Mongoose array of objects query by slug - node.js

Question

I am trying to make a query for documents that have an array of objects like this. its a history of when a tag was added.
{
"added_by" : ObjectId("58d92d8b11af264b87a8f5d4"),
"tag" : ObjectId("58d92d8b11af264b87a8f5ed"),
"_id" : ObjectId("58d92d8c11af264b87a8f6d5"),
"added_at" : ISODate("2017-03-02T22:06:42.788Z")
}
I am not able to make the query on the slug just the _id
I have tried this:
var query = {
'tags.tag': {
slug: $in: ['tag-name']
}
}
Node.find(query, (err, nodes) => {
if (err) {
res.status(404)
res.send(err)
} else {
res.json(nodes);
}
}).populate(['tags.tag'])
Here is the document:
{
"_id" : ObjectId("58d92d8c11af264b87a8f6d0"),
"user_id" : ObjectId("58d92d8b11af264b87a8f5d4"),
"uid" : "-KeG2FvL0jwkHFvOautH",
"updated_at" : ISODate("2017-03-02T22:06:42.788Z"),
"created_at" : ISODate("2017-03-02T22:06:42.051Z"),
"tags" : [
{
"added_by" : ObjectId("58d92d8b11af264b87a8f5d4"),
"tag" : ObjectId("58d92d8b11af264b87a8f5ed"),
"_id" : ObjectId("58d92d8c11af264b87a8f6d5"),
"added_at" : ISODate("2017-03-02T22:06:42.788Z")
},
{
"added_by" : ObjectId("58d92d8b11af264b87a8f5d4"),
"tag" : ObjectId("58d92d8b11af264b87a8f626"),
"_id" : ObjectId("58d92d8c11af264b87a8f6d4"),
"added_at" : ISODate("2017-03-02T22:06:42.788Z")
}
],
"status" : "publish",
"description" : "some text here",
"title" : "Anna James",
"__v" : 0
}
Any thoughts?

Answer 1

Since you store references to tags, you need to fetch the tag by slug first:
TagsCollection.find({slug:'tag-name'}, (err, tags)...)
then filter by tag._id:
var query = {
'tags.tag': new ObjectId(tag._id)
}
or
var query = {
'tags.tag': {'$in": [new ObjectId(tag._id), ....]}
}
if you have more than 1 tag matching the slug.
Honestly, it would be way more efficient, if you store tags directly in the document, instead of storing references.