how do I populate a document mongoose or save refs - node.js

Question

I have a questions collection and I have a store model. I want the questions field in the Store model to be to be the array of object ids from the questions collection. so I could use populate later. when I do app.get in the future it should show me a doc with the store info and all the questions.
var Schema = mongoose.Schema;
var storeSchema = Schema({
name : {type : String},
industry : {type : String},
questions :[{type : Schema.Types.ObjectId, ref : "Questions" }]
})
var questionsSchema = Schema({
question : {type :String}
})
var store = mongoose.model("Store", storeSchema);
var questions = mongoose.model("Questions", questionsSchema)
// questions.create({question: "question2"}, function(err,q){
// console.log("create: " , q)
// })
//something like this
questions.find({}, function(err, doc){
store.create({name : "store 1", industry : "industry 1" , questions : /*get the _ids from the question collection*/ {$push : doc.question}})
})
> db.questions.find().pretty()
{
"_id" : ObjectId("574534a289763c004643fa08"),
"question" : "question1",
"__v" : 0
}
{
"_id" : ObjectId("574534acc90f3f2c0c3d529b"),
"question" : "question2",
"__v" : 0
}
>

Answer 1

Population is the process of automatically replacing the specified paths in the document with document(s) from other collection(s). We may populate a single document, multiple documents, plain object, multiple plain objects, or all objects returned from a query.
var question = new Questions();
question.save(function(err) {
var store = new Store({
name:'sample',
industry:'tech',
questions: [question._id],
});
store.save(function(err){
//do whatever you would like, post creation of store.
});
});
Store.find(...).exec(function(err, stores) {
Questions.populate(stores, function(err, storesPostPopulate) {
// Now you have Stores populated with all the questions.
})
});
Since questions field in question schema is an array, you can always push another question id to it.
See mongoose populate
See mongoose Model populate