So, it would be nice to add the container and the request as context values:

```xml
<call method="setContextValue">
    <argument>container</argument>
    <argument type="service" id="service_container"/>
</call>
<call method="setContextValue">
    <argument>request</argument>
    <argument type="service" id="request" on-invalid="null" strict="false" />
</call>
```

Though I don't know if the request trick is available in symfony 2.1