Serverless-обработка CSV: импорт больших файлов по частям

export async function handler(event) {
  const { fileUrl, importId } = JSON.parse(event.body || '{}');
  if (!fileUrl || !importId) return { statusCode: 400, body: JSON.stringify({ error: 'fileUrl and importId required' }) };
  await db.imports.create({ id: importId, status: 'pending', fileUrl });
  await global.durable.startNew('process-csv', undefined, { fileUrl, importId });
  return { statusCode: 202, body: JSON.stringify({ importId, status: 'pending' }) };
}

import { parse } from 'csv-parse/sync';

export async function handler(event) {
  const { fileUrl, importId } = event; // the input passed to startNew()
  const csvText = await fetch(fileUrl).then((r) => r.text());
  const rows = parse(csvText, { columns: true, skip_empty_lines: true });
  let inserted = 0;
  for (const batch of chunk(rows, 500)) {
    // Upsert by external_id — idempotent on retry
    await db.records.upsertBatch(batch.map((r) => ({ ...r, importId })));
    inserted += batch.length;
  }
  await db.imports.update(importId, { status: 'done', rowCount: rows.length });
  return { importId, rows: rows.length, inserted };
}