source/core-developers/message-store-interceptor.md

---
layout: default
title: Message Store Interceptor
parent:
    title: Interceptors
    url: interceptors.html
---

# Message Store Interceptor

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.