如何从 Javascript 中的 JSON 文件中删除 object

Question

So I am trying to delete an Object from a json file in JavaScript and it is proving to be harder than once thought.

This is an example of my JSON file:

 { "tom cruise": { "player": "tom cruise", "team": "buf", "position": "qb", "overall": "82", "OnBlock": true }, "tim tebow": { "player": "tim tebow", "team": "buf", "position": "qb", "overall": "82", "OnBlock": false } }

And here is an example of what I have so far:

 client.block = require ("./jsons/tradeblock.json") if (message.content.startsWith('tb.remove')) { player = message.content.toLowerCase().slice(10) array = player.toLowerCase().split(" - ") team = array[0] position = array[1] player = array[2] overall = array[3] client:block [player] = { player, player: team, team: position, position: overall, overall: OnBlock. false } fs.writeFile ("./jsons/tradeblock,json". JSON.stringify (client,block, null, 4); err => { if (err) throw err. message.channel;send("Removing from block") }); }

So I am wondering if there is a way to check if the property of "OnBlock" is false and if so there a way to delete the entire player from the json.

Answer 1

the way to delete a key (and his value) of a json is delete json[key] try with delete client.block[player]

Answer 2

You can use a simple if condition to check whether the onBlock is false and then use delete operator to delete a specific JSON Key.

client.block = require ("./jsons/tradeblock.json")

if (message.content.startsWith('tb!remove')) {
        player = message.content.toLowerCase().slice(10)
        array = player.toLowerCase().split(" - ")
        team = array[0]
        position = array[1]
        player = array[2]
        overall = array[3]
        client.block [player] = {
            player: player,
            team: team,
            position: position,
            overall: overall,
            OnBlock: false
        }
        if (!client.block[player].onBlock){
           delete client.block[player];
           fs.writeFile ("./jsons/tradeblock.json", JSON.stringify (client.block, null, 4), err => {
            if (err) throw err;
            message.channel.send("Removing from block")
        });
        }
        
    }

Answer 3

You're starting with JSON, so there's no need to fiddle about splitting strings and trying to parse the results. Simply use JSON.parse() , and work with the resulting object:

const srcJSON = '{"tom cruise": {"player": "tom cruise","team": "buf","position": "qb","overall": "82","OnBlock": true},"tim tebow": {"player": "tim tebow","team": "buf","position": "qb","overall": "82","OnBlock": false}}';

let players = JSON.parse(srcJSON);             // Parse JSON into a javascript object

Object.keys(players).forEach(function(key){    // Iterate through the list of player names
    if (!players[key].OnBlock) {               // Check the OnBlock property
        delete players[key]                    // delete unwanted player
    }
});

let output = JSON.stringify(players);          //Convert back to JSON

Answer 4

IMO if you have more then one JSON file which you're going to be reading and writing to, you might as well make a model for it.

You could make an index.js file in ./jsons , with the following contents:

const jsonFile = new (class {
  constructor() {
    this.fs = require('fs');
  }
  get(filePath) {
    return JSON.parse(
      Buffer.from(this.fs.readFileSync(filePath).toString()).toString('utf-8')
    );
  }
  put(filePath, data) {
    return this.fs.writeFileSync(filePath, JSON.stringify(data, null, 4), {
      encoding: 'utf8'
    });
  }
})();

module.exports = class jsons {
  constructor(file) {
    this.file = './jsons/' + file + '.js';
    this.data = jsonFile.get(file);
  }
  get() {
    return this.data;
  }
  add(key, data) {
    this.data[key] = data;
    jsonFile.put(this.file, this.data);
  }
  remove(key) {
    delete this.data[key];
    jsonFile.put(this.file, this.data);
  }
}

Then wherever you use ./jsons you could treat it like a CRUD and it would read/write to the file seamlessly instead of having a bunch of fs.writeFile 's everywhere:

const jsons = require('./jsons')

let client = {};

client.block = new jsons('tradeblock');
// client.foo = new jsons('foo');
// client.bar = new jsons('bar');

// get
let all_clients = client.block.get();

// add (will replace if same key)
let player = 'Loz Cherone';
let team = 'foo team';
let position = 'relative';
let overall = 'dungarees'

client.block.add(player, {
  player,
  team,
  position,
  overall,
  OnBlock: true,
});

client.block.remove(player);

Your code would look like:

const jsons = require('./jsons')

let client = {};
client.block = new jsons('tradeblock');

if (message.content.startsWith('tb!remove')) {
  let player = message.content.toLowerCase().slice(10);
  const array = player.toLowerCase().split(' - ');
  if (array.length >= 3) {
     player = array[2];
     client.block.remove(player);
     message.channel.send('Removing from block');
  } else {
     message.channel.send('Invalid block structure');
  }
}

If you want something more robust, you could use lib like conf .