org.apache.velocity.tools.view
Class ViewRenderTool

java.lang.Object
  org.apache.velocity.tools.generic.AbstractLockConfig
      org.apache.velocity.tools.generic.RenderTool
          org.apache.velocity.tools.view.ViewRenderTool

@InvalidScope(value={"application","session"})
public class ViewRenderTool
extends RenderTool

This tool expose methods to evaluate the given strings as VTL (Velocity Template Language) and automatically using the current context.

 Example of eval():
      Input
      -----
      #set( $list = [1,2,3] )
      #set( $object = '$list' )
      #set( $method = 'size()' )
      $render.eval("${object}.$method")

      Output
      ------
      3

 Example of recurse():
      Input
      -----
      #macro( say_hi )hello world!#end
      #set( $foo = '#say_hi()' )
      #set( $bar = '$foo' )
      $render.recurse('$bar')

      Output
      ------
      hello world!


 Toolbox configuration:
 <tools>
   <toolbox scope="request">
     <tool class="org.apache.velocity.tools.view.ViewRenderTool">
       <property name="parse.depth" type="number" value="10"/>
     </tool>
   </toolbox>
 </tools>
 

Ok, so these examples are really lame. But, it seems like someone out there is always asking how to do stuff like this and we always tell them to write a tool. Now we can just tell them to use this tool.

This tool is NOT meant to be used in either application or session scopes of a servlet environment.

Since:

VelocityTools 2.0

Version:

$Revision: 591088 $ $Date: 2007-11-01 10:11:41 -0700 (Thu, 01 Nov 2007) $

Author:

Nathan Bubna

Field Summary

private org.apache.velocity.context.Context

context

Fields inherited from class org.apache.velocity.tools.generic.RenderTool

DEFAULT_PARSE_DEPTH, KEY_CATCH_EXCEPTIONS, KEY_FORCE_THREAD_SAFE, KEY_PARSE_DEPTH

Fields inherited from class org.apache.velocity.tools.generic.AbstractLockConfig

LOCK_CONFIG_KEY, OLD_LOCK_CONFIG_KEY

Constructor Summary

ViewRenderTool()

Method Summary

java.lang.String	eval(java.lang.String vtl) Evaluates a String containing VTL using the current context, and returns the result as a String.
java.lang.String	recurse(java.lang.String vtl) Recursively evaluates a String containing VTL using the current context, and returns the result as a String.
void	setVelocityContext(org.apache.velocity.context.Context context) Sets the current Context.

Methods inherited from class org.apache.velocity.tools.generic.RenderTool

configure, eval, getCatchExceptions, getParseDepth, internalEval, internalRecurse, recurse, setCatchExceptions, setParseDepth, setVelocityEngine

Methods inherited from class org.apache.velocity.tools.generic.AbstractLockConfig

configure, isConfigLocked, setLockConfig

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

context

private org.apache.velocity.context.Context context

Constructor Detail

ViewRenderTool

public ViewRenderTool()

Method Detail

setVelocityContext

public void setVelocityContext(org.apache.velocity.context.Context context)

Sets the current Context. This is required for this tool to operate and will throw a NullPointerException if this is not set or is set to null.

Overrides:

setVelocityContext in class RenderTool

eval

public java.lang.String eval(java.lang.String vtl)
                      throws java.lang.Exception

Evaluates a String containing VTL using the current context, and returns the result as a String. If this fails, then null will be returned. This evaluation is not recursive.

Overrides:

eval in class RenderTool

Parameters:

vtl - the code to be evaluated

Returns:

the evaluated code as a String

Throws:

java.lang.Exception

recurse

public java.lang.String recurse(java.lang.String vtl)
                         throws java.lang.Exception

Recursively evaluates a String containing VTL using the current context, and returns the result as a String. It will continue to re-evaluate the output of the last evaluation until an evaluation returns the same code that was fed into it.

Overrides:

recurse in class RenderTool

Parameters:

vtl - the code to be evaluated

Returns:

the evaluated code as a String

Throws:

java.lang.Exception

See Also:

RenderTool.eval(String)