Save multiples Objects At Once Mongo(Many To Many Mongoose) - node.js

Question

this is my scene:
I have 2 collections(tables):Projects and students(the relation is many to many).
My models are:
Project:
var ProjectSchema = new Schema({
name: {
type: String
},
description: {
type: String
},
user : {
type : Mongoose.Schema.Types.ObjectId,
ref : "User"
}
});
Mongoose.model('Project', ProjectSchema);
User:
var Userchema = new Schema({
name: {
type: String
},
surname: {
type: String
},
project : {
type : Mongoose.Schema.Types.ObjectId,
ref : "Project"
}
});
Mongoose.model('User', UserSchema);
In my view I have 2 inputs where receive name and description of project, then have multiselect where choose 1 or multiples users for this project. When I Click OK should:
Create project, and add to user all users selected as objects in BBDD.
Update user, with project asociation.
I try the next, but only funcion if I choose 1 user:
exports.addUserProject = function(req, res) {
var project=new svmp.Project();
project.name=req.body.name;
project.description=req.body.description;
project.user=req.body.user[0]._id;
project.save(function(err,project){
if (err) {
return res.send(400, {
message : getErrorMessage(err)
});
} else {
res.jsonp(project);
}
})
};
The result in my BBDD is the next:
{ "_id" : ObjectId("57a200a38fae140913ac5413"), "user" : ObjectId("578f41ddb0641d961416c3f5"), "name" : "Project1", "Description" : "Project1 Desc","__v" : 0 }
Thanks for your help

Answer 1

First in your schema definition, since the relationship is many-to-many, you should change the ref to an array of the referenced objects. For example change the user property of projectSchema to an array of object ids like so,
var ProjectSchema = new Schema({
name: {
type: String
},
description: {
type: String
},
user : [{
type : Mongoose.Schema.Types.ObjectId,
ref : "User"
}]
});
Do the same for the project property of the userSchema.
Secondly, on this line project.user=req.body.user[0]._id; you are setting the the _id of only the first selected user as the user while ignoring every other selected users. This is why your code only works for one user. Instead, I will suggest you use a simple loop to push all selected users' _id to the project's user property. You can use a forEach loop as given below.
var selectedUsers = req.body.user;
selectedUsers.forEach(function(u){
project.user.push(u._id)
})
You can also do this with a simple for loop if you wish.
I believe the suggestions above should fix the issues you described.