[BUG] Expecting error in bulk upserts

[bentcoder]

What is the bug?

To be fair I am not sure if this is a bug or an intentional design choice.

When I insert many docs in one go using Bulk Request API, there is no way of knowing how many docs have failed due to bad data they contain. For instance, if you insert a single doc (I know it is a bad doc) using non-bulk operation, you will get 400 error telling you what the problem was. However, bulk API carries on without an error.

How can one reproduce the bug?

// github.com/opensearch-project/opensearch-go/v4/opensearchapi
// Client: *opensearchapi.Client
func (o Opensearch) UpsertOffers(ctx context.Context, offers []*document.Offer) error {
	var body strings.Builder

	for _, offer := range offers {
		body.WriteString(fmt.Sprintf(`{"update":{"_id":"%s","_index":"%s"}}`, offer.Path, "my_index"))
		body.WriteString("\n")

		doc, err := json.Marshal(map[string]any{"doc": offer, "doc_as_upsert": true})
		if err != nil {
			return err
		}

		body.Write(doc)
		body.WriteString("\n")
	}

	req := opensearchapi.BulkReq{
		Body: strings.NewReader(body.String()),
	}

	res, err := o.Client.Client.Do(ctx, req, nil)
	if err != nil {
		return err
	}
	defer res.Body.Close()

	if res.IsError() {
		return fmt.Errorf("unexpected response: %s - %s", res.Status(), res.String())
	}

	return nil
}

What is the expected behavior?

At least res.IsError() or something could list failed docs.

[dblock]

Does the server side API return the numbers and info?

[bentcoder]

Actually the response body reports if there is an error but looks like I have to iterate objects one by one in order to extract errors which will probably be very costly.

{
  "took": 2,
  "errors": false,
  "items": [
        {
            "update": {
                "_index": "offers_20250122",
                "_id": "BV",
                "status": 400,
                "error": {
                    "type": "mapper_parsing_exception",
                    "reason": "failed to parse field [data.value] of type [long] in document with id 'BV'. Preview of field's value: '5,690'",
                    "caused_by": {
                        "type": "illegal_argument_exception",
                        "reason": "For input string: \"5,690\""
                    }
                }
            }
        },
        {
            "update": {
                "_index": "offers_20250122",
                "_id": "OA3",
                "_version": 13,
                "result": "noop",
                "_shards": {
                    "total": 2,
                    "successful": 1,
                    "failed": 0
                },
                "_seq_no": 226007,
                "_primary_term": 1,
                "status": 200
            }
        }
  ]
}