void DocumentSourceLookUp::serializeToArray(std::vector<Value>& array, bool explain) const {
MutableDocument output(DOC(
getSourceName() << DOC("from" << _fromNs.coll() << "as" << _as.fullPath() << "localField"
<< _localField.fullPath()
<< "foreignField"
<< _foreignField.fullPath())));
if (explain) {
if (_handlingUnwind) {
const boost::optional<FieldPath> indexPath = _unwindSrc->indexPath();
output[getSourceName()]["unwinding"] =
Value(DOC("preserveNullAndEmptyArrays"
<< _unwindSrc->preserveNullAndEmptyArrays()
<< "includeArrayIndex"
<< (indexPath ? Value(indexPath->fullPath()) : Value())));
}
if (_matchSrc) {
// Our output does not have to be parseable, so include a "matching" field with the
// descended match expression.
output[getSourceName()]["matching"] =
Value(DocumentSourceMatch::descendMatchOnPath(
_matchSrc->getMatchExpression(), _as.fullPath(), pExpCtx)
->getQuery());
}
array.push_back(Value(output.freeze()));
} else {
array.push_back(Value(output.freeze()));
if (_handlingUnwind) {
_unwindSrc->serializeToArray(array);
}
if (_matchSrc) {
// '_matchSrc' tracks the originally specified $match. We descend upon the $match in the
// first call to getNext(), at which point we are confident that we no longer need to
// serialize the $lookup again.
_matchSrc->serializeToArray(array);
}
}
}
