Common use case for stranded messages in MessageStoreInterceptor
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Key: WW-1831
URL: https://issues.apache.org/struts/browse/WW-1831
Project: Struts 2
Issue Type: Improvement
Components: Interceptors
Affects Versions: 2.0.6
Reporter: Jasper Rosenberg
I have what I think would be a pretty common use case for the
MessageStoreInterceptor where, under some circumstances, messages could be left
in the session, taking up memory unncessarily.
The sample use case is that when someone submits an email change, on success I
want to redirect them back to their home action, passing any messages (i.e.
"Your email has been successfully changed") along for display. I used to do
this with action chaining which worked but was sub-optimal since the user would
end up back at their home page with an url like "updateEmail.action" rather
than "home.action".
MessageStoreInterceptor seems like the right solution for this case as now I
can have the updateEmail store the message, redirect to the home page, and then
have home page retrieve it:
<action name="home"
class="com.mycompany.action.HomeAction">
<result>home.ftl</result>
<interceptor-ref name="store">
<param name="operationMode">RETRIEVE</param>
</interceptor-ref>
<interceptor-ref name="basicStack"/>
</action>
<action name="updateEmail"
class="com.mycompany.action.ChangeEmailAction" method="updateEmail">
<result type="redirect-action">
<param name="actionName">home</param>
</result>
<result name="input">editEmail.ftl</result>
<interceptor-ref name="store">
<param name="operationMode">STORE</param>
</interceptor-ref>
<interceptor-ref name="validationStack"/>
</action>
The problem is the case when the result of updateEmail is "input" rather than
"success". In this case, I just redisplay the change email form, but any
validation errors will have been stored in the session. If the user then
navigates away or closes the browser, these messages will be stranded in the
session.
I think there is a pretty simple fix for this:
In MessageStoreInterceptor.before(), simply move the lines:
session.remove(actionErrorsSessionKey);
session.remove(actionMessagesSessionKey);
session.remove(fieldErrorsSessionKey);
out of the nested ifs so that they are always the last operations in the method.
This will handle any case other than a redirect/chain to an action that doesn't
have the interceptor at all (which can't be helped).
Another option to this is to explictly support an additional parameter for the
Interceptor like "clearStoredMessages" which defaults to false, but if true
always calls the session.remove()s at the end of the before().
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