Class Response

starlette/responses.py:29–170

class Response:
    media_type = None
    charset = "utf-8"

    def __init__(
        self,
        content: Any = None,
        status_code: int = 200,
        headers: Mapping[str, str] | None = None,
        media_type: str | None = None,
        background: BackgroundTask | None = None,
    ) -> None:
        self.status_code = status_code
        if media_type is not None:
            self.media_type = media_type
        self.background = background
        self.body = self.render(content)
        self.init_headers(headers)

    def render(self, content: Any) -> bytes | memoryview:
        if content is None:
            return b""
        if isinstance(content, bytes | memoryview):
            return content
        return content.encode(self.charset)  # type: ignore

    def init_headers(self, headers: Mapping[str, str] | None = None) -> None:
        if headers is None:
            raw_headers: list[tuple[bytes, bytes]] = []
            populate_content_length = True
            populate_content_type = True
        else:
            raw_headers = [(k.lower().encode("latin-1"), v.encode("latin-1")) for k, v in headers.items()]
            keys = [h[0] for h in raw_headers]
            populate_content_length = b"content-length" not in keys
            populate_content_type = b"content-type" not in keys

        body = getattr(self, "body", None)
        if (
            body is not None
            and populate_content_length
            and not (self.status_code < 200 or self.status_code in (204, 304))
        ):
            content_length = str(len(body))
            raw_headers.append((b"content-length", content_length.encode("latin-1")))

        content_type = self.media_type
        if content_type is not None and populate_content_type:
            if content_type.startswith("text/") and "charset=" not in content_type.lower():
                content_type += "; charset=" + self.charset
            raw_headers.append((b"content-type", content_type.encode("latin-1")))

        self.raw_headers = raw_headers

    @property
    def headers(self) -> MutableHeaders:
        if not hasattr(self, "_headers"):
            self._headers = MutableHeaders(raw=self.raw_headers)