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You generally should not use the Template Expansion syntax, ${...}, within component parameter bindings. Doing so results in the property inside the braces being converted to an (immutable) string, and will therefore result in a runtime exception if your component needs to update the value (whenever the default or explicit binding prefix is prop: or var:, since such component parameters are two-way bindings).

<t:textfield t:id="color" value="color"/>

<t:textfield t:id="color" value="${color}"/>

The general rule is, only use the ${...} syntax in non-Tapestry-controlled locations in your template, such as in attributes of ordinary HTML elements and in plain-text areas of your template.

<img src="${context:images/banner.png}"/>

<img src="context:images/banner.png"/>

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In Tapestry 5.1 and later, you may use the publishParameters attribute of the @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.

<t:container xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd">
<t:pageLink t:id="link">Page Link</t:pageLink>
</t:container>

public class ContainerComponent{
@Component(id="link", 	publishParameters="page")
private PageLink link;
}

<t:ContainerComponent t:id="Container" t:page="About" />

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