Delete all occurrences of ObjectId in arrays - node.js

Question

I have the following schema:
var userSchema = new mongoose.Schema({
username: {type: String, required: true},
favouriteItems: [{type: mongoose.Schema.Types.ObjectId, ref: 'Item'}],
userItems: [{type: mongoose.Schema.Types.ObjectId, ref: 'Item'}]
});
var itemSchema = new mongoose.Schema({
name: {type: String, required: true},
price: {type: Number, required: true}
});
mongoose.model('User', userSchema , 'Users');
mongoose.model('Item', itemSchema , 'Items');
When I delete the item, I want to remove its ObjectId from favouriteItems and userItems from all users whose array contains it.
Example:
Initial:
Users:
[
{
_id: "a",
username: "username1",
favouriteItems: ["id1"],
userItems: ["id2", "id3"]
},
{
_id: "b",
username: "username2",
favouriteItems: ["id2"],
userItems: ["id1", "id4"]
},
...
]
Items:
[
{
_id: "id1",
name: "item1",
price: 19
},
{
_id: "id2",
name: "item2",
price: 7
},
...
]
When I remove item with id id1 I want the following result (id1 must be removed from arrays favouriteItems and userItems of all users):
Users:
[
{
_id: "a",
username: "username1",
favouriteItems: [],
userItems: ["id2", "id3"]
},
{
_id: "b",
username: "username2",
favouriteItems: ["id2"],
userItems: ["id4"]
},
...
]
Items:
[
{
_id: "id2",
name: "item2",
price: 7
},
...
]
How do I achieve this using mongoose and node.js?

Answer 1

You should take a look at the post mongoose middleware hooks and specifically the hook on remove:
itemSchema.post('remove', async function(doc) {
// doc is removed ... execute query to remove from favorites using the `doc._id`
});