A filter in Crafter is a Groovy-based controller that allows you to intercept inbound requests for content and API responses and dynamically apply rules, modify the request or transform the response. A Crafter Filter has the same interface and mechanics as a Java J2EE Servlet Filter. Some examples of filter use are:
Apply security rules: Check for SAML2, Site Minder, or other security tokens before allowing the request to proceed.
Active Record: Example: before serving the requested resource, look up and load the user’s profile into the request so it is available to all components of the system.
Apply compression: Gzip all of the data returned by the requested resource (page, API, etc)
In this article, we’ll learn the specific mechanics of creating and configuring a filter in Crafter CMS.