Filtering

Flight allows you to filter mapped 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:

/**
 * @param array $params The parameters passed to the method being filtered.
 * @param string $output (v2 output buffering only) The output of the method being filtered.
 * @return bool Return true/void or don't return to continue the chain, false to break the chain.
 */
function (array &$params, string &$output): bool {
  // 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 (array &$params, string &$output): bool {
  // Do something
});

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

Flight::after('start', function (array &$params, string &$output): bool {
  // 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 (string $name) {
  return "Hello, $name!";
});

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

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

// 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 in any of your filter functions:

Flight::before('start', function (array &$params, string &$output): bool {
  echo 'one';
  return true;
});

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

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

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

Note: Core methods such as map and register cannot be filtered because they are called directly and not invoked dynamically. See Extending Flight for more information.

• Extending Flight

• Make sure you are returning false from your filter functions if you want the chain to stop. If you don't return anything, the chain will continue.

• v2.0 - Initial Release.