Flash

Specially when working with forms it is useful to pass certain informations (e.g. error- or success messages) to the next request. To do this in a stateless environment, mangoo I/O uses the Flash class. This is basically the same mechanism as a session, but all informations are stored in a special flash cookie which is disposed once the request is finished.

Just pass the Flash class to your controller as follows:

package controllers;

import io.mangoo.routing.Response;
import io.mangoo.routing.bindings.Flash;

public class FlashController {
    public Response flash(Flash flash) {
        flash.success("this is a success");
        flash.warning("this is a warning");
        flash.error("this is an error");
        flash.add("foo", "bar");

       return Response.withRedirect("/");
    }
}

The Flash class has three convenient methods for commonly used scenarios: success, warning and error. This methods will automatically create a key “success”, “warning” or “error” in the flash class. Besides that, you can pass custom keys and values to the flash class.

Flash in templates

To access the flash values, simply call the appropriate key in your template.

${flash.success}
${flash.warning}
${flash.error}
${flash.foo}

The Flash class is automatically available in the template so you don’t have to pass the class to the template via a controller.