Loopback - How to use bulkUpdate method - rest

Question

I'm using Loopback v3 currently and wanted to upsert many records at once in a collection; I found this method bulkUpsert from the documentation (http://apidocs.loopback.io/loopback/#persistedmodel-bulkupdate) but I couldn't figure out how to make it work.
How can I create the updates array from createUpdates() method as mentioned in the documentation? Can anyone help me with a simple example of using this method?

Answer 1

There is an alternative way to do the bulkUpdate method, found in Stackoverflow MongoDB aggregation on Loopback
A mixin can be easily created and reused over the Models. My sample code of bulkUpsert mixin is below:
Model.bulkUpsert = function(body, cb) {
try {
Model.getDataSource().connector.connect(async (err, db) => {
if (err) {
return cb(err);
}
// Define variable to hold the description of the first set of validation errors found
let validationErrors = '';
// Build array of updateOne objects used for MongoDB connector's bulkWrite method
const updateOneArray = [];
// Loop through all body content and stop the loop if a validation error is found
const hasError = body.some(row => {
// Check if it is a valid model instance
const instance = new Model(row);
if (!instance.isValid()) {
// A validation error has been found
validationErrors = JSON.stringify(instance.errors);
// By returning true we stop/break the loop
return true;
}
// Remove ID in the row
const data = JSON.stringify(row);
delete data.id;
// Push into the update array
updateOneArray.push({
updateOne: {
filter: { _id: row.id },
update: { $set: Object.assign({ _id: row.id }, data) },
upsert: true
}
});
// No validation error found
return false;
});
// Check if a validation error was found while looping through the body content
if (hasError) {
return cb(new Error(validationErrors));
}
// No validation data error was found
// Get database collection for model
const collection = db.collection(Model.name);
// Execute Bulk operation
return collection.bulkWrite(updateOneArray, {}, (err, res) => {
// Check if the process failed
if (err) {
console.err('The bulk upsert finished unsuccessfully', err);
return cb(err);
}
// Check if there were errors updating any record
if (res.hasWriteErrors()) {
console.error(`The bulk upsert had ${res.getWriteErrorCount()} errors`, res.getWriteErrors());
}
// Finished successfully, return result
return cb(null, {
received: body.length,
handled: res.upsertedCount + res.insertedCount + res.matchedCount
});
});
});
}
catch (err) {
console.error('A critical error occurred while doing bulk upsert', err);
return cb(err);
}
return null;
};
Ref: Mongodb query documentation