handleResponse static method

Implementation

static dynamic handleResponse(http.Response response) {
  String body = response.body;
  final status = response.statusCode;

  // The whole 2xx range, not only 200: a 201 Created or 204 No Content is an
  // ordinary answer, and treating either as a failure would break the SDK
  // against any endpoint that starts using them.
  if (status >= 200 && status < 300) {
    if (body == '') return {};

    try {
      return json.decode(body);
    } on FormatException catch (err) {
      // A success status carrying something that is not JSON: a captive
      // portal, or a proxy answering 200 with an HTML error page. Raw, this
      // surfaced as `FormatException: Unexpected character (at character 1)`
      // from inside the SDK, naming neither the status nor what arrived.
      throw FetchDataException(
        'The response was not JSON ($err): ${_truncate(body)}',
        body: body,
        status: status,
      );
    }
  }

  switch (status) {
    case 400:
      throw BadRequestException(body, status: status);
    case 401:
      throw UnauthorizedException(body, status: status);
    // Split from 401 rather than sharing its type. A 403 is the database
    // saying a collection's policy denies this, which the caller cannot fix by
    // signing in again - and treating it as an expired session sent users to a
    // login screen for an operation they were never permitted to perform.
    case 403:
      throw ForbiddenException(body, status: status);
    case 404:
      throw NotFoundException(body, status: status);
    // The row changed between the policy check and the conditional write. The
    // request was fine and can be retried once the caller has re-read it, so
    // this must not fall through to FetchDataException and be announced as an
    // internal server error.
    case 409:
      throw ConflictException(body, status: status);
    case 429:
      throw RateLimitedException(body, status: status);
    default:
      // `body` stays the response exactly as it arrived. The status is a field
      // now rather than something appended to the message text.
      if (body != '') {
        throw FetchDataException(body, body: body, status: status);
      } else {
        throw FetchDataException(
          'An unexpected error occurred',
          status: status,
        );
      }
  }
}