How to save user id only once in json file discord.py

The code I have saves the same user in the json file again:

@client.command()
async def Shibaku1(ctx, coin1, coin2, coin3, coin4, coin5, coin6):
    with open('Shibaku1.json', 'r') as f:
      coins_data = json.load(f)
    coins_data[ctx.author.id] = (coin1, coin2, coin3, coin4, coin5, coin6)
    with open('Shibaku1.json', 'w') as f:
      json.dump(coins_data, f)

I tried making an if statement in order to not happen, but it didn’t seem to work

>Solution :

Python automatically updates keys in dictionary if they exist.

You should convert ctx.author.id to str using str(ctx.author.id):

@client.command()
async def Shibaku1(ctx, coin1, coin2, coin3, coin4, coin5, coin6):
    with open('Shibaku1.json', 'r') as f:
      coins_data = json.load(f)
    coins_data[str(ctx.author.id)] = (coin1, coin2, coin3, coin4, coin5, coin6)
    with open('Shibaku1.json', 'w') as f:
      json.dump(coins_data, f)