org.apache.velocity.tools.generic
Class RenderTool

java.lang.Object
  |
  +--org.apache.velocity.tools.generic.RenderTool

Direct Known Subclasses:

ViewRenderTool

public class RenderTool

extends java.lang.Object

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

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

      Output
      ------
      3
 
 Example of recurse():
      Input
      -----
      #macro( say_hi )hello world!#end
      #set( $foo = '#say_hi()' )
      #set( $bar = '$foo' )
      $render.recurse($ctx, $bar)

      Output
      ------
      hello world!

 

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 safe (and optimized) for use in the application scope of a servlet environment.

Version:

$Revision: 1.2 $ $Date: 2003/05/28 00:17:15 $

Author:

Nathan Bubna

Field Summary

private static java.lang.String

LOG_TAG

Constructor Summary

RenderTool()
Constructs a new instance

Method Summary

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

Methods inherited from class java.lang.Object

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

Field Detail

LOG_TAG

private static final java.lang.String LOG_TAG

See Also:

Constant Field Values

Constructor Detail

RenderTool

public RenderTool()

Constructs a new instance

Method Detail

eval

public static java.lang.String eval(org.apache.velocity.context.Context ctx,
                                    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.

Parameters:

ctx - the current Context

vtl - the code to be evaluated

Returns:

the evaluated code as a String

java.lang.Exception

recurse

public static java.lang.String recurse(org.apache.velocity.context.Context ctx,
                                       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.

FIXME? add a parse-depth to prevent infinite recursion?

Parameters:

ctx - the current Context

vtl - the code to be evaluated

Returns:

the evaluated code as a String

java.lang.Exception