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 exposes methods to evaluate the given strings as VTL (Velocity Template Language) using the given context.

NOTE: These examples assume you have placed an instance of the current context within itself as 'ctx'. And, of course, the RenderTool is assumed to be available as 'render'.

 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: 321227 $ $Date: 2005-10-14 14:55:18 -0700 (Fri, 14 Oct 2005) $

Author:

Nathan Bubna

Field Summary

static int	DEFAULT_PARSE_DEPTH The maximum number of loops allowed when recursing.
private org.apache.velocity.app.VelocityEngine	engine
private static java.lang.String	LOG_TAG
private int	parseDepth

Constructor Summary

RenderTool()

Method Summary

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.
int	getParseDepth() Get the maximum number of loops allowed when recursing.
protected java.lang.String	internalRecurse(org.apache.velocity.context.Context ctx, java.lang.String vtl, int count)
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.
void	setParseDepth(int depth) Set the maximum number of loops allowed when recursing.
void	setVelocityEngine(org.apache.velocity.app.VelocityEngine ve) Allow user to specify a VelocityEngine to be used in place of the Velocity singleton.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PARSE_DEPTH

public static final int DEFAULT_PARSE_DEPTH

The maximum number of loops allowed when recursing.

Since:

VelocityTools 1.2

See Also:

Constant Field Values

LOG_TAG

private static final java.lang.String LOG_TAG

See Also:

Constant Field Values

engine

private org.apache.velocity.app.VelocityEngine engine

parseDepth

private int parseDepth

Constructor Detail

RenderTool

public RenderTool()

Method Detail

setVelocityEngine

public void setVelocityEngine(org.apache.velocity.app.VelocityEngine ve)

Allow user to specify a VelocityEngine to be used in place of the Velocity singleton.

setParseDepth

public void setParseDepth(int depth)

Set the maximum number of loops allowed when recursing.

Since:

VelocityTools 1.2

getParseDepth

public int getParseDepth()

Get the maximum number of loops allowed when recursing.

Since:

VelocityTools 1.2

eval

public 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

Throws:

java.lang.Exception

recurse

public 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 or the number of recursive loops exceeds the set parse depth.

Parameters:

ctx - the current Context

vtl - the code to be evaluated

Returns:

the evaluated code as a String

Throws:

java.lang.Exception

internalRecurse

protected java.lang.String internalRecurse(org.apache.velocity.context.Context ctx,
                                           java.lang.String vtl,
                                           int count)
                                    throws java.lang.Exception

Throws:

java.lang.Exception