Why is this python function not reading my json File string properly?

Question

So I have a unique player ID string that is stored in a JSON file after it detects on start-up that the player is new to the game.

def checkIfPlayerIsNew():

    if os.path.exists("myJson.json"):
        print('file exists')

        k = open('myPlayerIDs.json')
        print(k.read())
        #print("This is the k value: {}".format(code))
        #code = json.dumps(k)

        getData(k.read())

    else:
        print('file does not exist')

        f = open('myJson.json', 'x')  #creates the file if it doesn't exist already
        f.close()

        file = open('myPlayerIDs.json', 'w')
        file.write(json.dumps(str(uuid.uuid4())))
        file.close

        checkIfPlayerIsNew()

Now, if it detects that the player is not new it gets the ID from the JSON File and passes it to the get data function below

def getData(idCode = "X"):

    print('the id code is this: {}'.format(idCode))
    outputFile = json.load(open('myJson.json')) 
    for majorkey, subdict in outputFile.items():
        if majorkey == idCode: 
            for subkey, value in subdict.items():
                print('{} = {}'.format(subkey, value))
                #playerData[subkey] = value
        else:
            print("ID Does not match") 
            break

The problem is that when I check the id code in the get data function it prints out a blank space as if the id code has been changed to nothing (which I can't figure out why it has done that) and prints this out to the terminal:

The playerID JSON File:

How would multiple player IDs be represented in your JSON file? Also, please fix your code's indentation. — jarmod, May 20 '22 at 13:26
@jarmod good point, was just making this as an example for myself to learn python file reading with JSON. also the indentation looks fine to me except the def part of the function being in line with the if statement. which is just me spacing it for my question. — Astrum, May 20 '22 at 13:42
The posted code is not indented correctly. It's important in Python and on StackOverflow. — jarmod, May 20 '22 at 13:45

Wacov · Accepted Answer · 2022-05-20T13:35:53.993

2

You can't read() a file twice without seeking back to the start. The right thing to do here is to read the file into a variable:

if os.path.exists("myJson.json"):
    print('file exists')

    # Read file into a variable and use it twice
    with open('myPlayerIDs.json', 'r') as k:
        data = k.read()

    print(data)
    getData(data)
#...

edited May 20 '22 at 13:35

answered May 20 '22 at 13:26

Wacov

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2
9

2

`k = open()` is bad practice. Either use `with` as a context manager or make sure you `k.close()` after you read it – Lukas Schmid May 20 '22 at 13:30
Good point, edited. – Wacov May 20 '22 at 13:36
I keep thinking once I've opened the file its open until I close it, thanks for your answer – Astrum May 20 '22 at 13:37
@LukasSchmid if I use it the 'with' way why is that better? – Astrum May 20 '22 at 13:43
`with` auto-closes the file for you when the `with` block ends, so you don't need to remember to call `close()`. As for why you should close the file: https://stackoverflow.com/questions/25070854/why-should-i-close-files-in-python – Wacov May 20 '22 at 14:13

Why is this python function not reading my json File string properly?

1 Answers1