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oracle adf workshop

Notes:


Using Expression Language

You can use a simple expression language (EL) to work with information. EL is part of JSP Standard Tag Library (JSTL), and it defines a standard syntax for accessing dynamic values without using Java scriptlets in JSPs. The standard syntax is #{object.attribute} for a JSF expression, or ${expression} for a standard JSTL expression. Binding expressions can use either a $ or #prefix, but EL expressions in JSF pages can use only the # prefix.

At run time, a generic expression evaluator returns value of expressions, automating access to the individual objects and their properties without requiring code. You use EL expressions throughout an ADF Faces application to bind attributes to object values determined at run time.

The value of certain UI components (such as an input text component) are determined at run time by the value attribute. Though a component can have static text as its value, typically the value attribute contains an EL expression that the run-time infrastructure evaluates to determine what data to display. Because any attribute of a component (and not just the value attribute) can be assigned a value by using an EL expression, it is easy to build dynamic, data-driven user interfaces.

You can create EL expressions declaratively by using the JDeveloper Expression Builder. You can access the builder from the Property Inspector by selecting Expression Builder from the drop-down list of an attribute.