Component actions

A link or form calls a method on the component instance that rendered it:

<wo:link action="$showDetails">Details</wo:link>

public NGActionResults showDetails() {
	final DetailPage page = pageWithName( DetailPage.class );
	page.product = product;
	return page;
}

No URLs to design, nothing to parse, no state to save. The cost: actions need the user's session and the page kept in memory. For stable URLs, use routes.

What an action returns

Forms

<wo:form>
	<wo:textfield value="$name" />
	<wo:submit action="$save" value="Save" />
</wo:form>

public String name;

public NGActionResults save() {
	// name holds what was typed
	return null;
}

How it works

The action URL (/no/3.0.1.5) names the page (3) and the clicked element (0.1.5). On click, the page is taken from the session's page cache and run through the request–response loop:

1. takeValuesFromRequest: form fields set their bindings (only when there are form values).
2. invokeAction: the clicked element calls its action.
3. appendToResponse: the resulting page renders.

The page cache

• Holds a session's last 100 pages, so the back button works.
• An evicted page's actions answer "page not found"; an expired session shows a timeout page. Sessions expire after 60 idle minutes.
• One request at a time per page. Different pages run concurrently, so synchronize state shared between them yourself.

(TODO: cache size and session timeout aren't configurable yet.)

To update part of a page, see Partial page updates.