JSF components have many attributes which control how they are ultimately rendered, such as: required, disabled, rendered, maxsize, reRender, etc. These attributes are typically initialized with constants or expressions in individual facelets. However, this scatters these business rules across the code base. Taylor provides a simple alternative.

Contents 1 Goal 2 Rule Access 3 Rule Defintion 3.1 Resource Bundle Based Rules 3.1.1 Global Rules 3.1.2 View Specific Rules 3.1.3 Context Variables 3.2 Annotation Based Rules 3.3 Configuration

Goal

• Define rules in a single location instead of spread across many facelets
• Reuse rules across facelets
• Leverage Seam's support for expression language in resource bundles
• Leverage existing rules defined in entity beans via annotations

Rule Access

• Rules are retrieved using the TaylorFunctions library
• The library uses the view id, class name, and property name to look up the rule in a resource bundle

<h:inputText value="#{product.productNumber}"
	rendered="#{t:rendered(product, 'productNumber')}"
	disabled="#{t:disabled(product, 'productNumber')}" 
/>

• More Examples
  • input.xhtml
  • Tags

Rule Defintion

Resource Bundle Based Rules

• <project-ejb>/src/main/resources/rules.properties
• Not regenerated by Taylor MDA

Global Rules

• <classSimpleName>.<propertyName>.<rule>=expression

Product.editable=#{product.unapproved}
Product.productNumber.rendered=#{true}
Product.productNumber.disabled=#{!s:hasRole('ProductAdmin')}
Product.discounts.rendered=#{product.discounted}

View Specific Rules

• <view.id>.<classSimpleName>.<propertyName>.<rule>=expression
• JSF View Id with / replaced with . and no extension
  • /jsf/ProductWizard.xhtml = jsf.ProductWizard

jsf.ProductWizard.Product.productNumber.disabled=#{true}
jsf.ProductWizard.Product.type.reRender=optionsPanel

Context Variables

• The context variables used in the expressions must be initialized

• Factory option

   @Factory('product')
   public Product initEntity() {
      return getInstance();
   }

• Out-jection option

   @Out 
   private Product product;

Annotation Based Rules

Some rules are not specific to the presentation layer, but still play a role. These are modeled using stereotypes and generated into entity beans as annotations.

TaylorFunctions will use reflection to derive the presentation rule.

• t:required - @Required
• t:length - @Length, @Column
• t:min - @Min, @Range
• t:max - @Max, @Range
• t:hasPermission - @Premission

Configuration

• <project-ejb>/src/main/resources/rules.properties
• components.xml

<core:resource-loader>
	<core:bundle-names>
		<value>application</value>
		<value>messages</value>
		<value>rules</value>
	</core:bundle-names>
</core:resource-loader>