2.x API

Request

The req object represents the HTTP request and has properties for the request query string, parameters, body, HTTP headers, and so on. In this documentation and by convention, the object is always referred to as req (and the HTTP response is res) but its actual name is determined by the parameters to the callback function in which you’re working.

For example:

app.get("/user/:id", function (req, res) {
  res.send("user " + req.params.id);
});

But you could just as well have:

app.get("/user/:id", function (request, response) {
  response.send("user " + request.params.id);
});

The req object is an enhanced version of Deno’s own request object and supports all built-in fields and methods.

Properties

req.app

This property holds a reference to the instance of the Opine application that is using the middleware.

If you follow the pattern in which you create a module that just exports a middleware function and dynamic import() it in your main file, then the middleware can access the Opine instance via req.app

For example:

// index.ts
app.get("/xpoweredbyenabled", (await import("./myMiddleware.ts")).myMiddleware);

// myMiddleware.ts
export const myMiddleware = function (req: any, res: any) {
  res.send("'X-Powered-By' header enabled: " + req.app.get("x-powered-by"));
};

req.baseUrl

The URL path on which a router instance was mounted.

The req.baseUrl property is similar to the mountpath property of the app object, except app.mountpath returns the matched path pattern(s).

For example:

const greet = Router();

greet.get("/jp", function (req, res) {
  console.log(req.baseUrl); // /greet
  res.send("Konichiwa!");
});

app.use("/greet", greet); // load the router on '/greet'

Even if you use a path pattern or a set of path patterns to load the router, the baseUrl property returns the matched string, not the pattern(s). In the following example, the greet router is loaded on two path patterns.

app.use(["/gre+t", "/hel{2}o"], greet); // load the router on '/gre+t' and '/hel{2}o'

When a request is made to /greet/jp, req.baseUrl is “/greet”. When a request is made to /hello/jp, req.baseUrl is “/hello”.

req.body

Contains the data submitted in the request body. By default the req.body is a Deno.Reader, and needs to be read using a body-parsing middleware such as json() or urlencoded().

The following example shows how to use body-parsing middleware to populate req.body.

import {
  json,
  opine,
  urlencoded,
} from "https://deno.land/x/opine@2.3.4/mod.ts";

const app = opine();

app.use(json()); // for parsing application/json
app.use(urlencoded()); // for parsing application/x-www-form-urlencoded

app.post("/profile", function (req, res, next) {
  console.log(req.body);
  res.json(req.body);
});

The following example shows how to implement your own simple body-parsing middleware to transform req.body into a raw string:

import opine from "https://deno.land/x/opine@2.3.4/mod.ts";

import { readAll } from "https://deno.land/std@0.120.0/streams/conversion.ts";

const app = opine();

const bodyParser = async function (req, res, next) {
  const rawBody = await readAll(req.raw);
  const decodedBody = decoder.decode(rawBody);

  req.body = decodedBody;
};

app.use(bodyParser);

app.post("/profile", function (req, res, next) {
  console.log(req.body);
  res.send(req.body);
});

req.fresh

When the response is still “fresh” in the client’s cache true is returned, otherwise false is returned to indicate that the client cache is now stale and the full response should be sent.

When a client sends the Cache-Control: no-cache request header to indicate an end-to-end reload request, this module will return false to make handling these requests transparent.

Further details for how cache validation works can be found in the HTTP/1.1 Caching Specification.

console.dir(req.fresh);
// => true

req.hostname

Contains the hostname derived from the Host HTTP header.

When the trust proxy setting does not evaluate to false, this property will instead get the value from the X-Forwarded-Host header field. This header can be set by the client or by the proxy.

If there is more than one X-Forwarded-Host header in the request, the value of the first header is used. This includes a single header with comma-separated values, in which the first value is used.

// Host: "example.com:3000"
console.dir(req.hostname);
// => 'example.com'

req.ip

Contains the remote IP address of the request.

When the trust proxy setting does not evaluate to false, the value of this property is derived from the left-most entry in the X-Forwarded-For header. This header can be set by the client or by the proxy.

console.dir(req.ip);
// => '127.0.0.1'

req.ips

When the trust proxy setting does not evaluate to false, this property contains an array of IP addresses specified in the X-Forwarded-For request header. Otherwise, it contains an empty array. This header can be set by the client or by the proxy.

For example, if X-Forwarded-For is client, proxy1, proxy2, req.ips would be ["client", "proxy1", "proxy2"], where proxy2 is the furthest downstream.

req.method

Contains a string corresponding to the HTTP method of the request: GET, POST, PUT, and so on.

req.originalUrl

This property is much like req.url; however, it retains the original request URL, allowing you to rewrite req.url freely for internal routing purposes. For example, the “mounting” feature of app.use() will rewrite req.url to strip the mount point.

// GET /search?q=something
console.dir(req.originalUrl);
// => '/search?q=something'

In a middleware function, req.originalUrl is a combination of req.baseUrl and req.path, as shown in the following example.

app.use("/admin", function (req, res, next) {
  // GET 'http://www.example.com/admin/new'
  console.dir(req.originalUrl); // '/admin/new'
  console.dir(req.baseUrl); // '/admin'
  console.dir(req.path); // '/new'
  next();
});

req.params

This property is an object containing properties mapped to the named route “parameters”. For example, if you have the route /user/:name, then the “name” property is available as req.params.name. This object defaults to {}.

// GET /user/tj
console.dir(req.params.name);
// => 'tj'

When you use a regular expression for the route definition, capture groups are provided in the array using req.params[n], where n is the n^th capture group. This rule is applied to unnamed wild card matches with string routes such as /file/*:

// GET /file/javascripts/jquery.js
console.dir(req.params[0]);
// => 'javascripts/jquery.js'

Any changes made to the req.params object in a middleware or route handler will be reset.

NOTE: Opine automatically decodes the values in req.params (using decodeURIComponent).

req.path

Contains the path part of the request URL.

// example.com/users?sort=desc
console.dir(req.path);
// => '/users'

When called from a middleware, the mount point is not included in req.path. See app.use() for more details.

req.protocol

Contains the request protocol string: either http or (for TLS requests) https.

When the trust proxy setting does not evaluate to false, this property will use the value of the X-Forwarded-Proto header field if present. This header can be set by the client or by the proxy.

console.dir(req.protocol);
// => 'http'

req.query

This property is an object containing a property for each query string parameter in the route.

As req.query’s shape is based on user-controlled input, all properties and values in this object are untrusted and should be validated before trusting. For example, req.query.foo.toString() may fail in multiple ways, for example foo may not be there or may not be a string, and toString may not be a function and instead a string or other user-input.

// GET /search?q=deno+land
console.dir(req.query.q);
// => 'deno land'

// GET /shoes?order=desc&shoe[color]=blue&shoe[type]=converse
console.dir(req.query.order);
// => 'desc'

console.dir(req.query.shoe.color);
// => 'blue'

console.dir(req.query.shoe.type);
// => 'converse'

// GET /shoes?color[]=blue&color[]=black&color[]=red
console.dir(req.query.color);
// => ['blue', 'black', 'red']

req.raw

Contains the data submitted in the request body. The req.raw is a Deno.Reader, and needs to be read using a body-parsing middleware such as json() or urlencoded(). Unlike the req.body property, req.raw cannot be overwritten and will always return the original request body.

req.route

Contains the currently-matched route, a string. For example:

app.get("/user/:id?", function userIdHandler(req, res) {
  console.log(req.route);
  res.send("GET");
});

Example output from the previous snippet:

{ path: '/user/:id?',
  stack:
   [ { handle: [Function: userIdHandler],
       name: 'userIdHandler',
       params: undefined,
       path: undefined,
       keys: [],
       regexp: /^\/?$/i,
       method: 'get' } ],
  methods: { get: true } }

req.secure

A Boolean property that is true if a TLS connection is established. Equivalent to:

console.dir(req.protocol === "https");
// => true

req.stale

Indicates whether the request is “stale,” and is the opposite of req.fresh. For more information, see req.fresh.

console.dir(req.stale);
// => true

req.subdomains

An array of subdomains in the domain name of the request.

// Host: "deno.dinosaurs.example.com"
console.dir(req.subdomains);
// => ['dinosaurs', 'deno']

The application property subdomain offset, which defaults to 2, is used for determining the beginning of the subdomain segments. To change this behavior, change its value using app.set.

req.url

Request URL string. This contains only the URL that is present in the actual HTTP request. Unlike req.originalUrl, req.url can be rewritten freely for internal routing purposes. For example, the “mounting” feature of app.use() will rewrite req.url to strip the mount point.

req.xhr

A Boolean property that is true if the request’s X-Requested-With header field is “XMLHttpRequest”, indicating that the request was issued by a client library such as jQuery.

console.dir(req.xhr);
// => true

Methods

req.accepts(types)

Checks if the specified content types are acceptable, based on the request’s Accept HTTP header field. The method returns the best match, or if none of the specified content types is acceptable, returns empty (in which case, the application should respond with 406 "Not Acceptable").

The type value may be a single MIME type string (such as “application/json”), an extension name such as “json”, a comma-delimited list, or an array. For a list or array, the method returns the best match (if any).

// Accept: text/html
req.accepts("html");
// => "html"

// Accept: text/*, application/json
req.accepts("html");
// => "html"
req.accepts("text/html");
// => "text/html"
req.accepts(["json", "text"]);
// => "json"
req.accepts("application/json");
// => "application/json"

// Accept: text/*, application/json
req.accepts("image/png");
req.accepts("png");
// => false

// Accept: text/*;q=.5, application/json
req.accepts(["html", "json"]);
// => "json"

req.acceptsCharsets(charset [, …])

Returns the first accepted charset of the specified character sets, based on the request’s Accept-Charset HTTP header field. If none of the specified charsets is accepted, returns empty.

req.acceptsEncodings(encoding [, …])

Returns the first accepted encoding of the specified encodings, based on the request’s Accept-Encoding HTTP header field. If none of the specified encodings is accepted, returns empty.

req.acceptsLanguages(lang [, …])

Returns the first accepted language of the specified languages, based on the request’s Accept-Language HTTP header field. If none of the specified languages is accepted, returns empty.

req.get(field)

Returns the specified HTTP request header field (case-insensitive match). The Referrer and Referer fields are interchangeable.

req.get("Content-Type");
// => "text/plain"

req.get("content-type");
// => "text/plain"

req.get("Something");
// => undefined

req.is(type)

Returns the matching content type if the incoming request’s “Content-Type” HTTP header field matches the MIME type specified by the type parameter. If the request has no body, returns null. Returns false otherwise.

// With Content-Type: text/html; charset=utf-8
req.is("html");
// => 'html'
req.is("text/html");
// => 'text/html'
req.is("text/*");
// => 'text/*'

// When Content-Type is application/json
req.is("json");
// => 'json'
req.is("application/json");
// => 'application/json'
req.is("application/*");
// => 'application/*'

req.is("html");
// => false

For more information, or if you have issues or concerns, see Node’s type-is and/or Deno’s type_is.

req.range(size[, options])

Range header parser.

The size parameter is the maximum size of the resource.

The options parameter is an object that can have the following properties.

Property	Type	Description
`combine`	Boolean	Specify if overlapping & adjacent ranges should be combined, defaults to `false`. When `true`, ranges will be combined and returned as if they were specified that way in the header.

An array of ranges will be returned or negative numbers indicating an error parsing.

-2 signals a malformed header string
-1 signals an unsatisfiable range

// parse header from request
const range = req.range(1000);

// the type of the range
if (range.type === "bytes") {
  // the ranges
  range.forEach(function (r) {
    // do something with r.start and r.end
  });
}

req.upgrade()

Upgrades the HTTP connection to a WebSocket connection by internally calling Deno.upgradeWebSocket(req). Returns the created WebSocket.

app.get("/ws", async (req, _res, next) => {
  if (req.headers.get("upgrade") === "websocket") {
    const socket = req.upgrade();
    handleSocket(socket);
  } else {
    next();
  }
});