Templating

A component's template is HTML plus dynamic tags. Bindings on the tags connect to the component's Java class.

<p>Hello <wo:str value="$name" />!</p>

public class Hello extends NGComponent {

	public String name = "world";

	public Hello( NGContext context ) {
		super( context );
	}
}

Template files

In src/main/resources/components, named after the class:

• Hello.html, or
• Hello.wo/Hello.html (plus an optional Hello.wod)

No subfolders. A template without a class works too.

Dynamic tags

<wo:tagName binding1="$someKey" binding2="Some constant" />

• Always close the tag: </wo:tagName>, or />.
• The tag name is a short name (str), a simple class name (NGString, Hello) or a fully qualified one.

All built-in elements: Dynamic elements.

Binding values

No WebObjects @ operators, and no binding twice on one tag.

KeyValueCoding

KVC resolves a key like $name to a public method or field on the component. First match wins:

1. Methods: getName(), name(), isName(), then _getName(), _name(), _isName()
2. Fields: name, isName, _name, _isName

No match throws UnknownKeyException, shown as an error box in the page with a suggestion: "Did you mean 'name'?".

Forms set bindings on submit, through setName( value ) or the field name. Strings are converted when the target is a number.

In a keypath like $company.manager.name, each key resolves on the result of the previous one. A null anywhere makes the whole keypath null, without a NullPointerException. Setting through a null fails.

Maps aren't supported: $map.key doesn't read the map's entry (#36). To customise lookups, implement NGKeyValueCoding (valueForKey, takeValueForKey). From Java:

Object name = NGKeyValueCoding.Utility.valueForKey( user, "name" );
NGKeyValueCoding.Utility.takeValueForKey( user, "Jane", "name" );

Lookups are cached per class and key in production, not in development.

Coming from WebObjects: NGKeyValueCoding is Apple's NSKeyValueCoding, almost unchanged. There's no KeyValueCodingProtectedAccessor, so only public members are read. WO tries the underscored fields first (_name, _isName, name, isName), which only matters for a class with more than one public field for the same key.

Embedding components

<wo:Hello name="$user.firstName" />

A wrapper renders the content between its tags at <wo:content />:

<!-- Page.html -->
<body>
	<header>My site</header>
	<wo:content />
</body>

<wo:Page>
	<p>Inside the body, below the header.</p>
</wo:Page>

WOD files

Supported, for templates coming from WebObjects:

<webobject name="Greeting" />

Greeting : NGString {
	value = name;
}

Quoted values are constants, unquoted ones keypaths. Use engifer's element names (NGString or str), not WOString.

Directives

• <p:raw>…</p:raw>: output as is, no dynamic tags.
• <p:comment>…</p:comment>: left out of the output.