Mongoose doesn't save nested Object in another nested Object - node.js

Question

Usually in mongoose save the object nested, through the father's call method save, but if we have two levels of engagement, grandfather, father [nested], son [nested], the son is not saved through the father's call method save.
Grandfather -> Group
var schema = new mongoose.Schema({
name: String,
days:[mongoose.Schema.Types.Day],
});
module.exports = mongoose.model('Group', schema);
Father -> Day
var schema = new mongoose.Schema({
_id: Number,
matches:[mongoose.Schema.Types.Match]
});
module.exports = mongoose.model('Day', schema);
Son -> Match
var schema = new mongoose.Schema({
team1: {
type: Schema.ObjectId,
ref:'Team'
},
team2: {
type: Schema.ObjectId,
ref: 'Team'
},
score: [Number]
});
module.exports = mongoose.model('Match', schema);
In the routes ("matches.js") I try to save the group jointly day and match.
Group.findById(groupId).exec(
function(err, group){
var match = new Match();
var day = group.days[dayNumber-1];
day.matches.push(
match
);
group.save(function(err){
console.log("success");
console.log("group in matches.js:"+group);
res.redirect("/tournaments/"+tournamentId+"/groups/"+groupId+"/days/"+dayNumber);
});
});
In the redirect I print again the "group" and the match disappears.
app.get('/tournaments/:tournamentId/groups/:groupId/days/:dayNumber', function (req, res) {
groupId = req.params.groupId;
dayNumber = req.params.dayNumber;
Group.findById(groupId, function (err, group) {
console.log("group in days.js:"+group);
res.render('days/show', {
title: 'Days',
group: group,
day:group.days[dayNumber-1],
tournamentId: req.params.tournamentId
});
});
});
The console log print:
new match
success
group in matches.js:{ __v: 7,
_id: 53a3ee54dfe793bd9a20c6ab,
name: 'gruppo sdirubbo',
days: [ { matches: [Object], _id: 1 } ] }
GET /tournaments/539f0185ea17e46e73be937b/groups/53a3ee54dfe793bd9a20c6ab/days/1/newMatch 302 4ms - 208b
group in days.js:{ __v: 7,
_id: 53a3ee54dfe793bd9a20c6ab,
name: 'gruppo sdirubbo',
days: [ { matches: [], _id: 1 } ] }

Answer 1

mongoose.Schema.Types.Day and mongoose.Schema.Types.Match are undefined so those array fields that reference them are ending up as Mixed types instead which don't save unless you explicitly mark them modified.
You need to make those schemas available between the model definitions and then use those in your definitions instead. For example:
var matchSchema = new mongoose.Schema({
team1: {
type: Schema.ObjectId,
ref:'Team'
},
team2: {
type: Schema.ObjectId,
ref: 'Team'
},
score: [Number]
});
var daySchema = new mongoose.Schema({
_id: Number,
matches:[matchSchema]
});
var groupSchema = new mongoose.Schema({
name: String,
days:[daySchema],
});