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Excerpt
hiddentrue

a brief guide for learning Tapestry, designed for those who already know JavaServer Faces (JSF)

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This is a brief guide

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Tapestry for JSF Users

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This is Excerpta cheat sheet for learning Tapestry, designed for those who already know JavaServer Faces (JSF).

Because both JSF and Tapestry are component oriented frameworks designed to serve mostly the same kinds of problems in similar ways, developers who already know JSF will find it very easy to learn Tapestry. In fact, Facelets, the default view technology in JSF 2.0, was created specifically to give JSF a Tapestry-like templating capability, so Facelets users should feel right at home.

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Since almost all modern JSF applications use Facelets as their view technology, we assume the use of Facelets here when discussing JSF features.

...

Concepts & Terminology

JSF

Tapestry

Java class associated with a page or component

"Backing Bean"

"Component Class"

Component attributes/parameters

"attributes"

"parameters"

Common Attributes/Parameters

JSF

Tapestry

HTML Attribute used for invisible instrumentation

jsfc="someComponentType"

t:type="someComponentType"

CSS "class" attribute name

styleClass

class

Alternating "zebra" striped rows

rowclasses="class1,class2"

class="${cycle:class1,class2}" using cycle binding prefix, or with CSS: .rowClass:nth-child(even) {background-color: #e8e8e8;}

Output and Messages

JSF

Tapestry

Escaped HTML from property

<h:outputText value="myBean.myValue"/>

${myValue}

Raw HTML from property

#{myBean.myValue}

<t:outputRaw value="myValue"/>

Error messages

<h:message> and <h:messages>

<t:error> and <t:errors> (for forms) or <t:alerts>

Image display

<h:graphicImage>

use standard <img> tag, but see Assets

Conditionals and Looping

JSF

Tapestry

Render-time loop

<ui:repeat>

<t:loop>

Compile-time loop

<c:forEach>

<t:loop>

Conditional

<c:if test="#{myBean.myValue}">

<t:if test="myValue">

Conditional

<ui:fragment rendered="#{myBean.someCondition}"/>...</ui:fragment>

<t:if test="someCondition">...</t:if>

Switch

<c:choose><c:when ... ></c:choose>

See Switching Cases

Server-side comment

<ui:remove>

<t:remove>

Links and Buttons

JSF

Tapestry

Navigational link

<h:link outcome="nextpage.xhtml"/>

<t:pagelink page="nextpage"/>

Event-triggering link, without form submission

not available

<t:actionLink> or <t:eventLink>

Form submission link

<h:commandLink>

<t:linkSubmit>

Form submission button

<h:commandButton>

<t:submit>

Link to Javascript file

<h:outputScript>

<script> or use @Import in component class

Link to CSS file

<h:outputStylesheet>

<style> or use @Import in component class

Grids, Tables and Trees

JSF

Tapestry

Tabular data in <table>

<h:datatable>

<t:grid>

Table used for layout

<h:panelGrid> with <h:panelGroup>

use standard <table> tag

Hierarchical tree

depends on component library

<t:tree>

Form Tags/Components

JSF

Tapestry

Form

<h:form>

<t:form>

Single-line text input field

<h:inputText>

<t:textField>

Password field

<h:inputSecret>

<t:passwordfield>

Select menu

<h:selectOneMenu>

<t:select>

Checkbox

<h:selectBooleanCheckbox>

<t:checkbox>

Checkbox list

<h:selectManyCheckbox>

<t:checklist>

Radio button list

<h:selectOneRadio>

<t:radioGroup> with <t:radio>

Multiple select menu

<h:selectManyListbox>

not available (but see Palette and Checklist)

Hidden field

<h:inputHidden>

<t:hidden>

textarea tag

<h:inputTextarea>

<t:textArea>

Label tag

<h:outputLabel for="...">

<t:label for="...">

...

Faces templates and Tapestry templates are superficially quite similar.

Section
Column
Code Block
languagexml
titleJSF template (helloworld.xhtml)xml

<html xmlns="http://www.w3.org/1999/xhtml"
        xmlns:h="http://java.sun.com/jsf/html">
  <h:body>
    <p><h:outputText value="#{helloWorldBean.greeting} /></p>
  </h:body>
</html>
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Code Block
languagexml
titleTapestry template (HelloWorld.tml)xml

<html>
<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_4.xsd">
  <body>
    <p>${greeting}</p>
  </body>
</html>

...

  • The #{...} syntax in JSF does not encode the underlying string, so you have to use the <h:outputText> tag if your data may contain HTML reserved characters such as <, >, or &. In contrast, the ${...} syntax in Tapestry does encode the underlying string.
  • In JSF, backing beans are not necessarily related one-to-one with page templates. Often several templates use the same backing bean, and one template may reference multiple backing beans. In Tapestry, they are always related one-to-one, and therefore you don't have to specify which component class your ${...} expressions are referencing.
Section
Column
Code Block
languagejava
titleJSF Backing Bean (HelloWorldBean.java)java

@ManagedBean
@RequestScoped
public class HelloWorldBean {
    public String getGreeting() {
        return "Hello, World!";
    }
}
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Code Block
languagejava
titleTapestry page class (HelloWorld.java)java

public class HelloWorld {
    public String getGreeting() {
        return "Hello, World!";
    }
}

...

JSF uses the Unified Expression Language with the #{...} or ${...} syntax for accessing Backing Bean properties. For its part, Tapestry uses the ${...} syntax with a similar but more intentionally limited expression language called Property Expressions. Both allow easy access to properties via the usual JavaBean conventions, but with Tapestry you don't have to specify which class the expression starts at (because it always starts at the component class corresponding to the template). Some comparisons:

 

JSF Syntax

Tapestry Syntax

Property (calls getEmployeeName() or setEmployeeName())

#{employeeBean.employeeName}

${employeeName}

Boolean property (calls isHourly() or setHourly())

#{employeeBean.hourly}

${hourly}

Property chain

#{employeeBean.address.street}

${address.street}

Null-safe property chain

#{employeeBean.address.street}

${address?.street}

5th element in a List

#{employeeBean.employees[5].name}

${employees.get(5).name}

Negation

#{! employeeBean.hourly}

${! hourly}

Arithmetic & relational operators

+-*/% div mod

not available

Relational operators

== != ne < lt > gt <= le >= ge

not available

Ternary operator

#{myBean.foo < 0 ? 'bar' : 'baz'}

not available

Method calling

#{myBean.employees.size()}

${employees.size()}

Iterated Range

not avaialble

${1..10}

Iterated Range (calculated)

not avaialble

${1..groupList.size()}

List

not available

${ [ user.name, user.email, user.phone ] }

Map

not available

${ { 'id':'4039','type':'hourly' } }

...

Tapestry applications can use JSR 303 Bean Validation annotations that JSF users should be familiar with:

Code Block
java
languagejava

public class Employee {
    @Validate("required,minlength=2,maxlength=100")
    private String lastName;
    @NotNull @Email private String email;

...

Note that by default Tapestry does not save property values across the Post-Redirect-Get cycle. This means that you have to consider how (and whether) to persist property values from one page to the next. The usual solution is to either make the values part of the page's Activation Context (which means the values will be appended to the URL) or @Persist the properties the values in the session.

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