插入猫鼬集合并导出模型

Question

I'm having trouble understanding mongoose and exporting in node/express.

I have this model.js file

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

var UserSchema = new Schema({
  name: String
});

var User = mongoose.model("User", UserSchema);

if (User.count() == 0) {
    User.insert({name: 'john doe'})
};

module.exports = User;

And I want to export this var User so that I can use it later to insert new users in my app.post routes in my app.js.

var User = require("User")

But it says the module User is undefinded or something similar.

Answer 1

As long as your model.js file is required before you intend to use the model you can use Mongoose's internal model cache to retrieve a model in any other file.

main_file.js

var mongoose = require('mongoose');
require('./model.js') // loads models
// Only need to load them once for entire project

var User = mongoose.model('User'); // Notice no schema provided
// You can do this in any other file as long as
// they are required after the models are loaded

Sidenote: count is an async operation so your conditional check is not working as you intended.

Answer 2

I am assuming model.js is the name of your file.

You need to include the path to the model.js. For example, if I had model.js in a folder called models in my projects root directory, then I would do this:

var User = require("./models/model")

When you use require() npm assumes you are either talking about one of the core modules or one of the npmjs packages in the ./node_modules directory. If it is not a core module or located in node_modules, then node won't know where to find it--unless you give it the full path. This blog post explains it nicely:

http://www.bennadel.com/blog/2169-where-does-node-js-and-require-look-for-modules.htm