Response

Response converters help users to automatically convert returned type into response.

Response Example

auto resp() -> awaitable<response>
{
  co_return response::ok()
      .set_header(http::field::content_type, mime::text_plain())
      .set_body("Hello World!");
}

auto text() -> awaitable<std::string>
{
  co_return "Hello World!";
}

auto binary() -> awaitable<std::vector<std::uint8_t>>
{
  co_return std::vector<std::uint8_t> { 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20,
                                        0x57, 0x6f, 0x72, 0x6c, 0x64, 0x21 };
}

auto variant(path_of<std::tuple<bool>> path)
    -> awaitable<std::variant<std::string, std::vector<std::uint8_t>>>
{
  auto [text] = path;
  if (text) {
    co_return "Hello World!";
  } else {
    co_return std::vector<std::uint8_t> { 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20,
                                          0x57, 0x6f, 0x72, 0x6c, 0x64, 0x21 };
  }
}

Note

To enable response converter for custom type, implement customization point to_response_t.

class my_error {
  std::string msg_;

public:
  my_error(std::string msg)
      : msg_(std::move(msg))
  {
  }

  auto message() const noexcept -> const std::string&
  {
    return msg_;
  }

  template <decay_to<my_error> Self>
  friend auto tag_invoke(fitoria::web::to_response_t, Self&& self) -> response
  {
    return response::not_found()
        .set_header(http::field::content_type, mime::text_plain())
        .set_body(self.message());
  }
};

auto err() -> awaitable<my_error>
{
  co_return my_error("You will never get anything!");
}

Built-in Response Converters

Response Converter	Description
std::string	Put string into response body.	Content-Type: text/plain will be inserted.
std::vector<T>	Put std::vector<T> into response body.	Content-Type: application/octet-stream will be inserted.
std::variant<Ts...>	Convert any of Ts... into response body.	Note that Ts... must be convertible to response.
expected<T, E>	Convert T or E into response body.	Note that T and E must be convertible to response.
stream_file	Put stream_file into response body.	Content-Type: application/octet-stream will be inserted and Transfer-Encoding: Chunked will be used.