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response.ts
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response.ts
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// Copyright 2018-2020 the oak authors. All rights reserved. MIT license.
import { contentType, Status } from "./deps.ts";
import type { Request } from "./request.ts";
import type { ServerResponse } from "./types.d.ts";
import { encodeUrl, isHtml, isRedirectStatus } from "./util.ts";
type Body =
| string
| number
| bigint
| boolean
| symbol
// deno-lint-ignore ban-types
| object
| undefined
| null;
type BodyFunction = () => Body | Promise<Body>;
/** A symbol that indicates to `response.redirect()` to attempt to redirect
* back to the request referrer. For example:
*
* ```ts
* import { Application, REDIRECT_BACK } from "https://deno.land/x/oak/mod.ts";
*
* const app = new Application();
*
* app.use((ctx) => {
* if (ctx.request.url.pathName === "/back") {
* ctx.response.redirect(REDIRECT_BACK, "/");
* }
* });
*
* await app.listen({ port: 80 });
* ```
*/
export const REDIRECT_BACK = Symbol("redirect backwards");
const BODY_TYPES = ["string", "number", "bigint", "boolean", "symbol"];
const encoder = new TextEncoder();
/** Guard for `Deno.Reader`. */
// deno-lint-ignore no-explicit-any
function isReader(value: any): value is Deno.Reader {
return value && typeof value === "object" && "read" in value &&
typeof value.read === "function";
}
async function convertBody(
body: Body | BodyFunction,
type?: string,
): Promise<[Uint8Array | Deno.Reader | undefined, string | undefined]> {
let result: Uint8Array | Deno.Reader | undefined;
if (BODY_TYPES.includes(typeof body)) {
const bodyText = String(body);
result = encoder.encode(bodyText);
type = type ?? (isHtml(bodyText) ? "html" : "text/plain");
} else if (body instanceof Uint8Array || isReader(body)) {
result = body;
} else if (body && typeof body === "object") {
result = encoder.encode(JSON.stringify(body));
type = type ?? "json";
} else if (typeof body === "function") {
const result = body.call(null);
return convertBody(await result, type);
} else if (body) {
throw new TypeError("Response body was set but could not convert.");
}
return [result, type];
}
/** An interface to control what response will be sent when the middleware
* finishes processing the request. */
export class Response {
#body?: Body | BodyFunction;
#headers = new Headers();
#request: Request;
#resources: number[] = [];
#serverResponse?: ServerResponse;
#status?: Status;
#type?: string;
#writable = true;
#getBody = async (): Promise<Uint8Array | Deno.Reader | undefined> => {
const [body, type] = await convertBody(this.body, this.type);
this.type = type;
return body;
};
#setContentType = (): void => {
if (this.type) {
const contentTypeString = contentType(this.type);
if (contentTypeString && !this.headers.has("Content-Type")) {
this.headers.append("Content-Type", contentTypeString);
}
}
};
/** The body of the response. The body will be automatically processed when
* the response is being sent and converted to a `Uint8Array` or a
* `Deno.Reader`. */
get body(): Body | BodyFunction {
return this.#body;
}
/** The body of the response. The body will be automatically processed when
* the response is being sent and converted to a `Uint8Array` or a
* `Deno.Reader`. */
set body(value: Body | BodyFunction) {
if (!this.#writable) {
throw new Error("The response is not writable.");
}
this.#body = value;
}
/** Headers that will be returned in the response. */
get headers(): Headers {
return this.#headers;
}
/** Headers that will be returned in the response. */
set headers(value: Headers) {
if (!this.#writable) {
throw new Error("The response is not writable.");
}
this.#headers = value;
}
/** The HTTP status of the response. If this has not been explicitly set,
* reading the value will return what would be the value of status if the
* response were sent at this point in processing the middleware. If the body
* has been set, the status will be `200 OK`. If a value for the body has
* not been set yet, the status will be `404 Not Found`. */
get status(): Status {
if (this.#status) {
return this.#status;
}
const typeofbody = typeof this.body;
return this.body &&
(BODY_TYPES.includes(typeofbody) || typeofbody === "object")
? Status.OK
: Status.NotFound;
}
/** The HTTP status of the response. If this has not been explicitly set,
* reading the value will return what would be the value of status if the
* response were sent at this point in processing the middleware. If the body
* has been set, the status will be `200 OK`. If a value for the body has
* not been set yet, the status will be `404 Not Found`. */
set status(value: Status) {
if (!this.#writable) {
throw new Error("The response is not writable.");
}
this.#status = value;
}
/** The media type, or extension of the response. Setting this value will
* ensure an appropriate `Content-Type` header is added to the response. */
get type(): string | undefined {
return this.#type;
}
/** The media type, or extension of the response. Setting this value will
* ensure an appropriate `Content-Type` header is added to the response. */
set type(value: string | undefined) {
if (!this.#writable) {
throw new Error("The response is not writable.");
}
this.#type = value;
}
/** A read-only property which determines if the response is writable or not.
* Once the response has been processed, this value is set to `false`. */
get writable(): boolean {
return this.#writable;
}
constructor(request: Request) {
this.#request = request;
}
/** Add a resource to the list of resources that will be closed when the
* request is destroyed. */
addResource(rid: number): void {
this.#resources.push(rid);
}
/** Release any resources that are being tracked by the response. */
destroy(): void {
this.#writable = false;
this.#body = undefined;
this.#serverResponse = undefined;
for (const rid of this.#resources) {
Deno.close(rid);
}
}
/** Sets the response to redirect to the supplied `url`.
*
* If the `.status` is not currently a redirect status, the status will be set
* to `302 Found`.
*
* The body will be set to a message indicating the redirection is occurring.
*/
redirect(url: string | URL): void;
/** Sets the response to redirect back to the referrer if available, with an
* optional `alt` URL if there is no referrer header on the request. If there
* is no referrer header, nor an `alt` parameter, the redirect is set to `/`.
*
* If the `.status` is not currently a redirect status, the status will be set
* to `302 Found`.
*
* The body will be set to a message indicating the redirection is occurring.
*/
redirect(url: typeof REDIRECT_BACK, alt?: string | URL): void;
redirect(
url: string | URL | typeof REDIRECT_BACK,
alt: string | URL = "/",
): void {
if (url === REDIRECT_BACK) {
url = this.#request.headers.get("Referrer") ?? String(alt);
} else if (typeof url === "object") {
url = String(url);
}
this.headers.set("Location", encodeUrl(url));
if (!this.status || !isRedirectStatus(this.status)) {
this.status = Status.Found;
}
if (this.#request.accepts("html")) {
url = encodeURI(url);
this.type = "text/html; charset=utf-8";
this.body = `Redirecting to <a href="${url}">${url}</a>.`;
return;
}
this.type = "text/plain; charset=utf-8";
this.body = `Redirecting to ${url}.`;
}
/** Take this response and convert it to the response used by the Deno net
* server. Calling this will set the response to not be writable.
*
* Most users will have no need to call this method. */
async toServerResponse(): Promise<ServerResponse> {
if (this.#serverResponse) {
return this.#serverResponse;
}
// Process the body
const body = await this.#getBody();
// If there is a response type, set the content type header
this.#setContentType();
const { headers } = this;
// If there is no body and no content type and no set length, then set the
// content length to 0
if (
!(
body ||
headers.has("Content-Type") ||
headers.has("Content-Length")
)
) {
headers.append("Content-Length", "0");
}
this.#writable = false;
return this.#serverResponse = {
status: this.#status ?? (body ? Status.OK : Status.NotFound),
body,
headers,
};
}
}