Apple WebObjects 3.5 Tools And Techniques - Manual (Page 80)

Chapter 3 Working With Dynamic Elements
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the WOConditional’s contents are displayed. If condition is false (0), the contents
aren’t displayed.
condition can be bound to a variable or to method that returns a Boolean value.
(WebScript and Objective-C use the constants YES and NO ; Java uses true and false .)
To bind condition (or any other attribute that takes a Boolean) to a constant value,
enter YES or NO in the bindings Inspector.
To create a conditional, click in the toolbar.
Note: Any selected elements will be contained within the conditional.
To bind to a conditional, click a variable or method and drag to one of the
conditional’s outer icons. The Inspector appears, displaying the bindings for the
WOConditional, with the
condition attribute selected by default. Complete the
binding by clicking Connect Variable, or choose a different attribute to bind.
There is a shortcut for binding the condition attribute. Drag from a key in the
object browser to the binding box in the conditional.
Sometimes, you want the equivalent of an “if-then-else” structure; that is, “if
the condition is true, display this text; if not, display this other text.” To
accomplish this, you can use the
negate attribute. If negate is true, then the
contents of the conditional are displayed only if condition is false. To create an if-
then-else structure, do the following:
1. Create two WOConditionals.
2. Bind the condition attribute of both of them to the same variable or method.
3. Bind the negate attribute of the second one to YES (true).
By default, negate is false, so you do not explicitly need to bind the first
conditional’s negate attribute.
As with repetitions, you can “wrap” a conditional around a table row (see
“Repetitions”). When you do this, the conditional symbol doesn’t appear but
the row appears with a blue background.
Drag from the object browser to this box to bind the condition attribute
without opening the Inspector. The binding appears inside the box.
Contents of the conditional display if
condition is true.
Drag from the object browser to here
to bind (opensthe Inspector).