How to grab field value during a MongooseModel.bulkWrite operation? - node.js

Question

Context:
I am trying to upsert in bulk an array of data, with an additional computed field: 'status'.
Status should be either :
- 'New' for newly inserted docs;
- 'Removed' for docs present in DB, but inexistent in incoming dataset;
- a percentage explaining the evolution for the field price, comparing the value in DB to the one in incoming dataset.
Implementations:
data.model.ts
import { Document, model, Model, models, Schema } from 'mongoose';
import { IPertinentData } from './site.model';
const dataSchema: Schema = new Schema({
sourceId: { type: String, required: true },
name: { type: String, required: true },
price: { type: Number, required: true },
reference: { type: String, required: true },
lastModified: { type: Date, required: true },
status: { type: Schema.Types.Mixed, required: true }
});
export interface IData extends IPertinentData, Document {}
export const Data: Model<IData> = models.Data || model<IData>('Data', dataSchema);
data.service.ts
import { Data, IPertinentData } from '../models';
export class DataService {
static async test() {
// await Data.deleteMany({});
const data = [
{
sourceId: 'Y',
reference: `y0`,
name: 'y0',
price: 30
},
{
sourceId: 'Y',
reference: 'y1',
name: 'y1',
price: 30
}
];
return Data.bulkWrite(
data.map(function(d) {
let status = '';
// #ts-ignore
console.log('price', this);
// #ts-ignore
if (!this.price) status = 'New';
// #ts-ignore
else if (this.price !== d.price) {
// #ts-ignore
status = (d.price - this.price) / this.price;
}
return {
updateOne: {
filter: { sourceId: d.sourceId, reference: d.reference },
update: {
$set: {
// Set percentage value when current price is greater/lower than new price
// Set status to nothing when new and current prices match
status,
name: d.name,
price: d.price
},
$currentDate: {
lastModified: true
}
},
upsert: true
}
};
}
)
);
}
}
... then in my backend controller, i just call it with some route :
try {
const results = await DataService.test();
return new HttpResponseOK(results);
} catch (error) {
return new HttpResponseInternalServerError(error);
}
Problem:
I've tried lot of implementation syntaxes, but all failed either because of type casting, and unsupported syntax like the $ symbol, and restrictions due to the aggregation...
I feel like the above solution might be closest to a working scenario but i'm missing a way to grab the value of the price field BEFORE the actual computation of status and the replacement with updated value.
Here the value of this is undefined while it is supposed to point to current document.
Questions:
Am i using correct Mongoose way for a bulk update ?
if yes, how to get the field value ?
Environment:
NodeJS 13.x
Mongoose 5.8.1
MongoDB 4.2.1

Answer 1

EUREKA !
Finally found a working syntax, pfeeeew...
...
return Data.bulkWrite(
data.map(d => ({
updateOne: {
filter: { sourceId: d.sourceId, reference: d.reference },
update: [
{
$set: {
lastModified: Date.now(),
name: d.name,
status: {
$switch: {
branches: [
// Set status to 'New' for newly inserted docs
{
case: { $eq: [{ $type: '$price' }, 'missing'] },
then: 'New'
},
// Set percentage value when current price is greater/lower than new price
{
case: { $ne: ['$price', d.price] },
then: {
$divide: [{ $subtract: [d.price, '$price'] }, '$price']
}
}
],
// Set status to nothing when new and current prices match
default: ''
}
}
}
},
{
$set: { price: d.price }
}
],
upsert: true
}
}))
);
...
Explanations:
Several problems were blocking me :
the '$field_value_to_check' instead of this.field with undefined 'this' ...
the syntax with $ symbol seems to work only within an aggregation update, using update: [] even if there is only one single $set inside ...
the first condition used for the inserted docs in the upsert process needs to check for the existence of the field price. Only the syntax with BSON $type worked...
Hope it helps other devs in same scenario.