如何在JS中仅当ban相关字段非空时向对象添加ban属性？

背景信息 #

数据库查询SQL #

SELECT users.skin, users.name, users.money, users.money_bank, users.fraction_id, users.fraction_id2, users.family_id, users.online_time, ban_list.ban_from, ban_list.ban_to, ban_list.count, ban_list.datetime, ban_list.reason FROM users LEFT OUTER JOIN ban_list ON users.name = ban_list.ban_to WHERE users.social = ? LIMIT 3

查询结果说明 #

查询返回结果中，ban_from、count、datetime、reason字段可能为NULL（因使用LEFT OUTER JOIN关联表）。

当前构造JSON的JavaScript代码 #

let charackters = [];

let nameData =  row['name'].split(" ");

charackters.push({
    spawnIndex: 0,
    name: nameData[0],
    surname: nameData[1],
    level: 0,
    cash: row['money'],
    bank: row['money_bank'],
    gender: gender,
    fraction: fraction,
    family: row['family_id'],
    playedTime: row['online_time'],
    ban: {
        penalty: row['count'],
        reason: row['reason'],
        admin: row['ban_from'],
        dateOfBan: row['datetime']
    }
});

let charackterObject = {
    characters: charackters
}  

let charackterJson = JSON.stringify(charackterObject);

问题需求 #

仅当row['count']、row['reason']、row['ban_from']、row['datetime']全部不为NULL时，才给构造的角色对象添加ban属性，否则不包含该属性。

解决方案 #

方法1：先构建基础对象，再条件追加属性 #

先创建不含ban的基础角色对象，判断字段全部非空后再添加ban属性，逻辑直观易懂：

let charackters = [];
let nameData = row['name'].split(" ");

// 构建基础角色对象
const character = {
    spawnIndex: 0,
    name: nameData[0],
    surname: nameData[1],
    level: 0,
    cash: row['money'],
    bank: row['money_bank'],
    gender: gender,
    fraction: fraction,
    family: row['family_id'],
    playedTime: row['online_time']
};

// 校验ban相关字段是否全部非空
const hasValidBan = row['count'] !== null && 
                   row['reason'] !== null && 
                   row['ban_from'] !== null && 
                   row['datetime'] !== null;

if (hasValidBan) {
    character.ban = {
        penalty: row['count'],
        reason: row['reason'],
        admin: row['ban_from'],
        dateOfBan: row['datetime']
    };
}

charackters.push(character);

let charackterObject = { characters: charackters };  
let charackterJson = JSON.stringify(charackterObject);

方法2：利用ES6展开运算符实现紧凑写法 #

通过展开运算符，在对象字面量中动态决定是否添加ban属性，代码更简洁：

let charackters = [];
let nameData = row['name'].split(" ");

// 校验ban相关字段是否全部非空
const hasValidBan = row['count'] !== null && 
                   row['reason'] !== null && 
                   row['ban_from'] !== null && 
                   row['datetime'] !== null;

charackters.push({
    spawnIndex: 0,
    name: nameData[0],
    surname: nameData[1],
    level: 0,
    cash: row['money'],
    bank: row['money_bank'],
    gender: gender,
    fraction: fraction,
    family: row['family_id'],
    playedTime: row['online_time'],
    // 满足条件则展开ban对象，否则展开空对象（不添加属性）
    ...(hasValidBan ? {
        ban: {
            penalty: row['count'],
            reason: row['reason'],
            admin: row['ban_from'],
            dateOfBan: row['datetime']
        }
    } : {})
});

let charackterObject = { characters: charackters };  
let charackterJson = JSON.stringify(charackterObject);

内容的提问来源于stack exchange，提问作者Danuh xux