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Exposing SiteAccess-aware configuration for your bundle

Description

Symfony Config component makes it possible to define semantic configuration, exposed to the end developer. This configuration is validated by rules you define, e.g. validating type (string, array, integer, boolean, etc.). Usually, once validated and processed, this semantic configuration is then mapped to internal key/value parameters stored in the ServiceContainer.

eZ Platform uses this for its core configuration, but adds another configuration level, the siteaccess. For each defined siteaccess, we need to be able to use the same configuration tree in order to define siteaccess-specific config. These settings then need to be mapped to siteaccess-aware internal parameters that you can retrieve via the ConfigResolver. For this, internal keys need to follow the format <namespace>.<scope>.<parameter_name>namespace being specific to your app/bundle, scope being the siteaccess, siteaccess group, default or globalparameter_name being the actual setting identifier.

For more information on ConfigResolver, namespaces and scopes, see eZ Platform configuration basics.

The goal of this feature is to make it easy to implement a siteaccess-aware semantic configuration and its mapping to internal config for any eZ bundle developer.

Solution

Semantic configuration parsing

An abstract Configuration class has been added, simplifying the way to add a siteaccess settings tree like the following:

# ezplatform.yml or config.yml
acme_demo:
    system:
        my_siteaccess:
            hello: "world"
            foo_setting:
                an_integer: 456
                enabled: true

        my_siteaccess_group:
            hello: "universe"
            foo_setting:
                foo: "bar"
                some: "thing"
                an_integer: 123
                enabled: false

Class FQN is eZ\Bundle\EzPublishCoreBundle\DependencyInjection\Configuration\SiteAccessAware\Configuration. All you have to do is to extend it and use $this->generateScopeBaseNode():

namespace Acme\DemoBundle\DependencyInjection;

use eZ\Bundle\EzPublishCoreBundle\DependencyInjection\Configuration\SiteAccessAware\Configuration as SiteAccessConfiguration;
use Symfony\Component\Config\Definition\Builder\NodeBuilder;
use Symfony\Component\Config\Definition\Builder\TreeBuilder;

class Configuration extends SiteAccessConfiguration
{
    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root( 'acme_demo' );

        // $systemNode will then be the root of siteaccess aware settings.
        $systemNode = $this->generateScopeBaseNode( $rootNode );
        $systemNode
            ->scalarNode( 'hello' )->isRequired()->end()
            ->arrayNode( 'foo_setting' )
                ->children()
                    ->scalarNode( "foo" )->end()
                    ->scalarNode( "some" )->end()
                    ->integerNode( "an_integer" )->end()
                    ->booleanNode( "enabled" )->end()
                ->end()
            ->end();

        return $treeBuilder;
    }
}

Note

Default name for the siteaccess root node is system, but you can customize it. For this, just pass the name you want to use as a second argument of $this->generateScopeBaseNode().

Mapping to internal settings

Semantic configuration must always be mapped to internal key/value settings within the ServiceContainer. This is usually done in the DIC extension.

For siteaccess-aware settings, new ConfigurationProcessor and Contextualizer classes have been introduced to ease the process.

namespace Acme\DemoBundle\DependencyInjection;

use eZ\Bundle\EzPublishCoreBundle\DependencyInjection\Configuration\SiteAccessAware\ConfigurationProcessor;
use eZ\Bundle\EzPublishCoreBundle\DependencyInjection\Configuration\SiteAccessAware\ContextualizerInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\Config\FileLocator;
use Symfony\Component\HttpKernel\DependencyInjection\Extension;
use Symfony\Component\DependencyInjection\Loader;

/**
 * This is the class that loads and manages your bundle configuration
 *
 * To learn more see {@link http://symfony.com/doc/current/cookbook/bundles/extension.html}
 */
class AcmeDemoExtension extends Extension
{
    public function load( array $configs, ContainerBuilder $container )
    {
        $configuration = $this->getConfiguration( $configs, $container );
        $config = $this->processConfiguration( $configuration, $configs );

        $loader = new Loader\YamlFileLoader( $container, new FileLocator( __DIR__.'/../Resources/config' ) );
        $loader->load( 'default_settings.yml' );

        // "acme_demo" will be the namespace as used in ConfigResolver format.
        $processor = new ConfigurationProcessor( $container, 'acme_demo' );
        $processor->mapConfig(
            $config,
            // Any kind of callable can be used here.
            // It will be called for each declared scope/SiteAccess.
            function ( $scopeSettings, $currentScope, ContextualizerInterface $contextualizer )
            {
                // Will map "hello" setting to "acme_demo.<$currentScope>.hello" container parameter
                // It will then be possible to retrieve this parameter through ConfigResolver in the application code:
                // $helloSetting = $configResolver->getParameter( 'hello', 'acme_demo' );
                $contextualizer->setContextualParameter( 'hello', $currentScope, $scopeSettings['hello'] );
            }
        );

        // Now map "foo_setting" and ensure keys defined for "my_siteaccess" overrides the one for "my_siteaccess_group"
        // It is done outside the closure as it is needed only once.
        $processor->mapConfigArray( 'foo_setting', $config );
    }
}

Tip

You can map simple settings by calling $processor->mapSetting(), without having to call $processor->mapConfig() with a callable.

$processor = new ConfigurationProcessor( $container, 'acme_demo' );
$processor->mapSetting( 'hello', $config );

Important

Always ensure you have defined and loaded default settings.

# @AcmeDemoBundle/Resources/config/default_settings.yml
parameters:
    acme_demo.default.hello: world
    acme_demo.default.foo_setting:
        foo: ~
        some: ~
        planets: [Earth]
        an_integer: 0
        enabled: false
        j_adore: les_sushis

Merging hash values between scopes

When you define a hash as semantic config, you sometimes don't want the siteaccess settings to replace the default or group values, but enrich them by appending new entries. This is made possible by using $processor->mapConfigArray(), which needs to be called outside the closure (before or after), in order to be called only once.

Consider the following default config:

# default_settings.yml
parameters:
    acme_demo.default.foo_setting:
        foo: ~
        some: ~
        planets: [Earth]
        an_integer: 0
        enabled: false
        j_adore: les_sushis

And then this semantic config:

# ezplatform.yml or config.yml
acme_demo:
    system:
        sa_group:
            foo_setting:
                foo: bar
                some: thing
                an_integer: 123

        # Assuming "sa1" is part of "sa_group"
        sa1:
            foo_setting:
                an_integer: 456
                enabled: true
                j_adore: le_saucisson

What we want here is that keys defined for foo_setting are merged between default/group/siteaccess:

# Expected result
parameters:
    acme_demo.sa1.foo_setting:
        foo: bar
        some: thing
        planets: [Earth]
        an_integer: 456
        enabled: true
        j_adore: le_saucisson
Merge from second level

In the example above, entries were merged in respect to the scope order of precedence. However, if we define the planets key forsa1, it will completely override the default value since the merge process is done at only 1 level.

You can add another level by passing ContextualizerInterface::MERGE_FROM_SECOND_LEVEL as an option (3rd argument) to$contextualizer->mapConfigArray().

# default_settings.yml
parameters:
    acme_demo.default.foo_setting:
        foo: ~
        some: ~
        planets: [Earth]
        an_integer: 0
        enabled: false
        j_adore: [les_sushis]
# Semantic config (ezplatform.yml / config.yml)
acme_demo:
    system:
        sa_group:
            foo_setting:
                foo: bar
                some: thing
                planets: [Mars, Venus]
                an_integer: 123

        # Assuming "sa1" is part of "sa_group"
        sa1:
            foo_setting:
                an_integer: 456
                enabled: true
                j_adore: [le_saucisson, la_truite_a_la_vapeur]

Result of using ContextualizerInterface::MERGE_FROM_SECOND_LEVEL option:

parameters:
    acme_demo.sa1.foo_setting:
        foo: bar
        some: thing
        planets: [Earth, Mars, Venus]
        an_integer: 456
        enabled: true
        j_adore: [les_suhis, le_saucisson, la_truite_a_la_vapeur]

There is also another option, ContextualizerInterface::UNIQUE, to be used when you want to ensure your array setting has unique values. It will only work on normal arrays though, not hashes.

Limitations

A few limitation exist with this scope hash merge:

  • Semantic setting name and internal name will be the same (like foo_setting in the examples above).
  • Applicable to first level semantic parameter only (i.e. settings right under the siteaccess name).
  • Merge is not recursive. Only second level merge is possible by using ContextualizerInterface::MERGE_FROM_SECOND_LEVEL option.

Dedicated mapper object

Instead of passing a callable to $processor->mapConfig(), an instance of eZ\Bundle\EzPublishCoreBundle\DependencyInjection\Configuration\SiteAccessAware\ConfigurationMapperInterface can be passed.

This can be useful if you have a lot of configuration to map and don't want to pollute your DIC extension class (better for maintenance).

Merging hash values between scopes

As specified above, $contextualizer->mapConfigArray() is not to be used within the scope loop, like for simple values. When using a closure/callable, you usually call it before or after $processor->mapConfig(). For mapper objects, a dedicated interface can be used: HookableConfigurationMapperInterface, which defines 2 methods: preMap() and postMap().

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