Mongoose one-to-many

问题:

can you explain me how to organize mongoose models to create one to many connections? It is needed keep separate collections.

suppose i have stores and items

//store.js

var mongoose = require('mongoose');

module.exports = mongoose.model('Store', {
    name : String,
    itemsinstore: [ String]
});

//item.js

var mongoose = require('mongoose');
module.exports = mongoose.model('Item', {
    name : String,
    storeforitem: [String]
 });

Am i doing it in the right way?

And how to access pass data to arryas? Here is the code yo enter name to item. But how to enter id to array of id's (itemsinstore)?

app.post('/api/stores', function(req, res) {
    Store.create({
        name: req.body.name,
    }, function(err, store) {
        if (err)
            res.send(err);
    });
})

回答1:

You should use model reference and populate() method: http://mongoosejs.com/docs/populate.html

Define your models:

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

var storeSchema = Schema({
   name : String,
   itemsInStore: [{ type: Schema.Types.ObjectId, ref: 'Item' }]
});
var Store = mongoose.model('Store', storeSchema);

var itemSchema = Schema({
    name : String,
    storeForItem: [{ type: Schema.Types.ObjectId, ref: 'Store' }]
});
var Item = mongoose.model('Item', itemSchema);

Save a new item into an existing store:

var item = new Item({name: 'Foo'});
item.save(function(err) {

  store.itemsInStore.push(item);
  store.save(function(err) {
    // todo
  });
});

Get items from a store

Store
  .find({}) // all
  .populate('itemsInStore')
  .exec(function (err, stores) {
    if (err) return handleError(err);

    // Stores with items
});

回答2:

Okay, this is how you define a dependancy:

var mongoose = require('mongoose');

module.exports = mongoose.model('Todo', {
    name : String,
    itemsinstore: [{ type: Schema.Types.ObjectId, ref: 'Item' }]
});

And make sure you have different names:

var mongoose = require('mongoose');
module.exports = mongoose.model('Item', {
    name : String,
    storeforitem: [String]
 });

Keep an eye on Item in both cases.

And then you just want to pass the array of ObjectIDs in it. See more here: http://mongoosejs.com/docs/populate.html

回答3:

You can do using the best practices with Virtuals.

Store.js

const mongoose = require('mongoose')
const Schema = mongoose.Schema

const StoreSchema = new Schema({
    name: {
        type: String,
        required: true
    },
    createdAt: {
        type: Date,
        default: Date.now
    }
})

StoreSchema.virtual('items', {
    ref: 'Item',
    localField: '_id',
    foreignField: 'storeId',
    justOne: false // set true for one-to-one relationship
})

module.exports = mongoose.model('Store', StoreSchema)

Item.js

const mongoose = require('mongoose')
const Schema = mongoose.Schema

const ItemSchema = new Schema({
    storeId: {
        type: Schema.Types.ObjectId,
        required: true
    },
    name: {
        type: String,
        required: true
    },
    createdAt: {
        type: Date,
        default: Date.now
    }
})

module.exports = mongoose.model('Item', ItemSchema)

StoreController.js

const Store = require('Store.js')

module.exports.getStore = (req, res) => {
    const query = Store.findById(req.params.id).populate('items')

    query.exec((err, store) => {
        return res.status(200).json({ store, items: store.items })
    })
}

Keep in mind that virtuals are not included in toJSON() output by default. If you want populate virtuals to show up when using functions that rely on JSON.stringify(), like Express' res.json() function, set the virtuals: true option on your schema's toJSON options.

// Set `virtuals: true` so `res.json()` works
const StoreSchema = new Schema({
    name: String
}, { toJSON: { virtuals: true } });

回答4:

Try this:

 Store.findOne({_id:'5892b603986f7a419c1add07'})
  .exec (function(err, store){
    if(err) return res.send(err);

   var item = new Item({name: 'Foo'});
   item.save(function(err) {

   store.itemsInStore.push(item);
   store.save(function(err) {
    // todo
 });
});