=== Smoother UI

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:page-partial:

Often an action, when invoked, will return the target (in other words, will "return this").
The xref:refguide:applib:index/annotation/ActionLayout.adoc#redirectPolicy[redirectPolicy()] element is used to control how the object is re-rendered.

There are three options:

* if set to `ONLY_IF_DIFFERS`, then the existing web page will not be re-rendered, rather it will be updated in-place (using Ajax).
+
This makes for a smoother UI.
+
[NOTE]
====
Any properties with xref:refguide:applib:index/annotation/PropertyLayout.adoc#repainting[@PropertyLayout#repainting] set to `NO_REPAINT` are then _not_ updated.
====

* if set to `EVEN_IF_SAME`, then a redirect occurs and a new web page is rendered.

* if set to `AS_CONFIGURED`, then the default behaviour is as specified by the `isis.viewer.wicket.redirectEvenIfSameObject` xref:vw:ROOT:setup-and-configuration.adoc[configuration property]).

One use case for choosing `EVEN_IF_SAME` is if the action "returning this" is intended in some way to require that the object use a different layout, as per multiple layout support, as specified using the xref:refguide:applib-methods:ui-hints.adoc#layout[layout()] method.

For example:

[source,java]
----
import lombok.Getter;
import lombok.Setter;

public class Customer {

    @Getter @Setter
    @PropertyLayout(hidden=ALWAYS)
    private String layout;

    public String layout() {                // <.>
        return layout;
    }

    @ActionLayout(
        redirect=EVEN_IF_SAME               // <.>
    )
    public Customer switchToEditMode() {
        setLayout("edit");
        return this;
    }
}
----

<.> specifies the alternate layout to use, eg `Customer-edit.layout.xml`.

<.> even though this action returns the same target object, still re-render the page.

If `switchToEditMode()` action is invoked, then the UI will attempt to render the customer using a `Customer.layout.edit.xml` layout file (instead of the default `Customer.layout.xml`).

