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Apache Struts 2 Documentation
Message Store Interceptor
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An interceptor to store a ValidationAware action's messages / errors and field errors into HTTP Session, such that it will be retrievable at a later stage. This allows the action's message / errors and field errors to be available longer that just the particular HTTP request.

If no session exists, nothing will be stored and can be retrieved later. In other terms, the application is responsible to open the session.

In the STORE mode, the interceptor will store the ValidationAware action's message / errors and field errors into HTTP session.

In the RETRIEVE mode, the interceptor will retrieve the stored action's message / errors and field errors and put them back into the ValidationAware action.

In the AUTOMATIC mode, the interceptor will always retrieve the stored action's message / errors and field errors and put them back into the [ValidationAware] action, and after Action execution, if the Result is an instance of ServletRedirectResult, the action's message / errors and field errors into automatically be stored in the HTTP session..

The interceptor does nothing in the NONE mode, which is the default.

The operation mode could be switched using:

1. Setting the interceptor parameter eg.

   xml<action name="submitApplication" ...> <interceptor-ref name="store"/> <param name="operationMode">STORE</param> </interceptor-ref> <interceptor-ref name="defaultStack" /> .... </action>

2. Through request parameter `allowRequestParameterSwitch` must be 'true' which is the default

   the request will have the operation mode in 'STORE' http://localhost:8080/context/submitApplication.action?operationMode=STORE

## Parameters

- `allowRequestParameterSwitch` - To enable request parameter that could switch the operation mode of this interceptor.
- `requestParameterSwitch` - The request parameter that will indicate what mode this interceptor is in.
- `operationMode` - The operation mode this interceptor should be in (either STORE, RETRIEVE, AUTOMATIC, or NONE). NONE being the default.

## Extending the Interceptor

There is no known extensions.

## Examples

xml<action name="submitApplication" ....> <interceptor-ref name="store"> <param name="operationMode">STORE</param> </interceptor-ref> <interceptor-ref name="defaultStack" /> <result name="input" type="redirectAction">applicationFailed</result> <result type="dispatcher">applicationSuccess.jsp</result> </action> <action name="applicationFailed" ....> <interceptor-ref name="store"> <param name="operationMode">RETRIEVE</param> </interceptor-ref> <result>applicationFailed.jsp</result> </action>

With the example above, submitApplication.action will have the action messages / errors / field errors stored in the HTTP Session. Later when needed, (in this case, when applicationFailed.action is fired, it will get the action messages / errors / field errors stored in the HTTP Session and put them back into the action.