Chapter 19 - Mastering Symfony's Configuration Files

Now that you know symfony very well, you are already able to dig into its code to understand its core design and discover new hidden abilities. But before extending the symfony classes to match your own requirements, you should take a closer look at some of the configuration files. Many features are already built into symfony and can be activated by just changing configuration settings. This means that you can tweak the symfony core behavior without overriding its classes. This chapter takes you deep into the configuration files and their powerful capabilities.

Symfony Settings

The frontend/config/settings.yml file contains the main symfony configuration for the frontend application. You have already seen the function of many settings from this file in the previous chapters, but let's revisit them.

As explained in Chapter 5, this file is environment-dependent, which means that each setting can take a different value for each environment. Remember that each parameter defined in this file is accessible from inside the PHP code via the sfConfig class. The parameter name is the setting name prefixed with sf_. For instance, if you want to get the value of the cache parameter, you just need to call sfConfig::get('sf_cache').

Default Modules and Actions

Symfony provides default pages for special situations. In the case of a routing error, symfony executes an action of the default module, which is stored in the sfConfig::get('sf_symfony_lib_dir')/controller/default/ directory. The settings.yml file defines which action is executed depending on the error:

• error_404_module and error_404_action: Action called when the URL entered by the user doesn't match any route or when an sfError404Exception occurs. The default value is default/error404.
• login_module and login_action: Action called when a nonauthenticated user tries to access a page defined as secure in security.yml (see Chapter 6 for details). The default value is default/login.
• secure_module and secure_action: Action called when a user doesn't have the credentials required for an action. The default value is default/secure.
• module_disabled_module and module_disabled_action: Action called when a user requests a module declared as disabled in module.yml. The default value is default/disabled.

Before deploying an application to production, you should customize these actions, because the default module templates include the symfony logo on the page. See Figure 19-1 for a screenshot of one of these pages, the error 404 page.

Figure 19-1 - Default 404 error page

You can override the default pages in two ways:

• You can create your own default module in the application's modules/ directory, override all the actions defined in the settings.yml file (index, error404, login, secure, disabled) and all the related templates (indexSuccess.php, error404Success.php, loginSuccess.php, secureSuccess.php, disabledSuccess.php).
• You can change the default module and action settings of the settings.yml file to use pages of your application.

Two other pages bear a symfony look and feel, and they also need to be customized before deployment to production. These pages are not in the default module, because they are called when symfony cannot run properly. Instead, you will find these default pages in the sfConfig::get('sf_symfony_lib_dir')/exception/data/ directory:

• error.html.php: Page called when an internal server error occurs in the production environment. In other environments (where debug is set to true), when an error occurs, symfony displays the full execution stack and an explicit error message (see Chapter 16 for details).
• unavailable.php: Page called when a user requests a page while the application is disabled (with the project:disable task). It is also called while the cache is being cleared (that is, between a call to the cache:clear task and the end of this task execution). On systems with a very large cache, the cache-clearing process can take several seconds. Symfony cannot execute a request with a partially cleared cache, so requests received before the end of the process are redirected to this page.

To customize these pages, simply create error/error.html.php and unavailable.php in your project or application's config/ directory. Symfony will use these templates instead of its own.

Optional Feature Activation

Some parameters of the settings.yml file control optional framework features that can be enabled or disabled. Deactivating unused features boosts performances a bit, so make sure to review the settings listed in Table 19-1 before deploying your application.

Table 19-1 - Optional Features Set Through settings.yml

Feature Configuration

Symfony uses some parameters of settings.yml to alter the behavior of built-in features such as form validation, cache, and third-party modules.

Output Escaping Settings

Output escaping settings control the way the variables are accessible in the template (see Chapter 7). The settings.yml file includes two settings for this feature:

• The escaping_strategy setting can take the value true, or false.
• The escaping_method setting can be set to ESC_RAW, ESC_SPECIALCHARS, ESC_ENTITIES, ESC_JS, or ESC_JS_NO_ENTITIES.

Routing Settings

The routing settings (see Chapter 9) are defined in factories.yml, under the routing key. Listing 19-1 show the default routing configuration.

Listing 19-1 - Routing Configuration Settings, in frontend/config/factories.yml

routing:
  class: sfPatternRouting
  param:
    load_configuration: true
    suffix:             .
    default_module:     default
    default_action:     index
    variable_prefixes:  [':']
    segment_separators: ['/', '.']
    variable_regex:     '[\w\d_]+'
    debug:              %SF_DEBUG%
    logging:            %SF_LOGGING_ENABLED%
    cache:
      class: sfFileCache
      param:
        automatic_cleaning_factor: 0
        cache_dir:                 %SF_CONFIG_CACHE_DIR%/routing
        lifetime:                  31556926
        prefix:                    %SF_APP_DIR%

• The suffix parameter sets the default suffix for generated URLs. The default value is a period (.), and it corresponds to no suffix. Set it to .html, for instance, to have all generated URLs look like static pages.
• When a routing rule doesn't define the module or the action parameter, values from the factories.yml are used instead:
  • default_module: Default module request parameter. Defaults to the default module.
  • default_action: Default action request parameter. Defaults to the index action.
• By default, route patterns identify named wildcards by a colon (:) prefix. But if you want to write your rules in a more PHP-friendly syntax, you can add the dollar ($) sign in the variable_prefixes array. That way, you can write a pattern like '/article/$year/$month/$day/$title' instead of '/article/:year/:month/:day/:title'.
• The pattern routing will identify named wildcards between separators. The default separators are the slash and the dot, but you can add more if you want in the segment_separators parameter. For instance, if you add the dash (-), you can write a pattern like '/article/:year-:month-:day/:title'.
• The pattern routing uses its own cache, in production mode, to speed up conversions between external URLs and internal URIs. By default, this cache uses the filesystem, but you can use any cache class, provided that you declare the class and its settings in the cache parameter. See Chapter 15 for the list of available cache storage classes. To deactivate the routing cache in production, set the debug parameter to true.

These are only the settings for the sfPatternRouting class. You can use another class for your application routing, either your own or one of symfony's routing factories (sfNoRouting and sfPathInfoRouting). With either of these two factories, all external URLs look like 'module/action?key1=param1'. No customization possible--but it's fast. The difference is that the first uses PHP's GET, and the second uses PATH_INFO. Use them mainly for backend interfaces.

There is one additional parameter related to routing, but this one is stored in settings.yml:

• no_script_name enables the front controller name in generated URLs. The no_script_name setting can be on only for a single application in a project, unless you store the front controllers in various directories and alter the default URL rewriting rules. It is usually on for the production environment of your main application and off for the others.

Form Validation Settings

Form validation settings control the way error messages output by the Validation helpers look (see Chapter 10). These errors are included in <div> tags, and they use the validation_error_ class setting as a class attribute and the validation_error_id_prefix setting to build up the id attribute. The default values are form_error and error_for_, so the attributes output by a call to the form_error() helper for an input named foobar will be class="form_error" id="error_for_foobar".

Two settings determine which characters precede and follow each error message: validation_error_prefix and validation_error_suffix. You can change them to customize all error messages at once.

Cache Settings

Cache settings are defined in cache.yml for the most part, except for two in settings.yml: cache enables the template cache mechanism, and etag enables ETag handling on the server side (see Chapter 15). You can also specify which storage to use for two all cache systems (the view cache, the routing cache, and the i18n cache) in factories.yml. Listing 19-2 show the default view cache factory configuration.

Listing 19-2 - View Cache Configuration Settings, in frontend/config/factories.yml

view_cache:
  class: sfFileCache
  param:
    automatic_cleaning_factor: 0
    cache_dir:                 %SF_TEMPLATE_CACHE_DIR%
    lifetime:                  86400
    prefix:                    %SF_APP_DIR%/template

The class can be any of sfFileCache, sfAPCCache, sfEAcceleratorCache, sfXCacheCache, sfMemcacheCache, and sfSQLiteCache. It can also be your own custom class, provided it extends sfCache and provides the same generic methods for setting, retrieving and deleting a key in the cache. The factory parameters depend on the class you choose, but there are constants:

• lifetime defines the number of seconds after which a cache part is removed
• prefix is a prefix added to every cache key (use the environment in the prefix to use different cache depending on the environment). Use the same prefix for two applications if you want their cache to be shared.

Then, for each particular factory, you have to define the location of the cache storage.

• for sfFileCache, the cache_dir parameter locates the absolute path to the cache directory
• sfAPCCache, sfEAcceleratorCache, and sfXCacheCache don't take any location parameter, since they use PHP native functions for communicating with APC, EAccelerator or the XCache cache systems
• for sfMemcacheCache, enter the hostname of the Memcached server in the host parameter, or an array of hosts in the servers parameter
• for sfSQLiteCache, the absolute path to the SQLite database file should be entered in the database parameter

For additional parameters, check the API documentation of each cache class.

The view is not the only component to be able to use a cache. Both the routing and the I18N factories offer a cache parameter in which you can set any cache factory, just like the view cache. For instance, Listing 19-1 shows of the routing uses the file cache for its speedup tactics by default, but you can change it to whatever you want.

Logging Settings

Two logging settings (see Chapter 16) are stored in settings.yml:

• error_reporting specifies which events are logged in the PHP logs. By default, it is set to E_PARSE | E_COMPILE_ERROR | E_ERROR | E_CORE_ERROR | E_USER_ERROR for the production environment (so the logged events are E_PARSE, E_COMPILE_ERROR, E_ERROR, E_CORE_ERROR, and E_USER_ERROR) and to E_ALL | E_STRICT for the development environment.
• The web_debug setting activates the web debug toolbar. Set it to true only in the development and test environments.

Paths to Assets

The settings.yml file also stores paths to assets. If you want to use another version of the asset than the one bundled with symfony, you can change these path settings:

• Files needed by the administration generator stored in admin_web_dir
• Files needed by the web debug toolbar stored in web_debug_web_dir

Default Helpers

Default helpers, loaded for every template, are declared in the standard_helpers setting (see Chapter 7). By default, these are the Partial and Cache helper groups. If you use a helper group in all templates of an application, adding its name to the standard_helpers setting saves you the hassle of declaring it with use_helper() on each template.

Activated Modules

Activated modules from plug-ins or from the symfony core are declared in the enabled_modules parameter. Even if a plug-in bundles a module, users can't request this module unless it is declared in enabled_modules. The default module, which provides the default symfony pages (congratulations, page not found, and so on), is the only enabled module by default.

Character Set

The character set of the responses is a general setting of the application, because it is used by many components of the framework (templates, output escaper, helpers, and so on). Defined in the charset setting, its default (and advised) value is utf-8.

all:
  creditcards:
    fake:             false    # app_creditcards_fake
    visa:             true     # app_creditcards_visa
    americanexpress:  true     # app_creditcards_americanexpress

Extending the Autoloading Feature

The autoloading feature, briefly explained in Chapter 2, exempts you from requiring classes in your code if they are located in specific directories. This means that you can just let the framework do the job for you, allowing it to load only the necessary classes at the appropriate time, and only when needed.

The autoload.yml file lists the paths in which autoloaded classes are stored. The first time this configuration file is processed, symfony parses all the directories referenced in the file. Each time a file ending with .php is found in one of these directories, the file path and the class names found in this file are added to an internal list of autoloading classes. This list is saved in the cache, in a file called config/config_autoload.yml.php. Then, at runtime, when a class is used, symfony looks in this list for the class path and includes the .php file automatically.

Autoloading works for all .php files containing classes and/or interfaces.

By default, classes stored in the following directories in your projects benefit from the autoloading automatically:

• myproject/lib/
• myproject/lib/model
• myproject/apps/frontend/lib/
• myproject/apps/frontend/modules/mymodule/lib

There is no autoload.yml file in the default application configuration directory. If you want to modify the framework settings--for instance, to autoload classes stored somewhere else in your file structure--create an empty autoload.yml file and override the settings of sfConfig::get('sf_symfony_lib_dir')/config/config/autoload.yml or add your own.

The autoload.yml file must start with an autoload: key and list the locations where symfony should look for classes. Each location requires a label; this gives you the ability to override symfony's entries. For each location, provide a name (it will appear as a comment in config_autoload.yml.php) and an absolute path. Then define if the search must be recursive, which directs symfony to look in all the subdirectories for .php files, and exclude the subdirectories you want. Listing 19-3 shows the locations used by default and the file syntax.

Listing 19-3 - Default Autoloading Configuration, in sfConfig::get('sf_symfony_lib_dir')/config/config/autoload.yml

autoload:
  # plugins
  plugins_lib:
    name:           plugins lib
    path:           %SF_PLUGINS_DIR%/*/lib
    recursive:      true

  plugins_module_lib:
    name:           plugins module lib
    path:           %SF_PLUGINS_DIR%/*/modules/*/lib
    prefix:         2
    recursive:      true

  # project
  project:
    name:           project
    path:           %SF_LIB_DIR%
    recursive:      true
    exclude:        [model, symfony]

  project_model:
    name:           project model
    path:           %SF_LIB_DIR%/model
    recursive:      true

  # application
  application:
    name:           application
    path:           %SF_APP_LIB_DIR%
    recursive:      true

  modules:
    name:           module
    path:           %SF_APP_DIR%/modules/*/lib
    prefix:         1
    recursive:      true

A rule path can contain wildcards and use the file path parameters defined in the configuration classes (see the next section). If you use these parameters in the configuration file, they must appear in uppercase and begin and end with %.

Editing your own autoload.yml will add new locations to symfony's autoloading, but you may want to extend this mechanism and add your own autoloading handler to symfony's handler. As symfony uses the standard spl_autoload_register() function to manage class autoloading, you can register more callbacks in the application configuration class:

class frontendConfiguration extends sfApplicationConfiguration
{
  public function initialize()
  {
    parent::initialize(); // load symfony autoloading first
 
    // insert your own autoloading callables here
    spl_autoload_register(array('myToolkit', 'autoload'));
  }
}

When the PHP autoloading system encounters a new class, it will first try the symfony autoloading method (and use the locations defined in autoload.yml). If it doesn't find a class definition, all the other callables registered with spl_autoload_register() will be called, until the class is found. So you can add as many autoloading mechanisms as you want--for instance, to provide a bridge to other framework components (see Chapter 17).

Custom File Structure

Each time the framework uses a path to look for something (from core classes to templates, plug-ins, configurations, and so on), it uses a path variable instead of an actual path. By changing these variables, you can completely alter the directory structure of a symfony project, and adapt to the file organization requirements of any client.

The Basic File Structure

The path variables are defined in the sfProjectConfiguration and sfApplicationConfiguration classes and stored in the sfConfig object. Listing 19-4 shows a listing of the path variables and the directory they reference.

Listing 19-4 - Default File Structure Variables, defined in sfProjectConfiguration and sfApplicationConfiguration

sf_root_dir           # myproject/
sf_apps_dir           #   apps/
sf_app_dir            #     frontend/
sf_app_config_dir     #       config/
sf_app_i18n_dir       #       i18n/
sf_app_lib_dir        #       lib/
sf_app_module_dir     #       modules/
sf_app_template_dir   #       templates/
sf_cache_dir          #   cache/
sf_app_base_cache_dir #     frontend/
sf_app_cache_dir      #       prod/
sf_template_cache_dir #         templates/
sf_i18n_cache_dir     #         i18n/
sf_config_cache_dir   #         config/
sf_test_cache_dir     #         test/
sf_module_cache_dir   #         modules/
sf_config_dir         #   config/
sf_data_dir           #   data/
sf_lib_dir            #   lib/
sf_log_dir            #   log/
sf_test_dir           #   test/
sf_plugins_dir        #   plugins/
sf_web_dir            #   web/
sf_upload_dir         #     uploads/

Every path to a key directory is determined by a parameter ending with _dir. Always use the path variables instead of real (relative or absolute) file paths, so that you will be able to change them later, if necessary. For instance, when you want to move a file to the uploads/ directory in an application, you should use sfConfig::get('sf_upload_dir') for the path instead of sfConfig::get('sf_root_dir').'/web/uploads/'.

Customizing the File Structure

You will probably need to modify the default project file structure if you develop an application for a client who already has a defined directory structure and who is not willing to change it to comply with the symfony logic. By overriding the sf_XXX_dir variables with sfConfig, you can make symfony work for a totally different directory structure than the default structure. The best place to do this is in the application ProjectConfiguration class for project directories, or XXXConfiguration class for applications directories.

For instance, if you want all applications to share a common directory for the template layouts, add this line to the setup() method of the ProjectConfiguration class to override the sf_app_template_dir settings:

sfConfig::set('sf_app_template_dir', sfConfig::get('sf_root_dir').DIRECTORY_SEPARATOR.'templates');

Modifying the Project Web Root

All the paths built in the configuration classes rely on the project root directory, which is determined by the ProjectConfiguration file included in the front controller. Usually, the root directory is one level above the web/ directory, but you can use a different structure. Suppose that your main directory structure is made of two directories, one public and one private, as shown in Listing 19-5. This typically happens when hosting a project on a shared host.

Listing 19-5 - Example of Custom Directory Structure for a Shared Host

symfony/    # Private area
  apps/
  config/
  ...
www/        # Public area
  images/
  css/
  js/
  index.php

In this case, the root directory is the symfony/ directory. So the index.php front controller simply needs to include the config/ProjectConfiguration.class.php file as follows for the application to work:

require_once(dirname(__FILE__).'/../symfony/config/ProjectConfiguration.class.php');

In addition, use the setWebDir() method to change the public area from the usual web/ to www/, as follows:

class ProjectConfiguration extends sfProjectConfiguration
{
  public function setup()
  {
    // ...
 
    $this->setWebDir($this->getRootDir().'/../www');
  }
}

Understanding Configuration Handlers

Each configuration file has a handler. The job of configuration handlers is to manage the configuration cascade, and to do the translation between the configuration files and the optimized PHP code executable at runtime.

Default Configuration Handlers

The default handler configuration is stored in sfConfig::get('sf_symfony_lib_dir')/config/config/config_handlers.yml. This file links the handlers to the configuration files according to a file path. Listing 19-6 shows an extract of this file.

Listing 19-6 - Extract of sfConfig::get('sf_symfony_lib_dir')/config/config/config_handlers.yml

config/settings.yml:
  class:    sfDefineEnvironmentConfigHandler
  param:
    prefix: sf_

config/app.yml:
  class:    sfDefineEnvironmentConfigHandler
  param:
    prefix: app_

config/filters.yml:
  class:    sfFilterConfigHandler

modules/*/config/module.yml:
  class:    sfDefineEnvironmentConfigHandler
  param:
    prefix: mod_
    module: yes

For each configuration file (config_handlers.yml identifies each file by a file path with wildcards), the handler class is specified under the class key.

The settings of configuration files handled by sfDefineEnvironmentConfigHandler can be made available directly in the code via the sfConfig class, and the param key contains a prefix value.

You can add or modify the handlers used to process each configuration file--for instance, to use INI or XML files instead of YAML files.

If you ever need to modify the way the configuration is parsed, create an empty config_handlers.yml file in your application's config/ folder and override the class lines with the classes you wrote.

Adding Your Own Handler

Using a handler to deal with a configuration file provides two important benefits:

• The configuration file is transformed into executable PHP code, and this code is stored in the cache. This means that the configuration is parsed only once in production, and the performance is optimal.
• The configuration file can be defined at different levels (project and application) and the final parameter values will result from a cascade. So you can define parameters at a project level and override them on a per-application basis.

If you feel like writing your own configuration handler, follow the example of the structure used by the framework in the sfConfig::get('sf_symfony_lib_dir')/config/ directory.

Let's suppose that your application contains a myMapAPI class, which provides an interface to a third-party web service delivering maps. This class needs to be initialized with a URL and a user name, as shown in Listing 19-7.

Listing 19-7 - Example of Initialization of the myMapAPI Class

$mapApi = new myMapAPI();
$mapApi->setUrl($url);
$mapApi->setUser($user);

You may want to store these two parameters in a custom configuration file called map.yml, located in the application config/ directory. This configuration file might contain the following:

api:
  url:  map.api.example.com
  user: foobar

In order to transform these settings into code equivalent to Listing 19-7, you must build a configuration handler. Each configuration handler must extend sfConfigHandler and provide an execute() method, which expects an array of file paths to configuration files as a parameter, and must return data to be written in a cache file. Handlers for YAML files should extend the sfYamlConfigHandler class, which provides additional facilities for YAML parsing. For the map.yml file, a typical configuration handler could be written as shown in Listing 19-8.

Listing 19-8 - A Custom Configuration Handler, in frontend/lib/myMapConfigHandler.class.php

<?php
 
class myMapConfigHandler extends sfYamlConfigHandler
{
  public function execute($configFiles)
  {
    // Parse the yaml
    $config = $this->parseYamls($configFiles);
 
    $data  = "<?php\n";
    $data .= "\$mapApi = new myMapAPI();\n";
 
    if (isset($config['api']['url'])
    {
      $data .= sprintf("\$mapApi->setUrl('%s');\n", $config['api']['url']);
    }
 
    if (isset($config['api']['user'])
    {
      $data .= sprintf("\$mapApi->setUser('%s');\n", $config['api']['user']);
    }
 
    return $data;
  }
}

The $configFiles array that symfony passes to the execute() method will contain a path to all the map.yml files found in the config/ folders. The parseYamls() method will handle the configuration cascade.

In order to associate this new handler with the map.yml file, you must create a config_handlers.yml configuration file with the following content:

config/map.yml:
  class: myMapConfigHandler

As with many other symfony configuration files, you can also register a configuration handler directly in your PHP code:

sfContext::getInstance()->getConfigCache()->registerConfigHandler('config/map.yml', 'myMapConfigHandler', array());

When you need the code based on the map.yml file and generated by the myMapConfigHandler handler in your application, call the following line:

include sfContext::getInstance()->getConfigCache()->checkConfig('config/map.yml');

When calling the checkConfig() method, symfony looks for existing map.yml files in the configuration directories and processes them with the handler specified in the config_handlers.yml file, if a map.yml.php does not already exist in the cache or if the map.yml file is more recent than the cache.

config/map.yml:
  class: sfDefineEnvironmentConfigHandler
  param:
    prefix: map_

Summary

The configuration files can heavily modify the way the framework works. Because symfony relies on configuration even for its core features and file loading, it can adapt to many more environments than just the standard dedicated host. This great configurability is one of the main strengths of symfony. Even if it sometimes frightens newcomers, who see in configuration files a lot of conventions to learn, it allows symfony applications to be compatible with a very large number of platforms and environments. Once you become a master of symfony's configuration, no server will ever refuse to run your applications!