change method Null safety

Request change({dynamic uri, dynamic headers, dynamic patchHeaders, dynamic body, Map<String, dynamic>? form, Map<String, dynamic>? json, Map<String, String>? cookies, Encoding? encoding})

Creates a Request object by changing or augmenting the properties.

When uri, headers or body is specified, they will override the original corresponding values.

Use patchHeaders to keep the current headers and also add override its values (if they already exist) or add values (if they did not exist).

Implementation

Request change({
  dynamic uri,
  dynamic headers,
  dynamic patchHeaders,
  dynamic body,
  Map<String, dynamic>? form,
  Map<String, dynamic>? json,
  Map<String, String>? cookies,
  c.Encoding? encoding,
}) {
  encoding ??= c.utf8;
  Uri? parsedUri;
  if (uri != null) {
    assert(uri is String || uri is Uri);
    parsedUri = uri is Uri ? uri : Uri.parse(uri.toString());
  }

  final newHeaders = headers == null
      ? this.headers.clone()
      : wrapHeaders(headers, clone: true)!;
  if (patchHeaders != null) {
    final patching = wrapHeaders(patchHeaders)!;
    patching.keys.forEach((key) {
      newHeaders.remove(key);
      newHeaders.add(key, patching[key]);
    });
  }

  final newBody = _buildBody(
      body ?? this.body, encoding, newHeaders, form, json, cookies);

  return Request._(
    method,
    parsedUri ?? this.uri,
    newHeaders,
    newBody,
    persistentConnection,
    followRedirects,
    maxRedirects,
    timeout,
  );
}