two way navigation in a mongo one to n relashionship - node.js

Question

I'm having hard times with the mongoose relashionship system.
Here are my schemes:
const mongoose = require('mongoose');
const RecipeSchema = mongoose.Schema({
Title: { type: String },
Description: { type: String },
Complaints: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Complaint' }]
});
const Recipe = mongoose.model('Recipe', RecipeSchema);
const ComplaintSchema = mongoose.Schema({
Recipe : { type: mongoose.Schema.Types.ObjectId, ref: 'Recipe' },
Message: { type: String }
});
const Complaint = mongoose.model('Complaint', ComplaintSchema);
And here are how I'm saving my data:
var recipeEntity = new Recipe({
Title: request.body.Title,
Description: request.body.Description
});
recipeEntity.save();
var complaintEntity= new Complaint({
Message: request.body.Message.trim(),
Recipe: mongoose.Types.ObjectId(request.body.Message.RecipeId);
});
complaintEntity.save();
So far, so good... at least to me!
And now, when I try to list the recipes with the complaints, I just got an empty array of complaints:
Recipe
.find()
.populate('Complaints')
.exec(callback);
And here is the json result:
[{
"Id": "595fe6f89d63700011ee144d",
"Title": "Chocolate Cake",
"Description": "aaaa bbb cc d"
"Complaints": []
}]
So, what am I missing here?
tks for your support

Answer 1

I am going to assume that you are not saving both recipe and complaint during the same call. That would not make any sense: everytime you make a complaint, you wouldn't make a recipe too.
When you create a complaint, you need to save its associated recipe's ObjectId AND also add/push the complaint's ObjectId into the associated recipe's complaints.
If you are following resource naming conventions, you would have something like:
// get recipes including complaints
app.get('/recipes', function (req, res) {
Recipe.find().populate('Complaints').exec(function (err, recipes) {
console.log(recipes);
});
});
// add recipe
app.post('/recipes', function (req, res) {
var recipe = new Recipe(req.body); // simplified
recipe.save(function (err) {
if (err)
return res.send(err);
res.send('ok');
});
});
// add complaint for recipe
app.post('/recipes/:recipeID/complaints', function (req, res) {
// we query recipe bc we need it after
Recipe.findById(req.params.recipeID, function (err, recipe) {
if (err)
return res.send(err);
if (!recipe)
return res.send('No recipe found');
// add complaint
var complaint = new Complaint(req.body);
complaint.Recipe = recipe._id; // add reference in one direction
complaint.save(function (err) {
if (err)
return res.send(err);
// update recipe
recipe.Complaints.push(complaint._id); // add reference in other direction
recipe.save(function (err) {
if (err)
return res.send(err);
res.send('ok');
});
});
});
})
I think this is a good read: many to many relationship with nosql (mongodb and mongoose).

Answer 2

OK, how I had to save the record in the reference too, I adopted this approach:
RecipeSchema.pre('remove', function(next) {
Complaint.remove({ "Recipe" : this._id }).exec();
next();
});
ComplaintSchema.pre('remove', function(next) {
Recipe.findById(this.Recipe).exec((error, item) => {
var index = item.Complaints.indexOf(item.Complaints.find(e => e._id == this._id));
item.Complaints.splice(index, 1);
item.save(() => { next(); });
});
});
ComplaintSchema.pre('save', function(next) {
Recipe.findById(this.Recipe).exec((error, item) => {
item.Complaints.push(this);
item.save(() => { next(); });
});
});
using this trigger/event available on the mongo schemas.
That worked perfectly!