added viewState method to allow stateful views to update their view scope state on view state exit

spring-webflow/src/main/java/org/springframework/webflow/engine/RequestControlContext.java

@@ -60,13 +60,19 @@ public interface RequestControlContext extends RequestContext {
 	public FlowExecutionKey assignFlowExecutionKey();
 
 	/**
-	 * Called when a view is about to be rendered in the current view state.
+	 * Sets the current view.
+	 * @param view the current view, or null to mark the current view as <code>null</code>
+	 */
+	public void setCurrentView(View view);
+
+	/**
+	 * Called when the current view is about to be rendered in the current view state.
 	 * @param view the view to be rendered
 	 */
 	public void viewRendering(View view);
 
 	/**
-	 * Called when a view has completed rendering in the current view state.
+	 * Called when the current view has completed rendering in the current view state.
 	 * @param view the view that rendered
 	 */
 	public void viewRendered(View view);

spring-webflow/src/main/java/org/springframework/webflow/engine/ViewState.java

@@ -182,6 +182,7 @@ public class ViewState extends TransitionableState {
 				}
 			} else {
 				View view = viewFactory.getView(context);
+				context.setCurrentView(view);
 				render(context, view);
 			}
 		}
@@ -190,6 +191,7 @@ public class ViewState extends TransitionableState {
 	public void resume(RequestControlContext context) {
 		restoreVariables(context);
 		View view = viewFactory.getView(context);
+		context.setCurrentView(view);
 		if (view.userEventQueued()) {
 			boolean stateExited = handleEvent(view, context);
 			if (!stateExited) {
@@ -244,6 +246,7 @@ public class ViewState extends TransitionableState {
 		super.exit(context);
 		updateHistory(context);
 		destroyVariables(context);
+		context.setCurrentView(null);
 	}
 
 	// internal helpers
@@ -306,6 +309,10 @@ public class ViewState extends TransitionableState {
 		TransitionDefinition transition = context.getCurrentTransition();
 		History history = (History) transition.getAttributes().get("history");
 		if (history == null || history == History.PRESERVE) {
+			View currentView = context.getCurrentView();
+			if (currentView != null) {
+				currentView.saveState();
+			}
 			context.updateCurrentFlowExecutionSnapshot();
 		} else if (history == History.DISCARD) {
 			context.removeCurrentFlowExecutionSnapshot();

spring-webflow/src/main/java/org/springframework/webflow/engine/impl/RequestControlContextImpl.java

@@ -81,6 +81,11 @@ class RequestControlContextImpl implements RequestControlContext {
 	 */
 	private Transition currentTransition;
 
+	/**
+	 * The current view associated with this request context; initially null.
+	 */
+	private View currentView;
+
 	/**
 	 * Create a new request context.
 	 * @param flowExecution the owning flow execution
@@ -157,6 +162,10 @@ class RequestControlContextImpl implements RequestControlContext {
 		return currentTransition;
 	}
 
+	public View getCurrentView() {
+		return currentView;
+	}
+
 	public MutableAttributeMap getAttributes() {
 		return attributes;
 	}
@@ -184,6 +193,10 @@ class RequestControlContextImpl implements RequestControlContext {
 		return flowExecution.assignKey();
 	}
 
+	public void setCurrentView(View currentView) {
+		this.currentView = currentView;
+	}
+
 	public void viewRendering(View view) {
 		flowExecution.viewRendering(view, this);
 	}

spring-webflow/src/main/java/org/springframework/webflow/engine/support/ActionExecutingViewFactory.java

@@ -79,6 +79,10 @@ public class ActionExecutingViewFactory implements ViewFactory {
 			userEventProcessed = true;
 		}
 
+		public Object getUserEventState() {
+			return null;
+		}
+
 		public boolean hasFlowEvent() {
 			return userEventProcessed && getEventId() != null;
 		}
@@ -90,8 +94,8 @@ public class ActionExecutingViewFactory implements ViewFactory {
 			return new Event(this, eventId);
 		}
 
-		public Object getUserEventState() {
-			return null;
+		public void saveState() {
+
 		}
 
 		private String getEventId() {

spring-webflow/src/main/java/org/springframework/webflow/execution/RequestContext.java

@@ -185,6 +185,14 @@ public interface RequestContext {
 	 */
 	public TransitionDefinition getCurrentTransition();
 
+	/**
+	 * Returns the current view in use; if not null, the view returned is about to be rendered, is rendering, is
+	 * processing a user event, or has finished user event processing and the current ViewState is exiting due to a
+	 * state transition. Returns <code>null</code> if the flow is not in a view state.
+	 * @return the current view, or <code>null</code> if the flow is not in a view state
+	 */
+	public View getCurrentView();
+
 	/**
 	 * Returns a context map for accessing attributes about the state of the current request. These attributes may be
 	 * used to influence flow execution behavior.

spring-webflow/src/main/java/org/springframework/webflow/execution/View.java

@@ -17,6 +17,8 @@ package org.springframework.webflow.execution;
 
 import java.io.IOException;
 
+import org.springframework.webflow.engine.ViewState;
+
 /**
  * Allows a client to participate in flow execution. Encapsulates behavior to send the client an appropriate response
  * and handle the resulting event once the client responds.
@@ -77,4 +79,11 @@ public interface View {
 	 */
 	public Object getUserEventState();
 
+	/**
+	 * Saves any state associated with this view out to view scope. Called when exiting a {@link ViewState} to allow for
+	 * any changes applied after postback processing to be captured and reflected when going back. Can be a no-op for
+	 * views that store no view state.
+	 */
+	public void saveState();
+
 }

spring-webflow/src/main/java/org/springframework/webflow/mvc/view/AbstractMvcView.java

@@ -224,6 +224,10 @@ public abstract class AbstractMvcView implements View {
 		userEventProcessed = true;
 	}
 
+	public Object getUserEventState() {
+		return new ViewActionStateHolder(eventId, userEventProcessed, mappingResults);
+	}
+
 	public boolean hasFlowEvent() {
 		return userEventProcessed && !requestContext.getMessageContext().hasErrorMessages();
 	}
@@ -235,8 +239,8 @@ public abstract class AbstractMvcView implements View {
 		return new Event(this, getEventId(), requestContext.getRequestParameters().asAttributeMap());
 	}
 
-	public Object getUserEventState() {
-		return new ViewActionStateHolder(eventId, userEventProcessed, mappingResults);
+	public void saveState() {
+
 	}
 
 	public String toString() {

spring-webflow/src/main/java/org/springframework/webflow/test/MockRequestContext.java

@@ -33,10 +33,11 @@ import org.springframework.webflow.execution.Event;
 import org.springframework.webflow.execution.FlowExecutionContext;
 import org.springframework.webflow.execution.FlowSession;
 import org.springframework.webflow.execution.RequestContext;
+import org.springframework.webflow.execution.View;
 
 /**
- * Mock implementation of the <code>RequestContext</code> interface to facilitate standalone flow artifact (e.g.
- * action) unit tests.
+ * Mock implementation of the <code>RequestContext</code> interface to facilitate standalone flow artifact (e.g. action)
+ * unit tests.
  * 
  * @see org.springframework.webflow.execution.RequestContext
  * @see org.springframework.webflow.execution.Action
@@ -60,6 +61,8 @@ public class MockRequestContext implements RequestContext {
 
 	private Transition currentTransition;
 
+	private View currentView;
+
 	/**
 	 * Convenience constructor that creates a new mock request context with the following defaults:
 	 * <ul>
@@ -176,6 +179,10 @@ public class MockRequestContext implements RequestContext {
 		return currentTransition;
 	}
 
+	public View getCurrentView() {
+		return currentView;
+	}
+
 	public MutableAttributeMap getAttributes() {
 		return attributes;
 	}
@@ -240,6 +247,14 @@ public class MockRequestContext implements RequestContext {
 		this.currentTransition = transition;
 	}
 
+	/**
+	 * Set the current view in this request context.
+	 * @param currentView the current view
+	 */
+	public void setCurrentView(View currentView) {
+		this.currentView = currentView;
+	}
+
 	/**
 	 * Set a request context attribute.
 	 * @param attributeName the attribute name

spring-webflow/src/main/java/org/springframework/webflow/test/MockViewFactoryCreator.java

@@ -95,6 +95,10 @@ class MockViewFactoryCreator implements ViewFactoryCreator {
 			return viewId;
 		}
 
+		public void render() throws IOException {
+			context.getExternalContext().getResponseWriter().write(viewId);
+		}
+
 		public boolean userEventQueued() {
 			return hasFlowEvent();
 		}
@@ -103,6 +107,10 @@ class MockViewFactoryCreator implements ViewFactoryCreator {
 			// TODO - implement me as appropriate for a test environment
 		}
 
+		public Object getUserEventState() {
+			return null;
+		}
+
 		public boolean hasFlowEvent() {
 			return context.getRequestParameters().contains("_eventId");
 		}
@@ -111,12 +119,8 @@ class MockViewFactoryCreator implements ViewFactoryCreator {
 			return new Event(this, context.getRequestParameters().get("_eventId"));
 		}
 
-		public Object getUserEventState() {
-			return null;
-		}
+		public void saveState() {
 
-		public void render() throws IOException {
-			context.getExternalContext().getResponseWriter().write(viewId);
 		}
 
 		public String toString() {

spring-webflow/src/test/java/org/springframework/webflow/engine/StubViewFactory.java

@@ -59,5 +59,9 @@ public class StubViewFactory implements ViewFactory {
 			return new Event(this, context.getExternalContext().getRequestParameterMap().get("_eventId"));
 		}
 
+		public void saveState() {
+
+		}
+
 	}
 }

spring-webflow/src/test/java/org/springframework/webflow/engine/model/AbstractModelTests.java

@@ -52,6 +52,12 @@ public class AbstractModelTests extends TestCase {
 		assertEquals(null, obj.merge(child, parent));
 	}
 
+	public void testMergeModel() {
+		AttributeModel child = new AttributeModel("foo", "bar");
+		AttributeModel parent = new AttributeModel("foo", "baz");
+
+	}
+
 	public void testListMerge() {
 		AbstractModel obj = new PersistenceContextModel();
 		LinkedList child = new LinkedList();