If (Tapestry API

java.lang.Object
- org.apache.tapestry5.corelib.base.AbstractConditional
- - org.apache.tapestry5.corelib.components.If

public class If
extends AbstractConditional

Conditionally renders its body. May render its tag and any informal parameters.

Component Parameters
Name	Type	Flags	Default Prefix
else	org.apache.tapestry5.Block		literal
else	An alternate org.apache.tapestry5.Block to render if org.apache.tapestry5.corelib.base.AbstractConditional#test() is false. The default, null, means render nothing in that situation.
negate	boolean		prop
negate	Optional parameter to invert the test. If true, then the body is rendered when the test parameter is false (not true).
test	boolean	Required	prop
test	If true, then the body of the If component is rendered. If false, the body is omitted.

Examples

Start.tml

<html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_3.xsd" xmlns:p="tapestry:parameter">
    <body>
        <h1>Welcome!</h1>

        <t:if test="user">
            Welcome back, ${user.firstName}
            <p:else>
                <t:pagelink page="login">Login</t:pagelink> /
                <t:pagelink page="register">Register</t:pagelink>
            </p:else>
        </t:if>
        
        . . .

</html>

Here, the main text is rendered if the user is logged in (the user property will be non-null after the user logs in). Otherwise, links to a login and register page are rendered.

Notes

Tapestry has many built in coercions to boolean:

String: True if non-blank and not the literal string "false" (case insensitive)
Number: True if non-zero
Collection: True if non-empty
Object: True (as long as it's not null)

Constructor Summary

Constructors
Constructor and Description

If()

Constructors
Constructor and Description
`If()`

Method Summary

Methods
Modifier and Type	Method and Description
`protected boolean`	`test()` Performs the test via the parameters; return true to render the body of the component, false to render the else block (or nothing).

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - If
```
public If()
```
- Method Detail
  - test
```
protected boolean test()
```
    Description copied from class: AbstractConditional
    
    Performs the test via the parameters; return true to render the body of the component, false to render the else block (or nothing).
    
    Specified by:
    
    test in class AbstractConditional
    
    Returns:
    test parameter (if negate is false), or test parameter inverted (if negate is true)

Class If

Examples

Start.tml

Notes

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

If

Method Detail

test