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#JLMSerializerExpressionBundle

This bundle adds makes it simple to integrate the JLMSerializerExpression library into your Symfony application. The library adds an @excludeIf annotation with expression language support to JMSSerializerBundle so that individual fields can be hidden based on expressions at runtime.

This bundle registers the necessary services in the DI container including a pre-configured ExclusionStrategy object which can be added directly to any SerializationContext.

Installation

This bundle can be installed via Composer by adding the following to your composer.json file:

"require": {
    # ..
    "jlm/serializer-expression-bundle": "dev-master"
    # ..
}

Then add the bundle to your Kernel in AppKernel.php (if using Symfony Standard):

public function registerBundles()
    {
        $bundles = array(
            /* ... */
            new JLM\SerializerExpressionBundle\JLMSerializerExpressionBundle(),
        );

        return $bundles;
    }

Configuration

This bundle currently has no configuration exposed. It will work out of the box.

Services

The bundle will provide the following pre-configured services. Please see the SerializerExpression library for more detail on what these individual services are for.

jlm_serializer_expression.expression_based_exclusion_strategy

This is the bundled, pre-configured exclusion strategy that will run expressions provided by @excludeIf annotations to determine at runtime whether or not to include a particular object property. This is likely the only service you will need.

jlm_serializer_expression.metadata.metadata_factory

This service is an instance of Metadata\MetadataFactory from Johannes Schmitt's Metadata library. This factory comes preconfigured with an Annotation driver to read the excludeIf annotations and a file based cache using your Symfony application's kernel cache directory. If you choose to instantiate a separate instance of JLM\SerializerExpression\Exclusion\ExpressionBasedExclusionStrategy this is the metadata factory you should pass along to it unless you have a good reason for using another.

jlm_serializer_expression.expression_language

This is the bundled expression language (instance of Symfony\Component\ExpressionLanguage\ExpressionLanguage which provides access to all services, containers, and includes a secure method for directly passing security expressions. This is the language used by the @excludeIf annotation and is the language that the pre-configured exclusion strategy is passed. For more information on the expression language, see the relevant Symfony documentation.

The bundled version of the ExpressionLanguage provides the following methods:

• param - Accepts the name of a parameter and returns its value, eg: @excludeIf("param('myParam') == true")
• service - Accepts the ID of a service and returns it, eg: @excludeIf("service('mySerivce').foo()")
• secure - Accepts a string which is itself an expression, passed directly to the security context, eg: `@excludeIf("secure(""has_role('ROLE_ADMIN')"")") (Note the double quotes which is how we embed an expression within an expression)

jlm_serializer_expression.fos_rest_view_handler

This service provides integration with FOSRestBundle, detailed below.

Annotating Your Classes

<?php

use JLM\SerializerExpression\Annotation\ExcludeIf;

class User
{
    
    public $firstName = 'Jason';

    public $lastName = 'McClellan';
   /**
     * @ExcludeIf("secure(""has_role('ROLE_ADMIN')"")")
     */
    public $phone = '555-555-5555';
    /**
     * @ExcludeIf("secure(""has_role('ROLE_ADMIN')"")")
     */
    public $address ='New York, NY';

    public $occupation = 'Software';
}

The above annotations would ensure that the $phone and $address fields are only serialized for users with the role ROLE_ADMIN. Notice we are using the secure function which is provided by this bundle's ExpressionLanguage implementation.

Using the Exclusion Strategy

When serializing the object using an instance of JMS\Serializer\Serializer, you must add our exclusion strategy to the SerializationContext instance and pass it to the serialize() method along with the object instance and desired format. Here is a rather verbose example:

use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Response;
use JMS\Serializer\SerializerBuilder;
use JMS\Serializer\SerializationContext;

class UserController extends Controller
{
    public function getUsers()
    {
        $users = ...
        $serializationContext = SerializationContext::create();
        $exclusionStrategy = $this->get('jlm_serializer_expression.expression_based_exclusion_strategy');
        $serializationContext->addExclusionStrategy($exclusionStrategy);
        // $serializer = $this->get('jms_serializer') // if using JMSSerializerBundle
        $serializer = SerializerBuilder::create()->build();

        $serializedContent = $serializer->serialize($data, 'json', $serializationContext);
        
        $response = new Response($serializedContent);
        $response->headers->set('Content-Type', 'application/json');
        
        return $response;
    }
}

FOSRestBundle Integration

If you are using FOSRestBundle in order to more easily create format-agnostic controllers (and you should!) then the serialization process is far easier. The only thing you have to do is change a bit of configuration for FOSRestBundle so that it uses the ViewHandler provided by this bundle, which will automatically add the new ExpressionBasedExclusionStrategy to the built-in SerializationContext used by FOSRestBundle.

fos_rest:
  service:
    view_handler: jlm_serializer_expression.fos_rest_view_handler

That's it! Your annotated classes will automatically be serialized properly, respecting the @excludeIf annotations.