Mongoose JS查询所有返回null或空 [英] Mongoose JS queries all coming back null or empty

问题描述

我正在尝试创建一个简单的MongooseJS示例程序，该程序从集合中获取项目列表，并且每次都会返回空白。以下是代码：

I am trying to create a simple MongooseJS example program that gets a list of items from a collection, and it's coming back empty every time. Here is the code:

var mongoose = require('mongoose')
  , Schema = mongoose.Schema;

var sampleSchema = new Schema({
    sampleField    : String
});

var db = mongoose.connect('mongodb://localhost:27017/test');

var sampleCollection = mongoose.model('sampleCollection', sampleSchema);

sampleCollection.find({ } , function (err, items) {
    console.log(items); // outputs []
    console.log(err); // outputs null
    items.forEach( function(item) {
        console.log(item); // does not reach this code
    });
});

我有一个默认的MongoDB运行实例，这就是我在shell中输入的内容：

I have a default instance of MongoDB running, and this is what I've entered in the shell:

> use test
> db.sampleCollection.save({sampleField : "Hello"});
> db.sampleCollection.save({sampleField : "Goodbye"});
> db.sampleCollection.find({});
{ "_id" : ObjectId("4f28944b38b59225012109da"), "sampleField" : "Hello" }
{ "_id" : ObjectId("4f28945138b59225012109db"), "sampleField" : "Goodbye" }

知道为什么我的代码没有返回任何数据吗？

Any idea why my code doesn't return any data?

感谢您的帮助，
Dave

Thanks for your help, Dave

推荐答案

mongoose 会将集合名称规范化为小写和复数。因此，您应该插入 db.samplecollections 而不是 db.sampleCollection 。 （注意字母 c 和 s 的区别）。

mongoose will normalize the name of collection to lowercase and pluralzed. Therefore, you should insert into db.samplecollections instead of db.sampleCollection. (Notice the difference of letter c and s here).

测试它：

s = new sampleCollection({sampleField: 'hello'}); // creates a new record
s.save(function(err) { 
  sampleCollection.find({ } , function (err, items) {
      console.log(items); 
      console.log(err); 
      items.forEach( function(item) {
          console.log(item); 
      });
  });
});

并正确打印：

[ { sampleField: 'hello', _id: 4f28ab4cc9e58f710a000001 } ]
null
{ sampleField: 'hello', _id: 4f28ab4cc9e58f710a000001 }

然后在mongo shell中：

then in mongo shell:

> show collections
samplecollections          //<<<<<<<<<<<<<< It's all lowercase and pluralized
system.indexes

> db.samplecollections.find()
{ "sampleField" : "hello", "_id" : ObjectId("4f28ab4cc9e58f710a000001") }

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