flight-core/README.md

# What is Flight?

Flight is a fast, simple, extensible framework for PHP.
Flight enables you to quickly and easily build RESTful web applications.

    require 'flight/Flight.php';

    Flight::route('/', function(){
        echo 'hello world!';
    });

    Flight::start();

[Learn more](http://flightphp.com/learn)

# Requirements

Flight requires PHP 5.3 or greater. 

# License

Flight is released under the [MIT](http://www.opensource.org/licenses/mit-license.php) license.

# Installation

1\. [Download](https://github.com/mikecao/flight/tarball/master) and extract the Flight framework files to your web directory.

2\. Configure your webserver.

For *Apache*, edit your .htaccess file with the following:

    RewriteEngine On
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ index.php [QSA,L]

For *Nginx*, add the following to your server declaration:

    server {
        location / {
            try_files $uri $uri/ /index.php;
        }
    }

3\. Create your index.php file.

First include the framework.

    require 'flight/Flight.php';

Then define a route and assign a function to handle the request.

    Flight::route('/', function(){
        echo 'hello world!';
    });

Finally, start the framework.

    Flight::start();

# Routing 

Routing in Flight is done by matching a URL pattern with a callback function.

    Flight::route('/', function(){
        echo 'hello world!';
    });

The callback can be any object that is callable. So you can use a regular function:

    function hello(){
        echo 'hello world!';
    }

    Flight::route('/', 'hello');

Or a class method:

    class Greeting {
        public static function hello() {
            echo 'hello world!';
        }
    }

    Flight::route('/', array('Greeting','hello'));

Routes are matched in the order they are defined. The first route to match a request will be invoked.

## Method Routing

By default, route patterns are matched against all request methods. You can respond to specific
methods by placing an identifier before the URL.

    Flight::route('GET /', function(){
        echo 'I received a GET request.';
    });

    Flight::route('POST /', function(){
        echo 'I received a POST request.';
    });

You can also map multiple methods to a single callback by using a `|` delimiter:

    Flight::route('GET|POST /', function(){
        echo 'I received either a GET or a POST request.';
    });

Method specific routes have precedence over global routes.

## Regular Expressions

You can use regular expressions in your routes:

    Flight::route('/user/[0-9]+', function(){
        // This will match /user/1234
    });

## Named Parameters

You can specify named parameters in your routes which will be passed along to your callback function.

    Flight::route('/@name/@id', function($name, $id){
        echo "hello, $name ($id)!";
    });

You can also include regular expressions with your named parameters by using the `:` delimiter:

    Flight::route('/@name/@id:[0-9]{3}', function($name, $id){
        // This will match /bob/123
        // But will not match /bob/12345
    });

## Wildcards

Matching is only done on individual URL segments. If you want to match multiple segments you can use the `*` wildcard.

    Flight::route('/blog/*', function(){
        // This will match /blog/2000/02/01
    });

To route all requests to a single callback, you can do:

    Flight::route('*', function(){
        // Do something
    });

# Extending

Flight designed to be an extensible framework. The framework comes with a set of default methods and components, but it allows you to map your own methods, register your own classes, or even override existing classes and methods.

## Mapping Methods

To map your own custom method, you use the `map` function:

    // Map your method
    Flight::map('hello', function($name){
        echo "hello $name!";
    });

    // Call your custom method
    Flight::hello('Bob');

## Registering Classes

To register your own class, you use the `register` function:

    // Register your class
    Flight::register('user', 'User');

    // Get an instance of your class
    $user = Flight::user();

The register method also allows you to pass along parameters to your class constructor. So when you load your custom class, it will come pre-initialized. You can define the constructor parameters by passing in an additional array. Here's an example of loading a database connection:

    // Register class with constructor parameters
    Flight::register('db', 'Database', array('localhost','mydb','user','pass'));

    // Get an instance of your class
    // This will create an object with the defined parameters
    //
    //     new Database('localhost', 'test', 'user', 'pass');
    //
    $db = Flight::db();

If you pass in an additional callback parameter, it will be executed immediately after class construction. This allows you to perform any set up procedures for your new object. The callback function takes one parameter, an instance of the new object.

    // The callback will be passed the object that was constructed
    Flight::register('db', 'Database', array('localhost', 'mydb', 'user', 'pass'), function($db){
        $db->connect();
    });

By default, every time you load your class you will get a shared instance.
To get a new instance of a class, simply pass in `false` as a parameter:

    // Shared instance of User
    $shared = Flight::user();

    // New instance of User
    $new = Flight::user(false);

Keep in mind that mapped methods have precedence over registered classes. If you declare both
using the same name, only the mapped method will be invoked.

# Overriding

Flight allows you to override its default functionality to suit your own needs without having to modify any code.

For example, when Flight cannot match a URL to a route, it invokes the `notFound` method which sends a generic HTTP 404 response.
You can override this behavior by using the `map` method:

    Flight::map('notFound', function(){
        // Display custom 404 page
        include 'errors/404.html';
    });

Flight also has custom error handling which you can override:

    Flight::map('error', function($e){
        // Log error somewhere
        log_error($e);
    });

Flight also allows you to replace core components of the framework.
For example you can replace the default Router class with your own custom class:

    // Register your custom class
    Flight::register('router', 'MyRouter');

    // When Flight loads the Router instance, it will load your class
    $myrouter = Flight::router();

Framework methods like `map` and `register` however cannot be overridden. You will get an error if you try to do so.

# Filtering

Flight allows you to filter methods before and after they are called. There are no predefined hooks
you need to memorize. You can filter any of the default framework methods as well as any custom methods that
you've mapped.

A filter function looks like this:

    function(&$params, &$output) {
        // Filter code
    }

Using the passed in variables you can manipulate the input parameters and/or the output.

You can have a filter run before a method by doing:

    Flight::before('start', function(&$params, &$output){
        // Do something
    });

You can have a filter run after a method by doing:

    Flight::after('start', function(&$params, &$output){
        // Do something
    });

You can add as many filters as you want to any method. They will be called in the order
that they are declared.

Here's an example of the filtering process:

    // Map a custom method
    Flight::map('hello', function($name){
        return "Hello, $name!";
    });

    // Add a before filter
    Flight::before('hello', function(&$params, &$output){
        // Manipulate the parameter
        $params[0] = 'Fred';
    });

    // Add an after filter
    Flight::after('hello', function(&$params, &$output){
        // Manipulate the output
        $output .= " Have a nice day!";
    }

    // Invoke the custom method
    echo Flight::hello('Bob');

This should display:

    Hello Fred! Have a nice day! 

If you have defined multiple filters, you can break the chain by returning `false`:

    Flight::before('start', function(&$params, &$output){
        echo 'one';
    });

    Flight::before('start', function(&$params, &$output){
        echo 'two';

        // This will end the chain
        return false;
    });

    // This will not get called
    Flight::before('start', function(&$params, &$output){
        echo 'three';
    });

Note, core methods such as `map` and `register` cannot be filtered because they are called
directly and not invoked dynamically.

# Variables

Flight allows you to save variables so that they can be used anywhere in your application.

    // Save your variable
    Flight::set('id', 123);

    // Elsewhere in your application
    $id = Flight::get('id');

To see if a variable has been set you can do:

    if (Flight::has('id')) {
        // Do something
    }

You can clear a variable by doing:

    // Clears the id variable
    Flight::clear('id');

    // Clears all variables
    Flight::clear();

Flight also uses variables for configuration purposes.

    Flight::set('flight.log_errors', true);

# Views 

Flight provides some basic templating functionality by default. To display a view template call the `render` method with the name of the template file and optional template data:

    Flight::render('hello.php', array('name', 'Bob'));

The template data you pass in is automatically injected into the template and can be reference like a local variable. Template files are simply PHP files. If the content of the `hello.php` template file is:

    Hello, '<?php echo $name; ?>'!

The output would be:

    Hello, Bob!

You can also manually set view variables by using the set method:

    Flight::view()->set('name', 'Bob');

The variable `name` is now available across all your views. So you can simply do:

    Flight::render('hello');

Note that when specifying the name of the template in the render method, you can leave out the .php extension.

By default Flight will look for a `views` directory for template files. You can set an alternate path for your templates by setting the following config:

    Flight::set('flight.views.path', '/path/to/views');

## Layouts

It is common for websites to have a single layout template file with interchanging content. To render content for a layout you need to pass in a variable name to the `render` method.

    Flight::render('header', array('heading' => 'Hello'), 'header_content');
    Flight::render('body', array('message' => 'World'), 'body_content');

Your view will then have saved variables called `header_content` and `body_content`. You can then render your layout by doing:

    Flight::render('layout', array('title' => 'Home');

If the template file looks like this:

header.php:

    <h1><?php echo $heading; ?></h1>

body.php:

    <div><?php echo $body; ?></div>

layout.php:

    <html>
    <head>
    <title><?php echo $title; ?></title>
    </head>
    <body>
    <?php echo $header_content; ?>
    <?php echo $body_content; ?>
    </body>
    </html>

The output would be:

    <html>
    <head>
    <title>My Page</title>
    </head>
    <body>
    <h1>Hello</h1>
    <div>World</div>
    </body>
    </html>

## Custom Views

Flight allows you to swap out the default view engine simply by registering your own view class.
Here's how you would use the [Smarty](http://www.smarty.net/) template engine for your views:

    // Load Smarty library
    require './Smarty/libs/Smarty.class.php';

    // Register Smarty as the view class
    // Also pass a callback function to configure Smarty on load
    Flight::register('view', 'Smarty', array(), function($smarty){
        $smarty->template_dir = './templates/';
        $smarty->compile_dir = './templates_c/';
        $smarty->config_dir = './config/';
        $smarty->cache_dir = './cache/';
    });

    // Assign template data
    Flight::view()->assign('name', 'Bob');

    // Display the template
    Flight::view()->display('hello.tpl');

For completeness, you should also override Flight's default render method:

    Flight::map('render', function($template, $data){
        Flight::view()->assign($data);
        Flight::view()->display($template);
    });

# Error Handling 

## Errors and Exceptions

All errors and exceptions are caught by Flight and passed to the `error` method.
The default behavior is to send a generic HTTP `500 Internal Server Error` response with some error information.
You can override this behavior for your own needs:

    Flight::map('error', function(){
        // Handle error
    });

By default errors are not logged to the web server. You can enable this by changing the config:

    Flight::set('flight.log_errors', true);

## Not Found

When a URL can't be found, Flight calls the `notFound` method. The default behavior is to
send an HTTP `404 Not Found` response with a simple message. You can override this behavior for your own needs:

    Flight::map('notFound', function(){
        // Display custom error page
    });

# Redirects 

You can redirect the current request by using the `redirect` method and passing in a new URL:

    Flight::redirect('/new/location');

# HTTP Caching 

Flight provides built-in support for HTTP level caching. If the caching condition is met,
Flight will return an HTTP `304 Not Modified` response. The next time the client requests the same resource,
they will be prompted to use their locally cached version.

## Last-Modified

You can use the `lastModified` method and pass in a UNIX timestamp to set the date and time a page was last modified.
The client will continue to use their cache until the last modified value is changed.

    Flight::route('/news', function(){
        Flight::lastModified(1234567890);
        echo 'This content will be cached.';
    });

## ETag

ETag caching is similar to Last-Modified, except you can specify any id you want for the resource:

    Flight::route('/news', function(){
        Flight::etag('my-unique-id');
        echo 'This content will be cached.';
    });

Keep in mind that calling either `lastModified` or `etag` will both set and check the cache value.
If the cache value is the same between requests, Flight will immediately send the `304` response and stop
processing.

# Stopping 

You can stop the framework at any point by calling the `halt` method:

    Flight::halt();

You can also specify an optional HTTP status code and message:

    Flight::halt(200, 'Be right back...');

Calling `halt` will discard any response content up to that point.
If you want to stop the framework and output the current response, use the `stop` method:

    Flight::stop();