Dynamic Transitions in Spring WebFlow

Question

Does anybody know if it's possible to define dynamic transitions in a Spring Web Flow definition?

Example 1 - using a properties file:

<action-state id="createSubscription" >
    <evaluate expression="myvar" />
    <transition on="$[test.result.valid]" to="subscribeUser-successResponse" />
    <transition                               to="subscribeUser-exceptionResponse" />
</action-state>

Example 2 - using the value of the variable itself:

<action-state id="createSubscription" >
    <evaluate expression="myvar" />
    <transition to="$[myvar]" />
</action-state>

It's not mandatory, but could help to design more generic flows.

Thanks in advance to everyone.

Answer 1

You can do definitely do for transition "to". Suppose flow xml has some action and view state as:

    <action-state id="createSubscription">
        <evaluate expression="myAction.prepareNextState(flowScope.formBean)"/>
        <transition to="${flowScope.formBean.displayNextState}">
    </action-state>

    <view-state id="someView" view="someView" model="formBean">
        ...
    </view-state>

and myAction class with prepareNextState method is as:

    public class MyAction implements Serializable{
        ....
        public void prepareNextState(FormBean formBean){
            //displayNextState is a String field in FormBean                
            formBean.setDisplayNextState("someView");
        }
        ....
    }

This way we can define generic transitions for transition "to".