Duplicated entries in referenced array - MongoDB - Mongoose - node.js

Question

I'm new to MongoDb and I met this problem days ago and I can't resolve it. Basically, my user is allowed to create new Post with a bunch of Images. When I create the Post, then I create also the Images but when I check on mongo shell the entries in the array of the Post, one image can be present two or three times. (All the images are saved with an url)
These are my Models:
var postSchema = new mongoose.Schema({
Name: String,
Background: String,
Description: String,
posted: {type:Date,default: Date.now() },
images: [{type: mongoose.Schema.Types.ObjectId, ref: "image"}]
});
var imageSchema = new mongoose.Schema({
src: String,
caption: String
});
(These Schema are in separeted files and then exported as model)
This is my code for saving Post:
app.post("/post",isLoggedIn,function(req,res){
var post= {Name: req.body.name,
Background: req.body.backg,
Description: req.body.desc};
Posts.create(post, function(err, newPost){
if(err){
console.log(err);
} else {
var allImages = req.body.img;
allImages.forEach(function(singleImg){
Images.create(singleImg, function(err, newImg){
if(err){
console.log(err);
} else {
newPost.images.push(newImg);
newPost.save(function(err){
if(err){
return res.send(err);
}
});
}
});
});
}
});
return res.redirect("/posts");
});
Edit
This is my code with $addToSet
app.post("/post",isLoggedIn,function(req,res){
var post= {Name: req.body.name,
Background: req.body.backg,
Description: req.body.desc};
Posts.create(post, function(err, newPost){
if(err){
console.log(err);
} else {
Posts.findByIdAndUpdate(newPost._id, {$addToSet:{images: {$each: req.body.img}}}, function(err, updatedPost){
return res.redirect("/posts");
});
}
});
});
It gives me CastError Cast to ObjectId failed

Answer 1

Don't forget hanlde errors
Edit your code: (With Mongoose + nodejs - I suggest use indexOf, It runs very well with me, My DB have about 10M records)
From
Posts.create(post, function(err, newPost){
if(err){
console.log(err);
} else {
var allImages = req.body.img;
allImages.forEach(function(singleImg){
Images.create(singleImg, function(err, newImg){
if(err){
console.log(err);
} else {
newPost.images.push(newImg);
newPost.save(function(err){
if(err){
return res.send(err);
}
});
}
});
});
}
});
to
Posts.create(post, function(err, newPost){
if(err){
console.log(err);
} else {
var allImages = req.body.img;
allImages.forEach(function(singleImg){
Images.create(singleImg, function(err, newImg){
if(err){
console.log(err);
} else {
// Check exist
if (newPost.images.indexOf(newImg._id) == -1) {
newPost.images.push(newImg._id);
newPost.save(function(err){
if(err) {
return res.send(err);
}
});
} else {
console.log(newImg);
// do something
}
}
});
});
}
});
OR
Use $addToSet if you use MongoDb or Mongoose
Hope it will help you.
Thank you