The Standard Router | Zend_Controller Programmer's Reference Guide | Action Controllers

# The Dispatcher

# Overview

Dispatching is the process of taking the request object, Zend_Controller_Request_Abstract, extracting the module name, controller name, action name, and optional parameters contained in it, and then instantiating a controller and calling an action of that controller. If any of the module, controller, or action are not found, it will use default values for them. Zend_Controller_Dispatcher_Standard specifies index for each of the controller and action defaults and default for the module default value, but allows the developer to change the default values for each using the setDefaultController(), setDefaultAction(), and setDefaultModule() methods, respectively.

> Note: Default Module
> When creating modular applications, you may find that you want your default module namespaced as well (the default configuration is that the default module is not namespaced). As of 1.5.0, you can now do so by specifying the prefixDefaultModule as `TRUE` in either the front controller or your dispatcher:

> 1. // In your front controller:
> 2. $front->setParam('prefixDefaultModule', true);
> 4. // In your dispatcher:
> 5. $dispatcher->setParam('prefixDefaultModule', true);
> This allows you to re-purpose an existing module to be the default module for an application.

Dispatching happens in a loop in the front controller. Before dispatching occurs, the front controller routes the request to find user specified values for the module, controller, action, and optional parameters. It then enters a dispatch loop, dispatching the request.

At the beginning of each iteration, it sets a flag in the request object indicating that the action has been dispatched. If an action or pre or postDispatch plugin resets that flag, the dispatch loop will continue and attempt to dispatch the new request. By changing the controller and/or action in the request and resetting the dispatched flag, the developer may define a chain of requests to perform.

The action controller method that controls such dispatching is _forward(); call this method from any of the preDispatch(), postDispatch() or action methods, providing an action, controller, module, and optionally any additional parameters you may wish to send to the new action:

1. public function fooAction()
2. {
3. // forward to another action in the current controller and module:
4. $this->_forward('bar', null, null, array('baz' => 'bogus'));
5. }
7. public function barAction()
8. {
9. // forward to an action in another controller:
10. // FooController::bazAction(),
11. // in the current module:
12. $this->_forward('baz', 'foo', null, array('baz' => 'bogus'));
13. }
15. public function bazAction()
16. {
17. // forward to an action in another controller in another module,
18. // Foo_BarController::bazAction():
19. $this->_forward('baz', 'bar', 'foo', array('baz' => 'bogus'));
20. }

# Subclassing the Dispatcher

Zend_Controller_Front will first call the router to determine the first action in the request. It then enters a dispatch loop, which calls on the dispatcher to dispatch the action.

The dispatcher needs a variety of data in order to do its work - it needs to know how to format controller and action names, where to look for controller class files, whether or not a provided module name is valid, and an API for determining if a given request is even dispatchable based on the other information available.

Zend_Controller_Dispatcher_Interface defines the following methods as required for any dispatcher implementation:

1. interface Zend_Controller_Dispatcher_Interface
2. {
3. /**
4. * Format a string into a controller class name.
5. *
6. * @param string $unformatted
7. * @return string
8. */
9. public function formatControllerName($unformatted);
11. /**
12. * Format a string into an action method name.
13. *
14. * @param string $unformatted
15. * @return string
16. */
17. public function formatActionName($unformatted);
19. /**
20. * Determine if a request is dispatchable
21. *
22. * @param Zend_Controller_Request_Abstract $request
23. * @return boolean
24. */
25. public function isDispatchable(
26. Zend_Controller_Request_Abstract $request
27. );
29. /**
30. * Set a user parameter (via front controller, or for local use)
31. *
32. * @param string $name
33. * @param mixed $value
34. * @return Zend_Controller_Dispatcher_Interface
35. */
36. public function setParam($name, $value);
38. /**
39. * Set an array of user parameters
40. *
41. * @param array $params
42. * @return Zend_Controller_Dispatcher_Interface
43. */
44. public function setParams(array $params);
46. /**
47. * Retrieve a single user parameter
48. *
49. * @param string $name
50. * @return mixed
51. */
52. public function getParam($name);
54. /**
55. * Retrieve all user parameters
56. *
57. * @return array
58. */
59. public function getParams();
61. /**
62. * Clear the user parameter stack, or a single user parameter
63. *
64. * @param null|string|array single key or array of keys for
65. * params to clear
66. * @return Zend_Controller_Dispatcher_Interface
67. */
68. public function clearParams($name = null);
70. /**
71. * Set the response object to use, if any
72. *
73. * @param Zend_Controller_Response_Abstract|null $response
74. * @return void
75. */
76. public function setResponse(
77. Zend_Controller_Response_Abstract $response = null
78. );
80. /**
81. * Retrieve the response object, if any
82. *
83. * @return Zend_Controller_Response_Abstract|null
84. */
85. public function getResponse();
87. /**
88. * Add a controller directory to the controller directory stack
89. *
90. * @param string $path
91. * @param string $args
92. * @return Zend_Controller_Dispatcher_Interface
93. */
94. public function addControllerDirectory($path, $args = null);
96. /**
97. * Set the directory (or directories) where controller files are
98. * stored
99. *
100. * @param string|array $dir
101. * @return Zend_Controller_Dispatcher_Interface
102. */
103. public function setControllerDirectory($path);
105. /**
106. * Return the currently set directory(ies) for controller file
107. * lookup
108. *
109. * @return array
110. */
111. public function getControllerDirectory();
113. /**
114. * Dispatch a request to a (module/)controller/action.
115. *
116. * @param Zend_Controller_Request_Abstract $request
117. * @param Zend_Controller_Response_Abstract $response
118. * @return Zend_Controller_Request_Abstract|boolean
119. */
120. public function dispatch(
121. Zend_Controller_Request_Abstract $request,
122. Zend_Controller_Response_Abstract $response
123. );
125. /**
126. * Whether or not a given module is valid
127. *
128. * @param string $module
129. * @return boolean
130. */
131. public function isValidModule($module);
133. /**
134. * Retrieve the default module name
135. *
136. * @return string
137. */
138. public function getDefaultModule();
140. /**
141. * Retrieve the default controller name
142. *
143. * @return string
144. */
145. public function getDefaultControllerName();
147. /**
148. * Retrieve the default action
149. *
150. * @return string
151. */
152. public function getDefaultAction();
153. }

In most cases, however, you should simply extend the abstract class Zend_Controller_Dispatcher_Abstract, in which each of these have already been defined, or Zend_Controller_Dispatcher_Standard to modify functionality of the standard dispatcher.

Possible reasons to subclass the dispatcher include a desire to use a different class or method naming schema in your action controllers, or a desire to use a different dispatching paradigm such as dispatching to action files under controller directories (instead of dispatching to class methods).

The Standard Router | Zend_Controller Programmer's Reference Guide | Action Controllers