为什么我的小猫在从数据库中取出时不能说话？

遵循http://mongoosejs.com/docs/index.html上的指南，我很明显的误解了一些基本的东西。 为什么shema不适用于我检索的对象？

代码

mongoose = require('mongoose'); mongoose.connect('mongodb://localhost/local'); db = mongoose.connection; db.on('error', console.error.bind(console, 'connection error:')); db.once('open', function callback() { // yay! }); var kittySchema = mongoose.Schema({ name: String }) kittySchema.methods.speak = function () { var greeting = this.name ? "Meow name is " + this.name : "I don't have a name" console.log(greeting); } var Kitten = mongoose.model('Kitten', kittySchema) var silence = new Kitten({ name: 'Silence' }) var fluffy = new Kitten({ name: 'fluffy' }); silence.save(function (err, silence) { if (err) // TODO handle the error console.log(err.message); else silence.speak(); }); fluffy.save(function (err, fluffy) { if (err) // TODO handle the error console.log(err.message); else fluffy.speak(); }); Kitten.find(function (err, kittens) { if (err) // TODO handle err console.log(kittens) else { for (var kitten in kittens) { kitten.speak(); } } }); 

输出

 Path\TestEx\node_modules\mongoose\lib\utils.js:413 throw err; ^ TypeError: Object 0 has no method 'speak' at Promise.<anonymous> (Path\TestEx\app.js:66:20) at Promise.<anonymous> (Path\TestEx\node_modules\mongoose\node_modules\mpromise\lib\promise.js:162:8) at Promise.EventEmitter.emit (events.js:95:17) at Promise.emit (Path\TestEx\node_modules\mongoose\node_modules\mpromise\lib\promise.js:79:38) at Promise.fulfill (Path\TestEx\node_modules\mongoose\node_modules\mpromise\lib\promise.js:92:20) at C:\Users\Richard\WebstormProjects\TestEx\node_modules\mongoose\lib\query.js:1716:26 at model.Document.init (Path\TestEx\node_modules\mongoose\lib\document.js:243:11) at completeMany (Path\TestEx\node_modules\mongoose\lib\query.js:1714:12) at cb (Path\TestEx\node_modules\mongoose\lib\query.js:1677:11) at Path\TestEx\node_modules\mongoose\lib\utils.js:408:16 

Answer 1

你的JavaScript有错误。 检查文档for for ... in循环 。 它遍历一个对象的字段，而不是一个数组。 所以，而不是for ... in循环中，你应该使用一个普通for循环迭代器 ：

 for (var i = 0; i < kittens.length; i++) { kittens[i].speak(); }