How to delete in cascade in several models with mongoose? - mongodb

Question

I have these 3 models in mongoose:
TravelSchema
var travelSchema = new mongoose.Schema({
name: String,
description: String,
mexican_currency_value: mongoose.Schema.Types.Decimal128
})
travelSchema.pre('deleteOne', function(next) {
const id = this.getQuery()['_id'];
Product.deleteMany({ travel: id }, (err, value) => {
});
next();
});
ProductSchema
var productSchema = new mongoose.Schema({
name: String,
description: String,
purchased_amount: Number,
unit_price_mex: mongoose.Schema.Types.Decimal128,
unit_price_to_sell: mongoose.Schema.Types.Decimal128,
travel: { type: mongoose.Schema.Types.ObjectId, ref: 'Travel' }
})
InvoiceSchema
var invoiceSchema = new mongoose.Schema({
product: productSchema,
client: { type: mongoose.Schema.Types.ObjectId, ref: 'Client' },
purchased_amount: Number,
fch: String
});
Where Travel and Product have a one-to-many relationship and Product and Invoice have a one-to-many relationship.
I need the following:
When a Travel is deleted, all Products that are related to that Travel are also deleted.
When these Products are eliminated, all the Invoices related to each Product are also eliminated.
I have managed to eliminate all the products, but when I try to eliminate the invoices I do not obtain the ids of the Products.
invoiceSchema.pre('deleteMany', (next) => {
console.log(this);
// this print { n: 2, ok: 1, deletedCount: 2 }
})

Answer 1

I think you should start the other way when looking at deleting all the related docs. Like you have travel id, with it get all the products and store their id in array and then your first delete should be of the invoices where product._id: { $ in: _arrayOfProducIds }. Once that is complete then deleteMany your products since you already have their ids in the _arrayOfProducIds and lastly deal with the Travel:
travelSchema.pre('deleteOne', function(next) {
const id = this.getQuery()['_id']; // travel id check
// Query to get all the product ids based on the travel id and return array for `$in`
const productIds = this.DoYourQuery // [productIds] check
Invoice.deleteMany({'product._id': { $in: productIds }}, // ... etc
Product.deleteMany({ _id': { $in: productIds }}, // ... etc
next();
});
I would assume you do not have a large number of products and invoices ... like thousands since then $in might be somewhat of a performance issue. Hope this helps.