contacts)
            continue
        else:
            # if the file doesn't exist, write an empty json object into it
            # which will make it easier later to load data from
            if not path.exists('contact_book.json'):
                with open('contact_book.json', 'w+') as file:
                    json.dump({}, file)
            # This loads the data into the variable dict called loaded_data
            with open('contact_book.json', 'r') as file:
                loaded_data = json.load(file)
                for k, v in new_contacts.items():
                    loaded_data[k] = v
            # redumps your data into the json file
            with open('contact_book.json', 'w') as file:
                json.dump(loaded_data, file, indent=4)
            break

contacts()

Answer 2

Just updated a bit of the else part of your code. It checks whether a file exists or not . If it exists, the contents of the file is read and updated and then dumped into the file. If it doesn't exist, your old code will be executing.

if os.stat("contact_book.json").st_size != 0:
    with open('contact_book.json', 'r+') as file:
        contents = json.loads(file.read())
        contents.update(new_contacts)
        file.seek(0)
        json.dump(contents, file, indent=4)
else:
        with open('contact_book.json', 'a') as file:
        json.dump(new_contacts, file, indent=4)
        break

Honestly, not an efficient solution. But this should be able to invoke an idea.