填充并选择多个子文档猫鼬

Question

我有一个用户模型

const UserSchema = new mongoose.Schema({
    name: {
        type: String,
        required: true
    } 
    email: {
        type: String,
        required: true,
        maxlength: 128,
        minlength: 5
    }, 
    hashedPassword: {
        type: String,
        required: false
    }
});

module.exports = mongoose.model('users', UserSchema);

和发布模型

const mongoose = require('mongoose');

const PostSchema = new mongoose.Schema({
    description: {
        type: String,
        required: true
    },
    comments: [{
        comment: {
            type: String,
            required: true
        },
        postedBy: {
            type: mongoose.Schema.Types.ObjectId,
            required: true,
            ref: 'users'
        },
        postedOn: {
            type: Date,
            required: true,
            default: Date.now
        }
    }],
    postedBy: {
        type: mongoose.Types.ObjectId,
        required: true,
        ref: 'users'
    }
});

module.exports = mongoose.model('answers', AnswerSchema);

我想从POST的“ postedBy”中获取帖子，还从POST的“ postedBy”中选择“名称和电子邮件”字段。另外，我想填充“ postedBy”（内部注释），然后从“ postedBy”（内部注释）中选择“名称和电子邮件”的相同字段。

期望看到类似的结果

{
    "post": [
        {
            "_id": "*some mongo id*",
            "description": "This is a sample Post for testing",
            "postedBy": {
                "_id": "5e9285669bdcb146c411cef2",
                "name": "Rohit Sharma",
                "email": "rohit@gmail.com"
            },
            "comments": [{
                "comment": "Test One Comment",
                "postedBy": {
                    "_id": "5e9285669bdcb146c411cef2",
                    "name": "Rohit Sharma",
                    "email": "rohit@gmail.com"
                },
            }],
            "postedOn": "2020-04-19T12:28:31.162Z"
        }
    ]
}