The ExpressionLanguage component has been around for quite some time, and its usefulness is no longer to be proven. Many popular projects like OroCRM, Sylius, or Symfony itself use it.

This component can be seen as a PHP sandbox and is mainly used to set up an application by allowing for advanced configuration. It can also be used as an engine to implement business rules. Indeed, by using the component in this way, it is possible to let end users write configurations in an understandable, secure, and dynamic way.

This last aspect is really interesting and is what I want to explain.

During this talk, we will re-discover the ExpressionLanguage component by getting an overview of the conventional way it is used. Then, through a concrete example, we will see the real potential of this component. In an e-commerce context, we will create a system that allows administrators to write business rules. These rules will dynamically apply promotions.

At the end of the talk, we will know how to use the ExpressionLanguage component to let end users build their own business rules.