title: Unknown database type json requested, Doctrine\DBAL\Platforms\PostgreSqlPlatform may not support it
body: <blockquote>
    <p>Developing using Symfony 2.7</p>
  </blockquote>
  
  <p>I have <strong><em>entity</em></strong> which contain attribute </p>
  
  <pre><code>/**
   * @var array
   * @ORM\Column(name="new_entry_name", type="json_array", nullable=true)
   */
  protected $newEntryName;
  </code></pre>
  
  <p>but when i update my <strong><em>schema</em></strong> using </p>
  
  <pre><code>php app/console doctrine:schema:update --force
  </code></pre>
  
  <p>it shows me <strong><em>error</em></strong></p>
  
  <pre><code>$ php app/console doctrine:schema:update --force
  [Doctrine\DBAL\DBALException]                                                                         
  
  Unknown database type json requested, Doctrine\DBAL\Platforms\PostgreSqlPlatform may not support it.
  </code></pre>
  
  <p>In <strong><em>config.yml</em></strong> file i have added this type.</p>
  
  <p><code>doctrine:
      dbal:
          driver:   "pdo_pgsql"
          host:     "%database_host%"
          port:     "%database_port%"
          dbname:   "%database_name%"
          user:     "%database_user%"
          password: "%database_password%"
          charset:  UTF8
          mapping_types:
              enum: string
              set: string
              varbinary: string
              tinyblob: text
          types:
              json: Sonata\Doctrine\Types\JsonType</code></p>
  
  <p>what should i do to avoid this error .Thanks                                                      </p>