从 JSON Python 中删除元素

Question

我正在尝试为我的 discord 机器人创建一个命令，从服务器中删除一个所谓的“派系”。派系存储在一个整洁的 JSON 中，像这样

{
    "Meme Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    },
    "Gamer Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    }
}

这是应该删除派系的代码：

@commands.command(aliases=["d"])
async def delete(self, ctx, *, name: str):
    with open("configs/factions.json", "r+") as f:
        factions_json = json.load(f)
        factions_list = list(factions_json.keys()) # loads JSON keys as list

        name_capital = name.title()
        if name_capital in factions_list:
            member_role = ctx.guild.get_role(factions_json[name_capital]["member role"])
            owner_role = ctx.guild.get_role(factions_json[name_capital]["owner role"]) 

            await member_role.delete() # deletes faction role
            await owner_role.delete() # deletes faction owner role

            # JSON remove code
            factions_json.pop(name_capital) 
            f.seek(0)
            json.dump(factions_json, f, indent=4)

            await ctx.message.add_reaction("✅")

问题是，它不是从 JSON 中删除派系，而是将另一个版本的 JSON 附加到末尾，而不是派系。像这样：

{
    "Meme Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    },
    "Gamer Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    }
}{
    "Meme Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    },
}

如何覆盖 JSON 而不是附加到它？

Answer 1

当您以r+ 模式打开文件时，您打开它是为了读写。

然后，您读取文件，因此流位置移动到文件末尾。

然后，您写入文件，因此它写入当前流位置，即文件末尾。

要解决此问题，您有两种选择：

选项 1：

Seek the position 使用f.seek(0) 指向文件的开头。然后写入文件。这样做的问题是它只会覆盖需要覆盖的文件以转储新的 json。文件的其余部分不会被覆盖，所以无论如何你都会得到乱码的 json。要解决此问题，您需要截断文件的其余部分。

with open('factions.json', 'r+') as f:
    j = json.load(f)
    j.pop("Meme Faction")
    f.seek(0)
    json.dump(j, f, indent=4)
    f.truncate()

给出输出：

{
    "Gamer Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    }
}

选项 2

关闭原始文件句柄并打开一个新的只写文件句柄。然后写入文件。

with open('factions.json', 'r+') as f:
    j = json.load(f)

j.pop("Meme Faction")
with open('factions.json', 'w') as f:
    json.dump(j, f, indent=4)

给出输出：

{
    "Gamer Faction": {
        "members": [],
        "owner": 429935667737264139,
        "description": "This is the description :smile:",
        "member role": 773580603072839710,
        "owner role": 773580603605516290
    }
}