[Seaside] Entry and Re-Entry from Legacy Rails App

[Ken Treis]

I'm working on adding a Seaside layer to one of my legacy systems  
(it's fun to call Rails "legacy", eh?). As I try to link back and  
forth from the old code to the new, I'm finding that I need my  
session state preserved across exits and entries.

As an example, I have built a hierarchy navigation component in  
Seaside, and it remembers the account you selected last time you used  
it. So each time I call the component, the hierarchy is still open to  
the last account that the user selected.

I'd love to use this from Rails, but each time I follow the link to / 
seaside/selectAccount, it starts me with a fresh session and I lose  
my old state. The cool remembering trick never gets to show its stuff.

The solution I've come up with is hackish, which is why I'm asking  
for input here. Essentially, I'm subclassing WAApplication and using  
the Rails cookie as the session key. That way, my old session can be  
found when the user re-enters Seaside.

This works for me, at this point. LegacyOverlay is a subclass of  
WAApplication:

> sessionCookieField
> 	^'_session_id'
>
> registerRequestHandler: anObject
> 	| key |
> 	(anObject isKindOf: Seaside.WASession)
> 		ifFalse: [^super registerRequestHandler: anObject].
> 	key := Seaside.WAExternalID
> 				fromString: (anObject currentRequest cookies at: self  
> sessionCookieField).
> 	self shouldCollectHandlers ifTrue: [self unregisterExpiredHandlers].
> 	self mutex critical:
> 			[handlersByKey at: key put: anObject.
> 			keysByHandler at: anObject put: key].
> 	^key
>
> handleDefaultRequest: aRequest
> 	| sessionKey existingSession |
> 	sessionKey := aRequest cookies at: self sessionCookieField
> 				ifAbsent: [^self redirectToLoginPage: aRequest].
> 	existingSession := handlersByKey at: (Seaside.WAExternalID  
> fromString: sessionKey)
> 				ifAbsent: [^super handleDefaultRequest: aRequest].
> 	^existingSession handleRequest: aRequest

Am I on the right track, or is there an easier way to accomplish  
this? Since I'm overlaying my Seaside app on an existing system, the  
app needs to behave as if it has multiple entry points. I just don't  
want it to start over every time it is entered.

For my account selection component, I'm just storing the last  
selected account in an instance variable in the session. That means  
that simply locating the previous session is enough to make my  
component do its magic. At some point I'd rather do something less  
"global", like an instance variable in a component that I instantiate  
once and repeatedly call, but I'm not familiar enough with the  
internals quite yet to make it work that way.

--
Ken Treis
Miriam Technologies, Inc.

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