🥑 ArangoDB: Adds the much needed `collection.bulkUpsert` function to ArangoJS. Uses a single query instead of multiple expensive roundtrips.

collection.bulkUpsert.ts

import { Database, DocumentCollection } from 'arangojs'
const db = new Database(process.env.ARANGODB_URL);
db.useDatabase('name');

/**
 * Upserts (merges) the content of the documents with the given documents and
 * optionally returns an array containing the documents’ metadata.
 *
 * @param {string|ArangoDB.Collection} collection - collection to use
 * @param {Document[]} documents - list of documents to upsert
 * @param opts? - optionally aggregate a result {inserted:number,updated:number}
 *  also see https://www.arangodb.com/docs/stable/aql/operations-upsert.html
 */
export async function bulkUpsert(
	collection: string | DocumentCollection,
	documents: Array<ArangoDB.DocumentData>,
	{ aggregate, ...upsertOptions }: {
		ignoreRevs?: boolean,
		exclusive?: boolean,
		aggregate?: boolean
	} = {}
): Promise<{inserted:number,updated:number} | true>
{
	return await (
		await db.query({
			query:  'FOR doc IN @documents'
			      + ' UPSERT { _key: doc._key } INSERT doc UPDATE MERGE(OLD, doc)'
			      + ' IN '+(typeof collection === 'string' ? collection : collection.name)
			      + ' OPTIONS '+JSON.stringify(upsertOptions)
			      + (aggregate ?
			        ' COLLECT AGGREGATE inserted = SUM(OLD ? 0 : 1), updated = SUM(OLD ? 1 : 0)'
			      + ' RETURN {inserted,updated}' :
			        ' RETURN true'),
			bindVars: {documents}
		})
	).next();
}