mongoose字符串到ObjectID

您要使用默认导出：

import mongoose from 'mongoose';

之后，

mongoose.Types.ObjectId

import mongoose from 'mongoose';console.log( mongoose.Types.ObjectId('578df3efb618f5141202a196') );

编辑： 完整示例（已通过测试

mongoose@4.5.5

import mongoose from 'mongoose';mongoose.connect('mongodb://localhost/test');const Schema = mongoose.Schema;var comments = new Schema({    user_id:  { type: Schema.Types.ObjectId, ref: 'users',required: [true,'No user id found']},    post: { type: Schema.Types.ObjectId, ref: 'posts',required: [true,'No post id found']}});const commentsModel = mongoose.model("comments", comments);let comment = new commentsModel;let str = '578df3efb618f5141202a196';comment.user_id = str;comment.post = str;comment.save().then(() => console.log('saved'))   .catch(e => console.log('Error', e));

数据库显示如下：

mb:test$ db.comments.find().pretty(){    "_id" : ObjectId("578e5cbd5b080fbfb7bed3d0"),    "post" : ObjectId("578df3efb618f5141202a196"),    "user_id" : ObjectId("578df3efb618f5141202a196"),    "__v" : 0}