无法访问预保存中间件猫鼬中的架构属性

Question

遇到一个奇怪的问题，我无法访问预保存中间件中的任何架构属性。当我将鼠标悬停在该属性上时，我可以看到此错误：

  

“文档类型上不存在属性createdAt”

以下是我的代码：

import * as mongoose from 'mongoose';
var StaffSchema = new mongoose.Schema({
    name : {
        firstName: {
            type: String,
            required: true
        },
        lastName: {
            type: String,
            required: true
        },
        middleName: {
            type: String,
            required: true
        },
        email: {
            type: String,
            required: true
        },
        signatureLine: {
            type: String,
            required: true
        },
        isActive: {
            type: Boolean,
            default: true
        },
        isWithoutSupervisorCoSign: {
            type: Boolean,
            default: false
        },
        isShowInSchedule: {
            type: Boolean,
            default: false
        }
    },
    createdAt: {
        type: Date
    },
    updatedAt: {
        type: Date
    }
});

StaffSchema.pre('save', function(next) {
// do stuff
this.createdAt = Date.now();
next();
});

export default mongoose.model('staff', StaffSchema);