Apple WebObjects 3.5 Bedienungsanleitung PDF herunterladen (Seite 114)

Chapter 3 Creating a WebObjects Database Application

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2. Using the Display Group Options panel, assign talentDisplayGroup’s entity to

Talent.

Remember that to open the Display Group Options panel, simply

double-click the

talentDisplayGroup variable in the object browser. The icon

initially displayed next to the variable indicates that initialization

parameters have not yet been set.

3. Conﬁgure

talentDisplayGroup to sort its objects alphabetically (ascending)

lastName.

4. Conﬁgure it to fetch on load.

After you conﬁgure

talentDisplayGroup, the object browser shows a icon

next to the variable.

The Movies application uses a display group to provide Talent objects, but you

could fetch the Talent objects from the database without one. Display groups

provide a simple way to fetch, insert, update, and delete enterprise objects

without writing much, if any, code. To get ﬁner-grained control over these

operations, you can work directly with an EditingContext object. An editing

context can do everything a display group does and much more, but you have to

write more code to use one. For more information, see the EditingContext class

speciﬁcation in the Enterprise Objects Framework Reference.

Conﬁguring the Browser

In a way similar to the way you create bindings for a repetition, create your

browser’s bindings.

1. Bind

talentDisplayGroup.displayedObjects to the browser’s list attribute.

2. Bind

talent to the browser’s item attribute.

3. Bind

talent.lastName to the browser’s value attribute.

The

value attribute tells the browser what string to display. For each item in

its

list, the browser evaluates the item’s value.

The browser in the MovieDetails page should display the actors’ full

names, but there isn’t an attribute for full name. In the next section, you’ll

create a custom Talent class that implements a

fullName method, but for now

just use

talent.lastName as the value attribute.

A browser also has a

selections attribute that should be bound to a vector of

objects. A browser’s selection can be zero, one, or many objects; but in the

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