Apple WebObjects 3.5 Manual do Utilizador descarregar pdf (Página 52)

Chapter 3 Common Methods

Invoking an Action

The second phase of the request-response loop involves

invokeActionForRequest:inContext:

. WebObjects forwards this method from object to

object until it is handled by the dynamic element associated with the user action

(typically, a submit button, a hyperlink, and active image, or a form).

Use

invokeActionForRequest:inContext: if you want to return a page other than the one

requested. This scenario might occur if the user requests a page that has a

dependency on another page that the user must ﬁll out ﬁrst. The user might, for

example, ﬁnish ordering items from a catalog application and want to go to a

fulﬁllment page but ﬁrst have to supply credit card information.

The following example, implemented in

Session.wos, returns a “CreditCard” page

if the user hasn’t supplied this information yet:

// WebScript example

- invokeActionForRequest:request inContext:context {

id creditPage;

id responsePage = [super invokeActionForRequest:request

inContext:context];

id nameOfNextPage = [responsePage name];

if ([self verified]==NO &&

[nameOfNextPage isEqual:@"Fulfillment"]) {

creditPage = [[self application]

pageWithName:@"CreditCard"];

[creditPage setNameOfNextPage:nameOfNextPage];

return creditPage;

}

return responsePage;

}

//Java example

public Element invokeActionForRequest(Request request, Context contenxt)

{

Component creditPage;

Component responsePage = super.invokeActionForRequest(request,

context);

String nameOfNextPage = responsePage.name();

if (verified()==false &&

(nameOfNextPage.compareTo("Fulfillment") == 0) {

creditPage = application().pageWithName("CreditCard");

creditPage.setNameOfNextPage(nameOfNextPage);

return creditPage;

}

return responsePage;

}

When the application receives a request for a new page (say, a fulﬁllment page),

the session object determines whether or not the user has supplied valid credit-

card data by checking the value of its

veriﬁed variable. If the value of veriﬁed is NO,

the session object returns the “CreditCard” component. As shown in the

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