jsonArrayBytes function

Stream<List<int>> jsonArrayBytes(Stream<Object?> items, { bool phpCompatible = false, String? wrap, int flushBytes = 64 * 1024, })

The bytes of a JSON array of items, written as the items arrive: [ and ] around them, a comma between, each item encoded with Response.encodeJson (or Response.encodePhpJson with phpCompatible) as soon as it is produced, so a response never holds every row at once. With wrap, the array is the value of that key in an object: {"data":[...]}, as Laravel's response()->streamJson() writes.

Bytes go out in chunks of about flushBytes (64 KiB), a balance between socket writes and memory; the last chunk may be smaller. The result is byte for byte what Response.json writes for the collected list.

Implementation

Stream<List<int>> jsonArrayBytes(
  Stream<Object?> items, {
  bool phpCompatible = false,
  String? wrap,
  int flushBytes = 64 * 1024,
}) async* {
  final encode = phpCompatible ? Response.encodePhpJson : Response.encodeJson;
  final buffer = StringBuffer();
  if (wrap != null) {
    buffer
      ..write('{')
      ..write(encode(wrap))
      ..write(':');
  }
  buffer.write('[');
  var first = true;
  await for (final item in items) {
    if (!first) {
      buffer.write(',');
    }
    first = false;
    buffer.write(encode(item));
    if (buffer.length >= flushBytes) {
      yield utf8.encode(buffer.toString());
      buffer.clear();
    }
  }
  buffer.write(']');
  if (wrap != null) {
    buffer.write('}');
  }
  yield utf8.encode(buffer.toString());
}