[Seaside] Question on page redirection

[Avi Bryant]

On Sun, 29 Dec 2002 tblanchard@mac.com wrote:

> When I've done WebObjects applications, I've overridden the method
> pageWithName in session to return the login page if the cookie auth
> token was missing.
>
> Whats the good bottleneck in seaside for trapping a request for a page
> and replacing it with a login page so that I don't have to replicate
> the test for credentials everywhere?

Funny, Julian and I were just talking about that last night.  There really
isn't a great place to do that right now.  One thing to do would be to
write a framing component that conditionally showed either your
application or the login page; ie, if your entry point component is
currently, say, ToddApp, then instead make it something like

WAComponent subclass: #ToddFrame
	instanceVariableNames: 'main login'
	classVariableNames: ''
	poolDictionaries: ''
	category: 'Foo'

initialize
  main := self containerFor: ToddApp new.
  login := ToddLogin new.

renderOn: html
  session hasUserInfo
   ifTrue: [html render: main]
   ifFalse: [html render: login]

The main problem with that approach is that the check doesn't happen until
the response phase - if somebody requests a URL generated while a user was
logged in, they can still trigger an action before they're asked to
authenticate themselves.

To prevent that, you'd probably want to override
WASession>>wrapContinuation:withReturnBlock:.  This method returns the
blocks/continuations that are effectively the request handlers.  You
probably want something like this:

wrapContinuation: aContinuation withReturnBlock: aBlock
  |continue|
  block := super wrapContinuation: aContinuation withReturnBlock: aBlock.
  ^ [:request |
    self hasUserInfo
      ifFalse: [|login|
               login := LoginPage new.
               login withContinuationDo: [login start]].
    continue threadSafeValue: request]


Need to run, so I'll explain that bit of code later...

Avi