javascript - 从其他数组中的多个对象创建对象数组

Question

假设我必须向列表中明天有约会的人发送电子邮件， 然而，当我编写电子邮件主题时，我想知道谁明天有多个约会，以便我可以配置主题。 我也不想一次发送多封电子邮件。我想发送一封电子邮件，说明您明天有一个约会或多个约会。 (如果知道这些约会的 ID 也很好。)

所以我有以下内容:

AllAppointments: [
    {
        id: 23,
        name: "John",
        email: "John@domain.com",
        appointment_date: tomorrow,
        appointment_category: 3,
        time: "morning"
    }, {
        id: 17,
        name: "Alex",
        email: "Alex @domain.com",
        appointment_date: tomorrow,
        appointment_category: 3,
        time: "morning"
    },


    {
        id: 22,
        name: "Bob",
        email: "Bob@domain.com",
        appointment_date: tomorrow,
        appointment_category: 5,
        time: "morning"
    }, {
        id: 35,
        name: "John",
        email: "John@domain.com",
        appointment_date: tomorrow,
        appointment_category: 4,
        time: "afternoon"
    }

]

我想要这些

MultipleAppointments : [

        {
            ids :[23,35],
            name : John,
            email : John@domain.com,
            appointment_date : tomorrow,
            appointment_categories: [ 3, 5  ]
        }
]

singleAppointments : [ 

        { 
            id: 17,
            name : “Alex",
            email : “Alex@domain.com",
            appointment_date : tomorrow,
            appointment_category:  3,
            time: “morning"
        },


        { 
            id: 22,
            name : “Bob",
            email : “Bob@domain.com",
            appointment_date : tomorrow,
            appointment_categories:  5,
             time: “morning"
        }


]

Answer 1

首先告诉您存储这些数据的位置。蒙戈数据库？ mysql？内存？

那就换个思维方式吧。您需要知道的是哪封电子邮件发送了多于 1 个通知，而不是谁有多少次 session 。我建议您使用一个多维表，而不是 2 个一维表:

mails: {
 'John@domain.com': [
{
        id: 23,
        name: "John",
        email: "John@domain.com",
        appointment_date: tomorrow,
        appointment_category: 3,
        time: "morning"
    },  {
        id: 35,
        name: "John",
        email: "John@domain.com",
        appointment_date: tomorrow,
        appointment_category: 4,
        time: "afternoon"
    }
]
'Alex@domain.com': [{
        id: 17,
        name: "Alex",
        email: "Alex@domain.com",
        appointment_date: tomorrow,
        appointment_category: 3,
        time: "morning"
    }
]
'Bob@domain.com': [{
        id: 22,
        name: "Bob",
        email: "Bob@domain.com",
        appointment_date: tomorrow,
        appointment_category: 5,
        time: "morning"
    }]
}

而且这样的东西很容易创建。

let mails = {};
AllAppointments.forEach(one=> {
  if(!mails[one.email])
    mails[one.email] = [];
  mails[one.email].push(one)
})
for(let email in mails)
  sendMail(mails[email])