Submit a Zoho CRM v8 bulk write job to upsert large datasets via the API

Steps

1. Authenticate using Zoho's OAuth 2.0 flow and obtain an access token scoped to ZohoCRM.bulk.ALL or ZohoCRM.bulk.CREATE + ZohoCRM.bulk.UPDATE for the relevant operations
2. Create a bulk write job via POST to the Zoho CRM v8 bulk write endpoint specifying the module (e.g., Leads, Contacts), operation (insert, update, or upsert), and the field used as the duplicate check key for upsert operations
3. Upload the data as a CSV or JSON file to the job's upload endpoint, then call the job execute endpoint to trigger processing
4. Poll the job status endpoint using the returned job ID until status is COMPLETED or FAILED — the job processes asynchronously and large files may take several minutes
5. On COMPLETED, fetch the result summary which reports total records processed, successful, and failed counts; download the failed-record file if failures are reported
6. Parse failed records to identify field-validation errors, duplicate conflicts, or missing required fields, then correct and resubmit a remediated file in a new job