Function refreshSignalQuery

packages/core/src/render3/queries/query_reactive.ts:111–146

(node: QuerySignalNode<V>, firstOnly: boolean)

}

function refreshSignalQuery<V>(node: QuerySignalNode<V>, firstOnly: boolean): V | ReadonlyArray<V> {
  const lView = node._lView;
  const queryIndex = node._queryIndex;

  // There are 2 conditions under which we want to return "empty" results instead of the ones
  // collected by a query:
  //
  // 1) a given query wasn't created yet (this is a period of time between the directive creation
  // and execution of the query creation function) - in this case a query doesn't exist yet and we
  // don't have any results to return.
  //
  // 2) we are in the process of constructing a view (the first
  // creation pass didn't finish) and a query might have partial results, but we don't want to
  // return those - instead we do delay results collection until all nodes had a chance of matching
  // and we can present consistent, "atomic" (on a view level) results.
  if (lView === undefined || queryIndex === undefined || lView[FLAGS] & LViewFlags.CreationMode) {
    return (firstOnly ? undefined : EMPTY_ARRAY) as V;
  }

  const queryList = loadQueryInternal<V>(lView, queryIndex);
  const results = getQueryResults<V>(lView, queryIndex);

  queryList.reset(results, unwrapElementRef);

  if (firstOnly) {
    return queryList.first;
  } else {
    // TODO: remove access to the private _changesDetected field by abstracting / removing usage of
    // QueryList in the signal-based queries (perf follow-up)
    const resultChanged = (queryList as any as {_changesDetected: boolean})._changesDetected;
    if (resultChanged || node._flatValue === undefined) {
      return (node._flatValue = queryList.toArray());
    }
    return node._flatValue;
  }
}