README
citizen 0.9.x
citizen is an MVC-based web application framework designed for people who are more interested in quickly building fast, scalable apps than digging around Node's guts or cobbling together a Jenga tower made out of 20 different packages.
Use citizen as a foundation for a traditional server-side web application, a modular single-page app, or a REST API.
Benefits
- High performance and stability
- Zero-configuration server-side routing with SEO-friendly URLs
- Built-in session management
- Built-in caching of routes, individual controllers, objects, and static files
- Directives that make it easy to manage cookies, sessions, redirects, caches, and more
- Controller-based includes and chaining for powerful code reuse options
- HTML, JSON, and JSONP served from the same pattern
- Support for many template engines
- Few direct dependencies
New for 0.9.x
async await
and vanillareturn
statements replace event emitter controller actions- Hot module reloading in development mode—no more restarting the app while coding
citizen's API is stabilizing, but it's still subject to change. Always consult the change log before upgrading. Version 0.9.x has significant breaking changes compared to 0.8.x.
Have questions, suggestions, or need help? Send me an e-mail. Want to contribute? Pull requests are welcome.
Want to see citizen in action?
I use it on originaltrilogy.com. We get a moderate amount of traffic (averaging ~400k page views per month and peaking at 750k) and the site runs for months on end without the app/process crashing. It's very stable.
Quick Start
These commands will create a new directory for your web app, install citizen, use its scaffolding utility to create the app's skeleton, and start citizen with the web server listening on port 8080 (citizen defaults to port 80, but it's often in use already, so change it to whatever you want):
$ mkdir mywebapp
$ cd mywebapp
$ npm install citizen
$ node node_modules/citizen/util/scaffold skeleton -n 8080
$ node app/start.js
If everything went well, you'll see confirmation in the console that citizen is listening on the specified port. Go to http://127.0.0.1:8080 in your browser and you'll see a bare index template.
citizen installs Handlebars as its default template engine, but you can install any template engine supported by consolidate.js, update the config template settings, and modify the default view templates accordingly.
For configuration options, see Configuration. For more utilities to help you get started, see Utilities.
App Directory Structure
/app
/config // These files are all optional
citizen.json // Default config file
local.json // Examples of environment configs
qa.json
prod.json
/hooks // Application event hooks (optional)
application.js
request.js
response.js
session.js
/logs // Log files created by citizen and your app
app.log
citizen.log
/patterns
/controllers // Controllers
index.js
/models // Models (optional)
index.js
/views
/error
error.hbs // Default error view
/index
index.hbs // Default index view
other.hbs // Alternate index view (optional)
start.js
/web // public static assets
Initializing citizen and starting the web server
The start.js file in your app directory can be as simple as this:
// start.js
global.app = require('citizen')
app.start()
Run start.js from the command line:
$ node start.js
Configuration
The config directory is optional and contains configuration files that drive both citizen and your app in JSON format. You can have multiple citizen configuration files within this directory, allowing different configurations based on environment. citizen retrieves its configuration file from this directory based on the following logic:
- citizen parses each JSON file looking for a
host
key that matches the machine's hostname. If it finds one, it loads that configuration. - If it can't find a matching
host
key, it looks for a file named citizen.json and loads that configuration. - If it can't find citizen.json or you don't have a config directory, it runs under its default configuration.
Let's say you want to run citizen on port 8080 in your local dev environment and you have a local database your app will connect to. You could create a config file called local.json (or myconfig.json, whatever you want) with the following:
{
"host": "My-MacBook-Pro.local",
"citizen": {
"mode": "development",
"http": {
"port": 8080
}
},
"db": {
"server": "localhost",
"username": "dbuser",
"password": "dbpassword"
}
}
This config would extend the default configuration only when running on your local machine. If you were to push this to a production environment accidentally, it wouldn't do anything. Using this method, you can commit multiple config files from different environments to the same repository.
The database settings would be accessible within your app via app.config.db
. The citizen
and host
nodes are reserved for the framework; create your own node(s) to store your custom settings.
Inline config
You can also pass your app's configuration directly to citizen through app.start()
. If there is a config file, an inline config will extend the config file. If there's no config file, the inline configuration extends the default citizen config.
// Start an HTTP server on port 8080 accepting requests at www.mysite.com
app.start({
citizen: {
http: {
hostname: 'www.mysite.com',
port: 8080
}
}
})
// Start an HTTPS server with key and cert PEM files
app.start({
citizen: {
http: {
enable: false
},
https: {
enable: true,
key: '/absolute/path/to/key.pem',
cert: '/absolute/path/to/cert.pem'
}
}
})
// Start an HTTPS server with a PFX file running on port 3000,
// and add a custom namespace for your app's database config
app.start({
citizen: {
http: {
enable: false
},
https: {
enable: true,
port: 3000,
pfx: '/absolute/path/to/site.pfx'
}
},
db: {
server: "localhost", // app.config.db.server
username: "dbuser", // app.config.db.username
password: "dbpassword" // app.config.db.password
}
})
Default configuration
The following represents citizen's default configuration, which is extended by your configuration:
{
host : "",
citizen: {
mode : "production",
http: {
enable : true,
hostname : "127.0.0.1",
port : 80
},
https: {
enable : false,
hostname : "127.0.0.1",
port : 443,
secureCookies : true
},
connectionQueue : null,
fallbackController : "",
templateEngine : "handlebars",
compression: {
enable : false,
force : false,
mimeTypes : "text/plain text/html text/css application/x-javascript application/javascript text/xml application/xml application/xml+rss text/javascript image/svg+xml"
},
sessions : false,
sessionTimeout : 20,
layout: {
controller : "",
view : ""
},
legalFormat: {
html : true,
json : false,
jsonp : false
},
form: {},
cache: {
application: {
enable : true,
lifespan : 15,
resetOnAccess : true,
overwrite : false,
encoding : "utf-8",
synchronous : false
},
static: {
enable : false,
lifespan : 15,
resetOnAccess : true
},
control : {}
},
log: {
console: {
colors : true,
error : false,
status : false
},
file: {
error : false,
status : false,
maxFileSize : 10000,
watcher: {
interval : 60000
}
}
},
development: {
debug: {
scope: {
config : true,
context : true,
cookie : true,
form : true,
payload : true,
request : true,
response : true,
route : true,
session : true,
url : true,
},
depth : 3,
showHidden : false,
view : false
},
enableCache : false,
watcher: {
custom : [],
interval : 500,
killSession : false
}
},
urlPaths: {
app : "/"
},
directories: {
app : "[resolved based on location of start.js]",
hooks : "[directories.app]/hooks",
logs : "[directories.app]/logs",
controllers : "[directories.app]/patterns/controllers",
models : "[directories.app]/patterns/models",
views : "[directories.app]/patterns/views",
web : "web"
}
}
}
HTTPS
When starting an HTTPS server, in addition to the hostname
and port
options, citizen takes the same options as Node's https.createServer() (which takes the same options as tls.createServer()).
The only difference is how you pass key files. As you can see in the examples above, you pass citizen the file paths for your key files. citizen reads the files for you.
Config settings
Here's a complete rundown of citizen's settings and what they mean:
Setting | Values | Description |
---|---|---|
host
|
The operating system's hostname |
To load different config files in different environments, citizen relies upon the server's hostname as a key. At startup, if citizen finds a config file with a host key that matches the server's hostname, it chooses that config file. This is different from the HTTP hostname setting under the citizen node (see below).
|
citizen | ||
mode
|
Default: |
The application mode determines certain runtime behaviors. Production mode silences console logs and enables all application features. Development mode enables verbose console logs, disables caching, and enables the file watcher for hot module reloading for controllers, models, and hooks. |
http | ||
enable
|
Boolean
Default: |
This setting controls the HTTP server, which is enabled by default. |
hostname
|
String
Default: |
The hostname at which your app can be accessed via HTTP. The default is localhost, but you can specify an empty string to accept requests at any hostname. |
port
|
Number
Default: |
The port number on which citizen's HTTP server should listen for requests. |
https | ||
enable
|
Boolean
Default: |
This setting controls the HTTPS server, which is disabled by default. |
hostname
|
String
Default: |
The hostname at which your app can be accessed via HTTPS. The default is localhost, but you can specify an empty string to accept requests at any hostname. |
port
|
Number
Default: |
The port number on which citizen's HTTPS server should listen for requests. |
secureCookies
|
Boolean
Default: |
By default, all cookies set during an HTTPS request are secure. Set this option to false to override that behavior, making all cookies insecure and requiring you to manually set the secure option in the cookie directive.
|
connectionQueue
|
A positive integer
Default: |
The maximum number of incoming requests to queue. If left unspecified, the operating system determines the queue limit. |
sessions
|
Boolean
Default: |
Enables the user session scope, which assigns each visitor a unique ID and allows you to store data associated with that ID on the server. |
sessionTimeout
|
Positive integer
Default: |
If sessions are enabled, this number represents the length of a user's session in minutes. Sessions automatically expire if a user has been inactive for this amount of time. |
layout | ||
controller
|
String Default: (empty) |
If you use a global layout controller, you can specify the name of that controller here instead of using the handoff directive in all your controllers. |
view
|
String Default: (empty) |
By default, the layout controller will use the default layout view, but you can specify a different view here. Use the file name without the file extension. |
templateEngine
|
String
Default: |
citizen installs Handlebars by default, but you can change the template engine to any engine supported by consolidate.js. |
legalFormat | ||
html
|
Boolean
Default: |
citizen provides HTML output by default based on your views. You can disable HTML entirely if you plan to use citizen for building an API that returns JSON or JSONP only. |
json
|
Boolean
Default: |
JSON output is disabled by default. Set this value to true to enable global JSON output from all controllers. To enable JSON at the controller action level, see the legalFormat directive and JSON and JSONP for details.
|
jsonp
|
Boolean
Default: |
JSONP output is disabled by default. Set this value to true to enable global JSONP output from all controllers. To enable JSONP at the controller action level, see the legalFormat directive and JSON and JSONP for details.
|
form | ||
{ options }
|
Object Default: Same as formidable |
citizen uses formidable to parse form data. The defaults match that of formidable. Provide settings in the form node to set default settings for all your forms. See Forms for details. |
compression | ||
enable
|
Boolean
Default: |
Enables gzip and deflate compression for rendered views and static assets. |
force
|
Boolean or String
Default: |
Forces gzip or deflate encoding for all clients, even if they don't report accepting compressed formats. Many proxies and firewalls break the Accept-Encoding header that determines gzip support, and since all modern clients support gzip, it's usually safe to force it by setting this to gzip , but you can also force deflate .
|
mimeTypes
|
String |
A space-delimited list of MIME types that should be compressed if compression is enabled. See the sample config above for the default list. If you want to add or remove items, you must replace the list in its entirety. |
cache | ||
application | ||
enable
|
Boolean
Default: |
Enables the in-memory cache, accessed via the cache.set() and cache.get() methods. Set this to false to disable the cache when in production mode, which is useful for debugging when not in development mode.
|
lifespan
|
Number
Default: |
The length of time a cached application asset remains in memory, in minutes. |
resetOnAccess
|
Boolean
Default: |
Determines whether to reset the cache timer on a cached asset whenever the cache is accessed. When set to false , cached items expire when the lifespan is reached.
|
overwrite
|
Boolean
Default: |
Determines whether a call to cache.set() will overwrite an existing cache key. By default, an error is thrown if the cache key already exists. You can either pass the overwrite flag as an option in cache.set() or set this to true to always overwrite.
|
encoding
|
String
Default: |
When you pass a file path to cache.set(), the encoding setting determines what encoding should be used when reading the file. |
synchronous
|
Boolean
Default: |
When you pass a file path to cache.set(), this setting determines whether the file should be read synchronously or asynchronously. By default, file reads are asynchronous. |
static | ||
enable
|
Boolean
Default: |
When serving static files, citizen normally reads the file from disk for each request. You can speed up static file serving considerably by setting this to true , which caches file buffers in memory.
|
lifespan
|
Number
Default: |
The length of time a cached static asset remains in memory, in minutes. |
resetOnAccess
|
Boolean
Default: |
Determines whether to reset the cache timer on a cached static asset whenever the cache is accessed. When set to false , cached items expire when the lifespan is reached.
|
control
|
Key/value pairs
Default: |
Use this setting to set Cache-Control headers for static assets. The key is the pathname of the asset, and the value is the Cache-Control header. See Client-Side Caching for details. |
log | ||
console | ||
colors
|
Boolean
Default: |
Enables color coding in console logs. |
error
|
Boolean
Default: |
Controls whether errors should be logged to the console. |
status
|
Boolean
Default: |
Controls whether status messages should be logged to the console when in production mode. (Development mode always logs to the console.) |
file | ||
error
|
Boolean
Default: |
Controls whether errors should be logged to a file. |
status
|
Boolean
Default: |
Controls whether status messages should be logged to a file. Applies to both development and production modes. |
maxFileSize
|
Number
Default: |
Determines the maximum file size of log files in kilobytes. Default is 10000 (10 megs). When the limit is reached, the log file is renamed and a new log file is created. |
watcher | ||
interval
|
Number
Default: |
For operating systems that don't support file events, this timer (in milliseconds) determines how often log files will be polled for changes prior to archiving. |
development | ||
debug | ||
scope
|
Object |
This setting determines which scopes are logged in the debug output in development mode. By default, all scopes are enabled. |
depth
|
Positive integer
Default: |
When citizen dumps an object in the debug content, it inspects it using Node's util.inspect. This setting determines the depth of the inspection, meaning the number of nodes that will be inspected and displayed. Larger numbers mean deeper inspection and slower performance. |
view
|
Boolean
Default: |
Set this to true to dump debug info directly into the HTML view. |
enableCache
|
Boolean
Default: |
Development mode disables the cache. Change this setting to true to enable the cache in development mode.
|
watcher | ||
custom
|
Array |
You can tell citizen's hot module reloader to watch your own custom modules. This array can contain objects with watch (relative directory path to your modules within the app directory) and assign (the variable to which you assign these modules) properties. Example:
[ { "watch": "/toolbox", "assign": "app.toolbox" } ]
|
interval
|
Number
Default: |
Determines the polling interval in milliseconds for hot module reloading on operating systems that don't support file system events. Shorter intervals are more CPU intensive. |
urlPaths | ||
app
|
String
Default: |
Denotes the URL path leading to your app. If you want your app to be accessible via http://yoursite.com/my/app and you're not using another server as a front end to proxy the request, this setting should be /my/app (don't forget the leading slash). This setting is required for the router to work.
|
These settings are exposed publicly via app.config.host
and app.config.citizen
.
Note: This documentation assumes your global app variable name is "app", but you can call it whatever you want. Adjust accordingly.
citizen methods and objects
app.start()
|
Starts a citizen web application server. |
app.cache.set() app.cache.exists() app.cache.get() app.cache.clear() app.log()
|
Helpers used internally by citizen, exposed publicly since you might find them useful. |
app.controllers app.models
|
Contains your supplied patterns, which you can use instead of require .
|
app.config
|
The configuration settings you supplied at startup |
Routing and URLs
The citizen URL structure determines which controller and action to fire, passes URL parameters, and makes a bit of room for SEO-friendly content that can double as a unique identifier. The structure looks like this:
http://www.site.com/controller/seo-content/action/myAction/param/val/param2/val2
For example, let's say your site's base URL is:
http://www.cleverna.me
The default controller is index
, so the above is the equivalent of the following:
http://www.cleverna.me/index
If you have an article
controller, you'd request it like this:
http://www.cleverna.me/article
Instead of query strings, citizen uses an SEO-friendly method of passing URL parameters consisting of name/value pairs. If you had to pass an article ID of 237 and a page number of 2, you'd append name/value pairs to the URL:
http://www.cleverna.me/article/id/237/page/2
Valid parameter names may contain letters, numbers, underscores, and dashes, but must start with a letter or underscore.
The default controller action is handler()
, but you can specify alternate actions with the action
parameter (more on this later):
http://www.cleverna.me/article/action/edit
citizen also lets you optionally insert relevant content into your URLs, like so:
http://www.cleverna.me/article/My-Clever-Article-Title/page/2
This SEO content must always follow the controller name and precede any name/value pairs. You can access it generically via route.descriptor
or within the url
scope (url.article
in this case), which means you can use it as a unique identifier (more on URL parameters in the Controllers section).
The SEO content can consist of letters, numbers, dots (.), and the tilde (~) character.
MVC Patterns
citizen relies on a simple model-view-controller convention. The article pattern mentioned above might use the following structure:
app/
patterns/
controllers/
article.js
models/
article.js
views/
article/ // Directory name matches the controller name
article.hbs // Default view name matches the controller name
edit.hbs // Secondary view, which must be called explicitly
At least one controller is required for a given URL, and a controller's default view directory and default view file must share its name. Additional views should reside in this same directory. More on views in the Views section.
Models and views are optional and don't necessarily need to be associated with a particular controller. If your controller doesn't need a model, you don't need to create one. If your controller is going to pass its output to another controller for further processing and final rendering, you don't need to include a matching view. (See the controller handoff directive.)
Controllers
A citizen controller is just a Node module. Each controller requires at least one public method to serve as an action for the requested route. The default action should be named handler()
, which is called by citizen when no action is specified in the URL.
// article controller
module.exports = {
handler: handler
}
// Default action
async function handler(params, context) {
// Do some stuff
return {
// Send content and directives to the server
}
}
The citizen server calls handler()
after it processes the initial request and passes it 2 arguments: an object containing the parameters of the request and the current request's context.
request |
The request object generated by the server, just in case you need direct access |
response |
The response object generated by the server |
route |
Details of the route, such as the requested URL and the name of the route (controller) |
url |
Any URL parameters that were passed including the descriptor, if provided |
form |
Data collected from a POST |
payload |
Data collected from a PUT |
cookie |
An object containing any cookies sent with the request |
session |
An object containing any session variables, if sessions are enabled |
In addition to having access to these objects within your controller, they are also included in your view context automatically so you can reference them within your view templates as local variables (more details in the Views section).
For example, based on the previous article URL...
http://www.cleverna.me/article/My-Clever-Article-Title/page/2
...you'll have the following params.url
object passed to your controller:
{
article: 'My-Clever-Article-Title',
page: '2'
}
The controller name becomes a property in the URL scope that references the descriptor, which makes it well-suited for use as a unique identifier. This content is also available in the params.route
object as route.descriptor
.
The context
argument contains any data that's been generated by the request up to this point. There are various events that can populate this argument with content and directives, which are then passed to your controller so you can access that content or see what directives have been set by previous events.
To return the results of the controller action, include a return
statement with any content and directives you want to pass to citizen.
Using the above URL parameters, I can retrieve the article content from the model and pass it back to the server:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
const author = await app.models.article.getAuthor({
author: article.author
})
// Return the article for view rendering using the content directive
return {
content: {
article: article,
author: author
}
}
}
Alternate actions can be requested using the action
URL parameter. For example, maybe we want a different action and view to edit an article:
// http://www.cleverna.me/article/My-Clever-Article-Title/page/2/action/edit
// article controller
module.exports = {
handler: handler,
edit: edit
}
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
const author = await app.models.article.getAuthor({
author: article.author
})
// Return the article for view rendering using the content directive
return {
content: {
article: article,
author: author
}
}
}
async function edit(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
// Use the /patterns/views/article/edit.hbs view for this action (more on
// alternate views in later sections).
return {
content: {
article: article
},
view: 'edit'
}
}
You place any data you want to pass back to citizen within the return
statement. All the content you want to render in your view should be passed to citizen within an object called content
, as shown above. Additional objects can be passed to citizen to set directives that provide instructions to the server (explained later in the Controller Directives section). You can even add your own objects to the request context and pass them from controller to controller (more in the Controller Handoff section.)
Private controllers
To make a controller private—inaccessible via HTTP, but accessible within your app—add a plus sign (+
) to the beginning of the file name:
app/
patterns/
controllers/
+_header.js // Partial, only accessible internally
_head.js // Partial, accessible via www.cleverna.me/_head
article.js // Accessible via www.cleverna.me/article
Cross domain requests
If you want to make a controller action available to third parties, see the CORS section.
Models
Models are optional and their structure is completely up to you. citizen doesn't talk to your models directly; it only stores them in app.models
for your convenience.
Here's what a simple model for the article pattern might look like:
// article model
module.exports = {
getArticle: getArticle
}
async function getArticle(article, page) {
const client = await app.db.connect()
const result = await client.query({
text: 'select title, summary, text, author, published from articles where id = $1 and page = $2;',
values: [ article, page ]
})
client.release()
return result.rows
}
async function getAuthor(author) {
const client = await app.db.connect()
const result = await client.query({
text: 'select name, email from users where id = $1;',
values: [ author ]
})
client.release()
return result.rows
}
Views
citizen installs Handlebars by default, but you can install any engine supported by consolidate.js and set the templateEngine
config setting accordingly. Make sure you use the correct file extension with your views so citizen knows how to parse them. citizen only supports one template engine at a time; you can't mix and match templates.
In article.hbs
, you can reference objects you placed within the content
object passed into the controller's return statement. citizen also injects the params
object into your view context automatically, so you have access to those objects as local variables (such as the url
scope):
{{! article.hbs }}
<!doctype html>
<html>
<body>
<main>
<h1>
{{article.title}} — Page {{url.page}}
</h1>
<h2>{{author.name}}, {{article.published}}</h2>
<p>
{{article.summary}}
</p>
<section>
{{article.text}}
</section>
</main>
</body>
</html>
Rendering alternate views
By default, the server renders the view whose name matches that of the controller. To render a different view, use the view
directive in your return statement.
JSON and JSONP
You can tell a controller to return its content as JSON by adding the format
URL parameter, letting the same resource serve both a complete HTML view and JSON for AJAX requests and RESTful APIs.
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/json
Returns...
{
"article": {
"title": "My Clever Article Title",
"summary": "Am I not terribly clever?",
"text": "This is my article text."
},
"author": {
"name": "John Smith",
"email": "jsmith@cleverna.me"
}
}
Whatever you've added to the controller's return statement content
object will be returned.
To enable JSON output at the controller level:
return {
content: {
article: article,
author: author
},
legalFormat: {
json: true
}
}
You can also specify indivdidual nodes to return instead of returning the entire content object by using the output
URL parameter:
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/json/output/author
Returns...
{
"name": "John Smith",
"email": "jsmith@cleverna.me"
}
Use dash notation in the output parameter to go deeper into the node tree:
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/json/output/author-email
Returns...
jsmith@cleverna.me
For JSONP, use format
paired with callback
in the URL:
http://www.cleverna.me/article/My-Clever-Article-Title/format/jsonp/callback/foo
Returns:
foo({
"article": {
"title": "My Clever Article Title",
"summary": "Am I not terribly clever?",
"text": "This is my article text."
},
"author": {
"name": "John Smith",
"email": "jsmith@cleverna.me"
}
})
To enable JSONP output at the controller level:
return {
legalFormat: {
jsonp: true
}
}
The output
URL parameter works with JSONP as well.
http://www.cleverna.me/article/My-Clever-Article-Title/page/2/format/jsonp/callback/foo/output/author-email
Returns...
foo("jsmith@cleverna.me")
Do you always want a particular controller action to return JSON without the URL flag? Simple:
async function handler(params) {
// All requests handled by this controller action will output JSON
params.route.format = 'json'
return {
content: {
article: article,
author: author
},
legalFormat: {
json: true
}
}
}
Are you building a RESTful API and want every request across all controllers to return JSON without using the URL flag? Also simple, via optional hooks such as request.js
:
// File: /app/hooks/request.js
// All requests will be returned in JSON format because this function runs
// at the beginning of every request. Learn more in the "Application Event Hooks
// and the Context Argument" section.
function start(params) {
// Set the output format to JSON
params.route.format = 'json'
return {
// Set JSON as a legal output format
legalFormat: {
json: true
}
}
}
JSON security risks
The JSON output from any controller action is driven by the returned content object. Anything you place in the content object will be present in the JSON output — whether it's present in the HTML view or not.
Take care not to place sensitive data in the content object thinking it will never be exposed because you don't reference it in your view template, because it WILL show up in your JSON.
Handling Errors
citizen does a great job of handling unexpected errors without exiting the process (and thereby crashing your server). The following controller action will throw an error, but the server will respond with a 500 and keep running:
async function handler(params, context) {
// app.models.article.foo() throws an error
const foo = await app.models.article.foo()
return {
content: foo
}
}
You can also throw an error manually and customize the error message:
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
// If everything is fine, return the content
if ( article ) {
return {
content: article
}
// If there's a problem, throw an error
} else {
let err = new Error('The requested article does not exist.')
// The default error code is 500, but you can specify a different code
err.statusCode = 404
throw err
}
}
Errors are returned in the format requested by the route. If you request JSON and the route throws an error, the error will be in JSON format.
The app skeleton created by the scaffold utility includes optional error view templates for common client and server errors, but you can create templates for any HTTP error code.
Error Views
To create custom error views for server errors, create a directory called /app/patterns/views/error
and populate it with templates named after the HTTP response code or Node error code.
app/
patterns/
views/
error/
404.hbs // Handles 404 errors
500.hbs // Handles 500 errors
ENOENT.hbs // Handles bad file read operations
error.hbs // Handles any error without its own template
These error views are only used when citizen is in production
mode. In development
mode, citizen dumps the raw error/stack to the view.
Controller Directives
In addition to the view content, the controller action's return statement can also pass directives to render alternate views, set cookies and session variables, initiate redirects, call and render includes, cache views (or entire routes), and hand off the request to another controller for further processing.
Alternate Views
By default, the server renders the view whose name matches that of the controller. To render a different view, use the view
directive in your return statement:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
return {
content: article,
// This tells the server to render app/patterns/views/article/edit.hbs
view: 'edit'
}
}
Formats
citizen returns HTML by default, and you can enable JSON or JSONP in the global config. However, if you want to enable custom formats at the controller action level, use the legalFormat
directive.
If you don't enable a format, either in the controller action or global config, trying to use that format will throw an error.
return {
legalFormat: {
html: false,
json: true,
jsonp: true
}
}
Cookies
You set cookies by returning a cookie
object within the controller action.
Here's an example of a complete cookie object's default settings:
cookie.foo = {
value: 'myValue',
// Valid expiration options are:
// 'now' - deletes an existing cookie
// 'never' - current time plus 30 years, so effectively never
// 'session' - expires at the end of the browser session (default)
// [time in minutes] - expires this many minutes from now
expires: 'session',
// By default, a cookie's path is the same as the app path in your config
path: app.config.citizen.urlPaths.app,
// citizen's cookies are accessible via HTTP only by default. To access a
// cookie via JavaScript, set this to false.
httpOnly: true,
// Cookies are insecure when set over HTTP and secure when set over HTTPS.
// You can override that behavior globally with the https.secureCookies setting
// in your config or on a case-by-case basis with this setting.
secure: false
}
The following sample login controller tells the server to set username
and passwordHash
cookies that expire in 20 minutes:
// login controller
module.exports = {
handler: handler
}
async function loginForm(params, context) {
let authenticate = await app.models.login.authenticate({
// Form values, just like URL parameters, are passed via the params
// argument
username: params.form.username,
password: params.form.password
}),
// If a directive is an empty object, that's fine. citizen just ignores it.
cookie = {}
if ( authenticate.success ) {
cookie = {
// The cookie gets its name from the property name
username: {
value: authenticate.username,
expires: 20
},
passwordHash: {
value: authenticate.passwordHash,
expires: 20
}
}
}
return {
content: {
authenticate: authenticate
},
cookie: cookie
}
}
Alternatively, you can pass strings into the cookie directive, which will create cookies using the default attributes. The following code sets the same cookies, but they expire at the end of the browser session:
return {
cookie: {
username: authenticate.username,
passwordHash: authenticate.passwordHash
}
}
Cookies sent by the client are available in params.cookie
within the controller and simply cookie
within the view context:
<!doctype html>
<html>
<body>
<section>
{{#if cookie.username}}
Welcome, {{cookie.username}}.
{{else}}
<a href="/login">Login</a>
{{/if}}
</section>
</body>
</html>
Cookie variables you set within your controller aren't immediately available within the params.cookie
scope. citizen has to receive the context from the controller before it can send the cookie to the client, so use a local instance of the variable if you need to access it during the same request.
Proxy Header
If you use citizen behind another web server, such as NGINX or Apache, you'll need to add a custom header called x-citizen-uri
for secure cookies to work correctly. This is because citizen only has access to the URI it receives in the proxy request, not the actual URI requested by the browser, which in the case of HTTPS requests will have a different protocol.
Here's an example of how you might set this up in NGINX:
location / {
proxy_set_header X-Real-IP $remote_addr
proxy_set_header Host $host
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for
proxy_set_header x-citizen-uri https://website.com$request_uri
proxy_pass http://127.0.0.1:8080
}
Session Variables
If sessions are enabled, you can access session variables via params.session
in your controller or simply session
within views. These local scopes reference the current user's session without having to pass a session ID.
By default, a session has four properties: id
, started
, expires
, and timer
. The session ID is also sent to the client as a cookie called ctzn_sessionID
.
Setting session variables is pretty much the same as setting cookie variables:
return {
session: {
username: 'Danny',
nickname: 'Doc'
}
}
Like cookies, session variables you've just assigned aren't available during the same request within the params.session
scope, so use a local instance if you need to access this data right away.
Sessions expire based on the sessionTimeout
config property, which represents the length of a session in minutes. The default is 20 minutes. The timer
is reset with each request from the user. When the timer
runs out, the session is deleted. Any client requests after that time will generate a new session ID and send a new session ID cookie to the client.
To forcibly clear and expire the current user's session:
return {
session: {
expires: 'now'
}
}
Redirects
You can pass redirect instructions to the server that will be initiated after the controller action is processed.
The redirect
object takes a URL string in its shorthand version, or three options: statusCode
, url
, and refresh
. If you don't provide a status code, citizen uses 302 (temporary redirect). The refresh
option determines whether the redirect uses a Location header or the non-standard Refresh header.
// Initiate a temporary redirect using the Location header
return {
redirect: 'http://cleverna.me/login'
}
// Initiate a permanent redirect using the Refresh header, delaying the redirect
// by 5 seconds
return {
redirect: {
url: 'http://cleverna.me/new-url',
statusCode: 301,
refresh: 5
}
}
Unlike the Location header, if you use the refresh
option, citizen will send a rendered view to the client because the redirect occurs client-side.
Using the Location header breaks (in my opinion) the Referer header because the Referer ends up being not the resource that initiated the redirect, but the resource prior to the page that initiated it. To get around this problem, citizen stores a session variable called ctzn_referer
that contains the URL of the resource that initiated the redirect, which you can use to redirect users properly. For example, if an unauthenticated user attempts to access a secure page and you redirect them to a login form, the address of the secure page will be stored in ctzn_referer
so you can send them there instead of the page containing the link to the secure page.
If you haven't enabled sessions, citizen falls back to creating a cookie named ctzn_referer
instead.
Proxy Header
If you use citizen behind another web server, such as NGINX or Apache, you'll need to add a custom header called x-citizen-uri
for citizen_referer
to work correctly. This is because citizen only has access to the URI it receives in the proxy request, not the actual URI requested by the browser. For example, using NGINX as an HTTPS front end means you'll have a different protocol in the requested URI than you'll have in the proxy URI. The x-citizen-uri
header ensures citizen receives the original requested URL intact.
Here's an example of how you might set this up in NGINX:
location / {
proxy_set_header X-Real-IP $remote_addr
proxy_set_header Host $host
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for
proxy_set_header x-citizen-uri https://website.com$request_uri
proxy_pass http://127.0.0.1:8080
}
HTTP Headers
You can set HTTP headers using the header
directive:
return {
header: {
'Cache-Control': 'max-age=86400',
'Date': new Date().toISOString()
}
}
Including Controllers
citizen lets you use complete MVC patterns as includes. These includes are more than just chunks of code that you can reuse because each has its own controller, model, and view(s). Here's the syntax:
async function handler(params, context) {
return {
include: {
// The include name referenced in your view gets its name from the
// property name. This include calls the _header controller with the
// default action and view.
header: {
controller: '_header'
},
// This include calls the _footer controller using the "myAction" action.
footer: {
controller: '_footer',
action: 'myAction'
},
// This include calls the _login-form controller using the "myAction"
// action and "myView" view.
loginForm: {
controller: '_login-form',
action: 'myAction',
view: 'myView'
},
// This include calls the index controller, but processes it as if it
// had been requested from a different URL. In this case, the include
// will return JSON.
index: {
route: '/index/format/json'
},
// This include calls the index controller, but processes it as if it
// had been requested from a different URL and uses an alternate view.
index: {
route: '/index/format/json',
view: 'myView'
}
}
}
}
Let's say our article pattern's template has the following contents. The head section contains dynamic meta data, and the header's content changes depending on whether the user is logged in or not:
<!doctype html>
<html>
<head>
<title>{{metaData.title}}</title>
<meta name="description" content="{{metaData.description}}">
<meta name="keywords" content="{{metaData.keywords}}">
<link rel="stylesheet" type="text/css" href="site.css">
</head>
<body>
<header>
{{#if cookie.username}}
<p>Welcome, {{cookie.username}}</p>
{{else}}
<a href="/login">Login</a>
{{/if}}
</header>
<main>
<h1>{{title}} — Page {{url.page}}</h1>
<p>{{summary}}</p>
<section>{{text}}</section>
</main>
</body>
</html>
It probably makes sense to use includes for the head section and header because you'll use that code everywhere, but rather than simple partials, you can create citizen includes. The head section can use its own model for populating the meta data, and since the header is different for authenticated users, let's pull that logic out of the view and put it in the header's controller. I like to follow the convention of starting partials with an underscore, but that's up to you:
app/
patterns/
controllers/
_head.js
_header.js // Doesn't pull data, so it doesn't need a model
article.js
models/
_head.js
article.js
views/
_head/
_head.hbs
_header/
_header.hbs
_header-authenticated.hbs // A different header for logged in users
article/
article.hbs
When the article controller is fired, it has to tell citizen which includes it needs. We do that with the include
directive:
// article controller
module.exports = {
handler: handler
}
async function handler(params, context) {
// Get the article
const article = await app.models.article.getArticle({
article: params.url.article,
page: params.url.page
})
return {
content: article,
include: {
head: {
// If only the controller is specified, the default action handler() is
// called and the default view is rendered (_head.hbs in this case).
controller: '_head'
},
header: {
controller: '_header',
// If the username cookie exists, use the authenticated action. If not,
// use handler.
action: params.cookie.username ? 'authenticated' : 'handler'
// You can also specify the view here like this:
// view: '_header-authenticated'
// But we'll do that in the header controller instead. If you do specify
// a view here, it will override whatever view is set in the controller.
}
}
}
}
citizen include patterns have the same requirements as regular patterns, including a controller with a public action. The include
directive above tells citizen to call the _head and _header controllers, pass them the same arguments that were passed to the article controller (params and context), render their respective views, and add the resulting views to the view context.
Here's what our head section controller might look like:
// _head controller
module.exports = {
handler: handler
}
async function handler(params, context) {
let metaData = await app.models._head({ article: params.url.article })
return {
content: metaData
}
}
And the head section view:
<head>
<title>{{title}}</title>
<meta name="description" content="{{description}}">
<meta name="keywords" content="{{keywords}}">
<link rel="stylesheet" type="text/css" href="site.css">
</head>
Here's what our header controller might look like:
// _header controller
module.exports = {
handler: handler,
authenticated: authenticated
}
function handler(params, context) {
return {
view: '_header'
}
}
function authenticated(params, context) {
return {
view: '_header-authenticated'
}
}
And the header views:
{{! _header view (/patterns/views/_header/_header.hbs) }}
<header>
<a href="/login">Login</a>
</header>
{{! _header-authenticated view (/patterns/views/_header/_header-authenticated.hbs) }}
<header>
<p>Welcome, {{cookie.username}}</p>
</header>
The rendered includes are stored in the include
scope. The include
object contains rendered HTML views, so you need to skip escaping ({{{...}}}
in Handlebars) within the article view:
{{! article.hbs }}
<!doctype html>
<html>
{{{include.head}}}
<body>
{{{include.header}}}
<main>
<h1>{{title}} — Page {{url.page}}</h1>
<p>{{summary}}</p>
<section>{{text}}</section>
</main>
</body>
</html>
citizen includes are self-contained. While they receive the same request context (URL parameters, form inputs, etc.) as the calling controller, content generated by the calling controller isn't automatically passed to its includes, and content generated inside an include isn't passed back to the caller. citizen includes also can't make use of cookie, session, redirect, or handoff directives, nor can they use their own includes (nested includes). Any of these directives within an include will be ignored. They only use the content directive (to populate their own views), the view directive for setting the view used by the include, and the cache directive for controller caching.
A pattern meant to be used as an include can be accessed via HTTP just like any other controller. You could request the _head
controller like so:
http://cleverna.me/_head
Perhaps you'd have it return meta data as JSON for the article pattern:
// http://cleverna.me/_head/article/My-Clever-Article-Title/format/json
{
"title": "My Clever Article Title",
"description": "My article's description.",
"keywords": "clever, article, keywords"
}
Of course, if you don't write the controller in a manner to accept direct requests and return content, it'll return nothing (or