THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Parameters are defined by using the @Parameter @Parameter annotation on a private field.
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The component above can be referenced in another component or page template:
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<html t:type="layout" xmlns:t="http://tapestry.apache.org/schema/tapestry_5_1_0.xsd">
<p> Merry Christmas: <t:count end="3"> Ho! </t:count>
</p>
</html>
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The end attribute is used to bind the end parameter of the Count component. Here, it is being bound to the string value "3", which is automatically coerced by Tapestry into the int value, 3.
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Component parameters may also be bound using the @Component @Component annotation inside the component class.
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Only components whose class is annotated with @SupportsInformalParameters @SupportsInformalParameters will support informal parameters. Tapestry silently drops informal parameters that are specified for components that do not have this annotation.
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The default binding prefix for informal parameters depends on where the parameter binding is specified. If the parameter is bound inside a Java class, within the @Component @Component annotation, then the default binding prefix is "prop:". If the parameter is bound inside the component template, then the default binding prefix is "literal:". This reflects the fact that a parameter specified in the Java class, using the annotation, is most likely a computed value, whereas a value in the template should simply be copied, as is, into the result HTML stream.
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In rare cases, you may want to take different behaviors based on whether a parameter is bound or not. This can be accomplished by querying the component's resources, which can be injected into the component using the @Inject @Inject annotation:
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public class MyComponent
{
@Parameter
private int myParam;
@Inject
private ComponentResources resources;
@BeginRender
void setup()
{
if (resources.isBound("myParam"))
{
. . .
}
}
}
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In Tapestry 5.1 and later, you may use the publishParameters attribute of the @Component @Component annotation. List one or more parameters separated by commas: those parameters of the inner/embedded component become parameters of the outer component. You should not define a parameter field in the outer component.
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