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Server framework for Deno

Pogo is an easy-to-use, safe, and expressive framework for writing web servers and applications. It is inspired by hapi.

Documentation

Supports Deno v1.0.0 and higher.

Contents

Why?

  • Designed to encourage reliable and testable applications.
  • Routes are simple, pure functions that return values directly.
  • Automatic JSON responses from objects.
  • Built-in support for React and JSX.

Usage

Save the code below to a file named server.js and run it with a command like deno --allow-net server.js. Then visit http://localhost:3000 in your browser and you should see “Hello, world!” on the page.

import pogo from 'https://deno.land/x/pogo/main.ts';

const server = pogo.server({ port : 3000 });

server.router.get('/', () => {
    return 'Hello, world!';
});

server.start();

The examples that follow will build on this to add more capabilities to the server. Some advanced features may require additional permission flags or different file extensions. If you get stuck or need more concrete examples, be sure to check out the example projects.

Adding routes

A route matches an incoming request to a handler function that creates a response

Adding routes is easy, just call server.route() and pass it a single route or an array of routes. You can call server.route() multiple times. You can even chain calls to server.route(), because it returns the server instance.

Add routes in any order you want to, it’s safe! Pogo orders them internally by specificity, such that their order of precedence is stable and predictable and avoids ambiguity or conflicts.

server.route({ method : 'GET', path : '/hi', handler : () => 'Hello!' });
server.route({ method : 'GET', path : '/bye', handler : () => 'Goodbye!' });
server
    .route({ method : 'GET', path : '/hi', handler : () => 'Hello!' });
    .route({ method : 'GET', path : '/bye', handler : () => 'Goodbye!' });
server.route([
    { method : 'GET', path : '/hi', handler : () => 'Hello!' },
    { method : 'GET', path : '/bye', handler : () => 'Goodbye!' }
]);

You can also configure the route to handle multiple methods by using an array, or '*' to handle all possible methods.

server.route({ method : ['GET', 'POST'], path : '/hi', handler : () => 'Hello!' });
server.route({ method : '*', path : '/hi', handler : () => 'Hello!' });

Serve static files

You can use Deno.readFile() to serve the contents of a file from the filesystem.

Note that currently you should specify the content type of the file using response.type(). Future versions of Pogo will provide more egornomic APIs for static files that handle this automatically.

server.router.get('/', async (request, h) => {
    const buffer = await Deno.readFile('./hello.jpg');
    return h.response(buffer).type('image/jpeg');
});

React and JSX support

JSX is a shorthand syntax for JavaScript that looks like HTML and is useful for constructing web pages

You can do webpage templating with React inside of route handlers, using either JSX or React.createElement().

Pogo automatically renders React elements using ReactDOMServer.renderToStaticMarkup() and sends the response as HTML.

Save the code below to a file named server.jsx and run it with a command like deno --allow-net server.jsx. The .jsx extension is important, as it tells Deno to compile the JSX syntax. You can also use TypeScript by using .tsx instead of .jsx. The type definitions should load automatically from the Pika CDN, but if you run into problems when using .tsx, try loading them manually (see deno_types).

import React from 'https://cdn.pika.dev/react';
import pogo from 'https://deno.land/x/pogo/main.ts';

const server = pogo.server({ port : 3000 });

server.router.get('/', () => {
    return <h1>Hello, world!</h1>;
});

server.start();

Writing tests

When it comes time to write tests for your app, Pogo has you covered with server.inject().

By injecting a request into the server directly, we can completely avoid the need to listen on an available port, make HTTP connections, and all of the problems and complexity that come along with that. You should focus on writing your application logic and server.inject() makes that easier.

The server still processes the request using the same code paths that a normal HTTP request goes through, so you can rest assured that your tests are meaningful and realistic.

const response = await server.inject({
    method : 'GET',
    url    : '/users'
});

API

pogo.server(options)

Returns a Server instance, which can then be used to add routes and start listening for requests.

const server = pogo.server();

options

Type: object

catchAll

Type: function

Optional route handler to be used as a fallback for requests that do not match any other route. This overrides the default 404 Not Found behavior built into the framework. Shortcut for server.router.all('/{catchAll*}', catchAll).

pogo.server({
    catchAll(request, h) {
        return h.response('the void').code(404);
    }
});
certFile

Type: string
Example: '/path/to/file.cert'

Optional filepath to an X.509 public key certificate for the server to read when server.start() is called, in order to set up HTTPS. Requires the use of the keyFile option.

hostname

Type: string
Default: 'localhost'

Optional domain or IP address for the server to listen on when server.start() is called. Use '0.0.0.0' to listen on all available addresses, as mentioned in the security documentation.

keyFile

Type: string
Example: '/path/to/file.key'

Optional filepath to a private key for the server to read when server.start() is called, in order to set up HTTPS. Requires the use of the certFile option.

port

Type: number
Example: 3000

Any valid port number (0 to 65535) for the server to listen on when server.start() is called. Use 0 to listen on an available port assigned by the operating system.

pogo.router(options?)

Returns a Router instance, which can then be used to add routes.

const router = pogo.router();

Server

The server object returned by pogo.server() represents your web server. When you start the server, it begins listening for HTTP requests, processes those requests when they are received, and makes the content within each request available to the route handlers that you specify.

server.inject(request)

Performs a request directly to the server without using the network. Useful when writing tests, to avoid conflicts from multiple servers trying to listen on the same port number.

Returns a Promise for a Response instance.

const response = await server.inject({
    method : 'GET',
    url    : '/'
});
request

Type: object

method

Type: string
Example: 'GET'

Any valid HTTP method, such as GET or POST. Used to lookup the route handler.

url

Type: string
Example: '/'

Any valid URL path. Used to lookup the route handler.

server.route(route, options?, handler?)

Adds a route to the server so that the server knows how to respond to requests that match the given HTTP method and URL path. Shortcut for server.router.add().

Returns the server so other methods can be chained.

server.route({ method : 'GET', path : '/', handler : () => 'Hello, World!' });
server.route({ method : 'GET', path : '/' }, () => 'Hello, World!');
server.route('/', { method : 'GET' }, () => 'Hello, World!');
route

Type: object | string | Router | Array<object | string | Router>

method

Type: string | Array<string>
Example: 'GET'

Any valid HTTP method, array of methods, or '*' to match all methods. Used to limit which requests will trigger the route handler.

path

Type: string
Example: '/users/{userId}'

Any valid URL path. Used to limit which requests will trigger the route handler.

Supports path parameters with dynamic values, which can be accessed in the handler as request.params.

handler(request, h)

Type: function

  • request is a Request instance with properties for headers, method, url, and more.
  • h is a Response Toolkit instance, which has utility methods for modifying the response.

The implementation for the route that handles requests. Called when a request is received that matches the method and path specified in the route options.

The handler must return one of:

  • A string, which will be sent as HTML.
  • An object, which will be stringified and sent as JSON.
  • A Uint8Array, which will be sent as-is (raw bytes).
  • A Response, which will send the response.body, if any.
  • Any object that implements the Reader interface, such as a File or Buffer.
  • An Error, which will send an appropriate HTTP error code - returning an error is the same as throwing it.
  • A Promise for any of the above types.

An appropriate Content-Type header will be set automatically based on the response body before the response is sent. You can use response.type() to override the default behavior.

server.router

Type: Router

The route manager for the server, which contains the routing table for all known routes, as well as various methods for adding routes to the routing table.

server.start()

Begins listening for requests on the hostname and port specified in the server options.

Returns a Promise that resolves when the server is listening.

await server.start();
console.log('Listening for requests');

server.stop()

Stops accepting new requests. Any existing requests that are being processed will not be interrupted.

Returns a Promise that resolves when the server has stopped listening.

await server.stop();
console.log('Stopped listening for requests');

Request

The request object passed to route handlers represents an HTTP request that was sent to the server. It is similar to an instance of Deno’s ServerRequest class, with some additions.

It provides properties and methods for inspecting the content of the request.

request.body

Type: Reader

The HTTP body value.

You can read raw bytes from the body in chunks with request.body.read(), which takes a Uint8Array as an argument to copy the bytes into and returns a Promise for either the number of bytes read or null when the body is finished being read.

const decoder = new TextDecoder();
const buffer = new Uint8Array(20);
const numBytesRead = await request.body.read(buffer);
const bodyText = decoder.decode(buffer.subarray(0, numBytesRead));

To get the body as a string, pass it to Deno.readAll() and decode the result, as shown below. Note that doing so will cause the entire body to be read into memory all at once, which is convenient, but may be inappropriate for requests with a very large body.

const decoder = new TextDecoder();
const bodyText = decoder.decode(await Deno.readAll(request.body));

request.headers

Type: Headers

Contains the HTTP headers that were sent in the request, such as Accept, User-Agent, and others.

request.host

Type: string
Example: 'localhost:3000'

The value of the HTTP Host header, which is a combination of the hostname and port at which the server received the request, separated by a : colon. Useful for returning different content depending on which URL your visitors use to access the server. Shortcut for request.url.host.

To get the hostname, which does not include the port number, see request.hostname.

request.hostname

Type: string
Example: 'localhost'

The hostname part of the HTTP Host header. That is, the domain or IP address at which the server received the request, without the port number. Useful for returning different content depending on which URL your visitors use to access the server. Shortcut for request.url.hostname.

To get the host, which includes the port number, see request.host.

request.href

Type: string
Example: 'http://localhost:3000/page.html?query'

The full URL associated with the request, represented as a string. Shortcut for request.url.href.

To get this value as a parsed object instead, use request.url.

request.method

Type: string
Example: 'GET'

The HTTP method associated with the request, such as GET or POST.

request.origin

Type: string
Example: 'http://localhost:3000'

The scheme and host parts of the request URL. Shortcut for request.url.origin.

request.params

Type: object

Contains the name/value pairs of path parameters, where each key is a parameter name from the route path and the value is the corresponding part of the request path. Shortcut for request.route.params.

request.path

Type: string
Example: /page.html

The path part of the request URL, excluding the query. Shortcut for request.url.pathname.

request.raw

Type: ServerRequest

The original request object from Deno’s http module, upon which many of the other request properties are based.

You probably don’t need this. It is provided as an escape hatch, but using it is not recommended.

request.referrer

Type: string

The value of the HTTP Referer header, which is useful for determining where the request came from. However, not all user agents send a referrer and the value can be influenced by various mechanisms, such as Referrer-Policy. As such, it is recommended to use the referrer as a hint, rather than relying on it directly.

Note that this property uses the correct spelling of “referrer”, unlike the header. It will be an empty string if the header is missing.

request.response

Type: Response

The response that will be sent for the request. To create a new response, see h.response().

request.route

Type: object

The route that is handling the request, as given to server.route(), with the following additional properties:

  • params is an object with properties for each dynamic path parameter
  • segments is an array of path parts, as in the values separated by / slashes in the route path

request.search

Type: string
Example: '?query'

The query part of the request URL, represented as a string. Shortcut for request.url.search.

To get this value as a parsed object instead, use request.searchParams.

request.searchParams

Type: URLSearchParams

The query part of the request URL, represented as an object that has methods for working with the query parameters. Shortcut for request.url.searchParams.

To get this value as a string instead, use request.search.

request.server

Type: Server

The server that is handling the request.

request.state

Type: object

Contains the name/value pairs of the HTTP Cookie header, which is useful for keeping track of state across requests, e.g. to keep a user logged in.

request.url

Type: URL

The full URL associated with the request, represented as an object that contains properties for various parts of the URL,

To get this value as a string instead, use request.href. In some cases, the URL object itself can be used as if it were a string, because it has a smart .toString() method.

Response

The response object represents an HTTP response to the associated request that is passed to route handlers. You can access it as request.response or create a new response with the Response Toolkit by calling h.response(). It has utility methods that make it easy to modify the headers, status code, and other attributes.

response.body

Type: string | object | Uint8Array | Reader

The body that will be sent in the response. Can be updated by returning a value from the route handler or by creating a new response with h.response() and giving it a value.

response.code(statusCode)

Sets the response status code. When possible, it is better to use a more specific method instead, such as response.created() or response.redirect().

Returns the response so other methods can be chained.

Tip: Use Deno’s status constants to define the status code.

import { Status as status } from 'https://deno.land/std/http/http_status.ts';
const handler = (request, h) => {
    return h.response().code(status.Teapot);
};

response.created(url?)

Sets the response status to 201 Created and sets the Location header to the value of url, if provided.

Returns the response so other methods can be chained.

response.header(name, value)

Sets a response header. Always replaces any existing header of the same name. Headers are case insensitive.

Returns the response so other methods can be chained.

response.headers

Type: Headers

Contains the HTTP headers that will be sent in the response, such as Location, Vary, and others.

response.location(url)

Sets the Location header on the response to the value of url. When possible, it is better to use a more specific method instead, such as response.created() or response.redirect().

Returns the response so other methods can be chained.

response.permanent()

Only available after calling the response.redirect() method.

Sets the response status to 301 Moved Permanently or 308 Permanent Redirect based on whether the existing status is considered rewritable (see “method handling” on Redirections in HTTP for details).

Returns the response so other methods can be chained.

response.redirect(url)

Sets the response status to 302 Found and sets the Location header to the value of url.

Also causes some new response methods to become available for customizing the redirect behavior:

Returns the response so other methods can be chained.

response.rewritable(isRewritable?)

Only available after calling the response.redirect() method.

Sets the response status to 301 Moved Permanently or 302 Found based on whether the existing status is a permanent or temporary redirect code. If isRewritable is false, then the response status will be set to 307 Temporary Redirect or 308 Permanent Redirect.

Returns the response so other methods can be chained.

response.state(name, value)

Sets the Set-Cookie header to create a cookie with the given name and value. Cookie options can be specified by using an object for value. See Deno’s cookie interface for the available options.

Returns the response so other methods can be chained.

All of the following forms are supported:

response.state('color', 'blue');
response.state('color', { value : 'blue' });
response.state({ name : 'color', value : 'blue' });

response.status

Type: number
Example: 418

The status code that will be sent in the response. Defaults to 200, which means the request succeeded. 4xx and 5xx codes indicate an error.

response.temporary()

Only available after calling the response.redirect() method.

Sets the response status to 302 Found or 307 Temporary Redirect based on whether the existing status is considered rewritable (see “method handling” on Redirections in HTTP for details).

Returns the response so other methods can be chained.

response.type(mediaType)

Sets the Content-Type header on the response to the value of mediaType.

Overrides the media type that is set automatically by the framework.

Returns the response so other methods can be chained.

response.unstate(name)

Sets the Set-Cookie header to clear the cookie given by name.

Returns the response so other methods can be chained.

Response Toolkit

The response toolkit is an object that is passed to route handlers, with utility methods that make it easy to modify the response. For example, you can use it to set headers or a status code.

By convention, this object is assigned to a variable named h in code examples.

h.redirect(url)

Creates a new response with a redirect status. Shortcut for h.response().redirect(url). See response.redirect() for details.

Returns the response so other methods can be chained.

h.response(body?)

Creates a new response with an optional body. This is the same as returning the body directly from the route handler, but it is useful in order to begin a chain with other response methods.

Returns the response so other methods can be chained.

Router

Documentation: Routing

A router is used to store and lookup routes. The server has a built-in router at server.router, which it uses to match an incoming request to a route handler function that generates a response. You can use the server’s router directly or you can create a custom router with pogo.router().

To copy routes from one router to another, see router.add(). You can pass a custom router to server.route() or server.router.add() to copy its routes into the server’s built-in router, thus making those routes available to incoming requests.

Note that you don’t necessarily need to create a custom router. You only need to create your own router if you prefer the chaining syntax for defining routes and you want to export the routes from a file that doesn’t have access to the server. In other words, a custom router is useful for larger applications.

const server = pogo.server();
server.router
    .get('/', () => {
        return 'Hello, World!';
    })
    .get('/status', () => {
        return 'Everything is swell!';
    });
const router = pogo.router()
    .get('/', () => {
      return 'Hello, World!';
    })
    .get('/status', () => {
      return 'Everything is swell!';
    });

const server = pogo.server();
server.route(router);

router.add(route, options?, handler?)

Adds one or more routes to the routing table, which makes them available for lookup, e.g. by a server trying to match an incoming request to a handler function.

The route argument can be:

  • A route object with optional properties for method, path, and handler
    • method is an HTTP method string or array of strings
    • path is a URL path string
    • handler is a function
  • A string, where it will be used as the path
  • A Router instance, where its routing table will be copied
  • An array of the above types

The options argument can be a route object (same as route) or a function, where it will be used as the handler.

The handler function can be a property of a route object, a property of the options object, or it can be a standalone argument.

Each argument has higher precedence than the previous argument, allowing you to pass in a route but override its handler, for example, by simply passing a handler as the final argument.

Returns the router so other methods can be chained.

const router = pogo.router().add('/', { method : '*' }, () => 'Hello, World!');

router.all(route, options?, handler?)

Shortcut for router.add(), with '*' as the default HTTP method.

Returns the router so other methods can be chained.

const router = pogo.router().all('/', () => 'Hello, World!');

router.delete(route, options?, handler?)

Shortcut for router.add(), with 'DELETE' as the default HTTP method.

Returns the router so other methods can be chained.

const router = pogo.router().delete('/', () => 'Hello, World!');

router.get(route, options?, handler?)

Shortcut for router.add(), with 'GET' as the default HTTP method.

Returns the router so other methods can be chained.

const router = pogo.router().get('/', () => 'Hello, World!');

router.lookup(method, path)

Look up a route that matches the given method and path.

Returns the route object with an additional params property that contains path parameter names and values.

router.patch(route, options?, handler?)

Shortcut for router.add(), with 'PATCH' as the default HTTP method.

Returns the router so other methods can be chained.

const router = pogo.router().patch('/', () => 'Hello, World!');

router.post(route, options?, handler?)

Shortcut for router.add(), with 'POST' as the default HTTP method.

Returns the router so other methods can be chained.

const router = pogo.router().post('/', () => 'Hello, World!');

router.put(route, options?, handler?)

Shortcut for router.add(), with 'PUT' as the default HTTP method.

Returns the router so other methods can be chained.

const router = pogo.router().put('/', () => 'Hello, World!');

router.routes

Type: object

The routing table, which contains all of the routes that have been added to the router.

Contributing

See our contributing guidelines for more details.

  1. Fork it.
  2. Make a feature branch: git checkout -b my-new-feature
  3. Commit your changes: git commit -am 'Add some feature'
  4. Push to the branch: git push origin my-new-feature
  5. Submit a pull request.

License

MPL-2.0 Š Seth Holladay

Go make something, dang it.