javascript - 如何让 Mongoose 列出集合中的所有文档？判断集合是否为空？

Question

我正在使用 MEAN 堆栈并在 Mongoose 中编写这些方法。我想知道我放入 Mongoose 模型文件中的内容有什么问题。我想使用 Mongoose 简单地打印出 myModel 集合中所有文档的列表。

myModel.methods.myMethod = function(cb){
  this.model("Bids").find({}, 'myField', function(err, results){
    if (err){console.log(err);return err;}
    console.log("okay");
    console.log(results);
  })
  this.save(cb);
}

另外，我可以用 Mongoose 编写什么代码来判断 myModel 集合是否为空？

---

授人以鱼不如授人以渔...

因此，如果您能建议我可以安装哪些调试工具(例如 Express 中间件)来帮助我 self 调试，那将非常有帮助。 Please post your debugging suggestions here .

Answer 1

我假设 mongoose 所需的所有其他设置都是正确的。

在下面的行中，我认为不需要“myField”。

  this.model("Bids").find({}, 'myField', function(err, results)

这里有一些从头开始的东西，也许它会帮助你追溯你的步骤:

 var mongoose = require('mongoose');

    //connection to Mongodb instance running on=======
    //local machine or anywhere=========================
    var uri = 'mongodb://localhost:27017/test';
    var connection = mongoose.createConnection(uri);


    //Define Schema==================================
    var Schema = mongoose.Schema;
    var BlogPostSchema = new Schema({
      author: { type: Schema.Types.ObjectId },
      title: String,
      body: String
    });


    //Create model===================================================
    var BlogPostModel = connection.model('BlogPost', BlogPostSchema);


    //function to insert doc into model NOTE "pass in your =======
    //callback or do away with it if you don't need one"=========
    var insertBlogPost = function (doc, callback) {
      
      //here is where or doc is converted to mongoose object
      var newblogPost = new BlogPostModel(doc); 
      
      //save to db
      newblogPost.save(function (err) {

        assert.equal(null, err);
        
        //invoke your call back if any
        callback();
        console.log("saved successfully");
      });
    };


    //function to get all BlogPosts====================================
    var getAllBlogPosts = function (callback) {

    //mongoose get all docs. I think here answers your question directly
      BlogPostModel.find(function (err, results) {
        assert.equal(null, err);
        
        //invoke callback with your mongoose returned result
        callback(results);
      });
    };


    //you can add as many functions as you need.

    //Put all of your methods in a single object interface 
    //and expose this object using module.

    var BlogPostManager = {
        insertBlogPost: insertBlogPost,
        getAllBlogPosts : getAllBlogPosts
    }


    module.exports = BlogPostManager;