Apple WebObjects 3.5 Manual do Utilizador descarregar pdf (Página 51)

Request-Handling Methods

As you implement request-handling methods, you must invoke the

superclass’s implementation of the same methods. But consider where you

invoke it because it can affect the request, response, and context

information available at any given point. In short, you want to perform

certain tasks before

super is invoked and other tasks after super is invoked.

Taking Input Values From a Request

The takeValuesFromRequest:inContext: method is invoked during the ﬁrst phase of

the request-response loop, immediately after all of the objects involved in

the request have performed their

awake methods. When this phase

concludes, the request component has been initialized with the bindings

made in WebObjects Builder.

Override

takeValuesFromRequest:inContext: when you want to do one of the

following:

• Access information from the request or context object.

• Perform postprocessing on user input.

In the ﬁrst case, you can place your code before the message to

super. In the

second case, you must place your code after the message to

super. For

example, the following implementation of

takeValuesFromRequest:inContext:

records the kinds of browsers—user agents—from which requests are

made:

// WebScript example

- takeValuesFromRequest:request inContext:context {

id userAgent = [request headerForKey:@"user-agent"];

[self recordUserAgent:userAgent];

[super takeValuesFromRequest:request inContext:context];

}

The following example performs postprocessing. It takes the values for the

street, city, state, and zipCode variables and stores them in the address variable

formatted as a standard mailing address.

// WebScript example

- takeValuesFromRequest:request inContext:context {

[super takeValuesFromRequest:request inContext:context];

address = [NSString stringWithFormat:@"%@\n%@, %@ %@",

street, city, state, zipCode];

}

// Java example

public void takeValuesFromRequest(Request request, Context context) {

super.takeValuesFromRequest(request, context);

address = street + city + state + zipCode;

}

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