Express: mongodb mongoose linking entities - node.js

Question

I'm building a simple web app where a company sends out a question to its employees requesting for feedback. Still learning about mongodb. Been playing around with it all week & I'm slowly getting a good hang of it with some helpful assistance on the forums but only now I realize I have been using a flawed thought process to design the schema. I was initially using a user's response as a field in the UserSchema but I have now removed it (as commented out here) as I realized this is not a user's property but rather a variable that keeps changing (yes/no/null). I now have to create a separate AnswersSchema (I was told I'll need one but I stubbornly argued against it - saw no sense in at the time I started the project) which I have done now (correct me if it's wrongly written/thought out). My question now is how do I modify my query in the api to link all the three entities together on a save operation in the router post? Please note the save operation code shown here works but is flawed as it's for when the user has a response as one of their properties. So now only the user's name shows up on the angular front-end after I removed response on UserSchema which makes sense.
var QuestionSchema = Schema({
id : ObjectId,
title : String,
employees : [{ type: ObjectId, ref: 'User'}]
});
var UserSchema = Schema({
username : String,
//response : String,
questions : [{ type: ObjectId, ref: 'Question'}]
});
//new schema/collection I've had to create
var AnswerSchema = Schema({
response : {type :String, default:null},
question : { type: ObjectId, ref: 'Question'},
employees : [{ type: ObjectId, ref: 'User'}],
})
module.exports = mongoose.model('Question', QuestionSchema);
module.exports = mongoose.model('User', UserSchema);
module.exports = mongoose.model('Answer', AnswersSchema);
api.js
Question.findOne({ title: 'Should we buy a coffee machine?'}).exec(function(err, question) {
//example data
var user = new User([{
"username": "lindelof",
"response": "yes",
},{
"username": "bailly",
"response": "no",
},{
"username": "suzan",
"response": "yes",
}]);
question.employees = [user1._id];
user.questions = [question._id];
question.save(function(err) {
if (err) throw err;
console.log(question);
user1.save(function(err) {
if (err) throw err;
});
});
});
console.log('entry saved >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>');
}
UPDATE

Answer 1

You did the right thing by adding AnswerSchema, as it's a many to many relationship. A question can be answered by many users (employees). A user can answer many questions. Therefore, it's good to have answer as an associative collection between the two.
With this relationship in mind, you need to change your schema a little:
var QuestionSchema = Schema({
id : ObjectId,
title : String,
//employees : [{ type: ObjectId, ref: 'User'}]
});
var UserSchema = Schema({
username : String,
//response : String,
//questions : [{ type: ObjectId, ref: 'Question'}]
});
var AnswerSchema = Schema({
response : {type :String, default:null},
question : { type: ObjectId, ref: 'Question'},
employee : { type: ObjectId, ref: 'User'}, //a single employee
});
Now, to know if a certain user has answered a question already, just search Answer with his and the question's ids:
Answer.findOne({
question: questionId,
employee: userId
})
.exec(function(err, answer) {
if (err) {
} else if (!answer) {
//the employee has not answered this question yet
} else {
//answered
}
});
Lastly, your submit-answer API should expect a body that contains questionId and userId (if signed in, you can get userId from session or token also). This route updates existing answer, else creates it (for create-only use create function)
router.post('/', function(req, res) {
//req.body = {question: "594315b47ab6ecc30d5184f7", employee: "594315d82ee110d10d407f93", response: "yes"}
Answer.findOneAndUpdate({
question: req.body.question,
employee: req.body.user
},
req.body,
{
upsert: true //updates if present, else inserts
}
})
.exec(function(err, answer) {
//...
});
});