Function processBeforeSend

packages/core/src/client.ts:1646–1744

* Process the matching `beforeSendXXX` callback.

(
  client: Client,
  options: ClientOptions,
  event: Event,
  hint: EventHint,
)

 * Process the matching `beforeSendXXX` callback.
 */
function processBeforeSend(
  client: Client,
  options: ClientOptions,
  event: Event,
  hint: EventHint,
): PromiseLike<Event | null> | Event | null {
  const { beforeSend, beforeSendTransaction, ignoreSpans } = options;
  const beforeSendSpan = !isStreamedBeforeSendSpanCallback(options.beforeSendSpan) && options.beforeSendSpan;

  let processedEvent = event;

  if (isErrorEvent(processedEvent) && beforeSend) {
    return beforeSend(processedEvent, hint);
  }

  if (isTransactionEvent(processedEvent)) {
    // Avoid processing if we don't have to
    if (beforeSendSpan || ignoreSpans) {
      // 1. Process root span
      const rootSpanJson = convertTransactionEventToSpanJson(processedEvent);

      // 1.1 If the root span should be ignored, drop the whole transaction
      if (
        ignoreSpans?.length &&
        shouldIgnoreSpan(
          { description: rootSpanJson.description, op: rootSpanJson.op, attributes: rootSpanJson.data },
          ignoreSpans,
        )
      ) {
        // dropping the whole transaction!
        return null;
      }

      // 1.2 If a `beforeSendSpan` callback is defined, process the root span
      if (beforeSendSpan) {
        const processedRootSpanJson = beforeSendSpan(rootSpanJson);
        if (!processedRootSpanJson) {
          showSpanDropWarning();
        } else {
          // update event with processed root span values
          processedEvent = merge(event, convertSpanJsonToTransactionEvent(processedRootSpanJson));
        }
      }

      // 2. Process child spans
      if (processedEvent.spans) {
        const processedSpans: SpanJSON[] = [];

        const initialSpans = processedEvent.spans;

        for (const span of initialSpans) {
          // 2.a If the child span should be ignored, reparent it to the root span
          if (
            ignoreSpans?.length &&
            shouldIgnoreSpan({ description: span.description, op: span.op, attributes: span.data }, ignoreSpans)
          ) {
            reparentChildSpans(initialSpans, span);
            continue;