Class RenderTool
- Direct Known Subclasses:
ViewRenderTool
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.generic.RenderTool"> <property name="parseDepth" 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 may be used in any scope, however, the context provided
for the eval(String)
and recurse(String)
methods
will only be current if the tool is request scoped. If application or
session scoped, then the context will be the same one set at the time
of the tool's first use. In such a case, each call to eval(String) or
recurse(String) will by default create a new Context that wraps the
configured one to prevent modifications to the configured Context
(concurrent or otherwise). If you wish to risk it and accrete changes
then you can relax the thread-safety by setting the 'forceThreadSafe'
property to 'false'.
Of course none of the previous paragraph likely applies if you are
not using the core tool management facilities or if you stick to the
eval(Context,String)
and recurse(Context,String)
methods. :)
This tool by default will catch and log any exceptions thrown during rendering and instead return null in such cases. It also limits recursion, by default, to 20 cycles, to prevent infinite loops. Both settings may be configured to behave otherwise.
- Version:
- $Revision: 671010 $ $Date: 2008-06-23 20:40:41 -0700 (Mon, 23 Jun 2008) $
- Author:
- Nathan Bubna
-
Field Summary
FieldsModifier and TypeFieldDescriptionprivate boolean
private org.apache.velocity.context.Context
static final int
The maximum number of loops allowed when recursing.private org.apache.velocity.app.VelocityEngine
private boolean
static final String
Deprecated.static final String
static final String
Deprecated.private static final String
private int
Fields inherited from class org.apache.velocity.tools.generic.SafeConfig
LOCK_CONFIG_KEY, OLD_LOCK_CONFIG_KEY, SAFE_MODE_KEY
-
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected void
configure
(ValueParser parser) Looks for deprecated parse depth and catch.exceptions properties, as well as any 'forceThreadSafe' setting.private void
private void
Evaluates a String containing VTL using the context passed to thesetVelocityContext(org.apache.velocity.context.Context)
method.Evaluates a String containing VTL using the current context, and returns the result as a String.boolean
Returnstrue
if this render() and eval() methods will catch exceptions thrown during rendering.int
Get the maximum number of loops allowed when recursing.protected String
internalEval
(org.apache.velocity.context.Context ctx, String vtl) protected String
internalRecurse
(org.apache.velocity.context.Context ctx, String vtl, int count) Recursively evaluates a String containing VTL using the current context, and returns the result as a String.Recursively evaluates a String containing VTL using the current context, and returns the result as a String.void
setCatchExceptions
(boolean catchExceptions) Sets whether or not the render() and eval() methods should catch exceptions during their execution or not.void
setParseDepth
(int depth) Set the maximum number of loops allowed when recursing.void
setVelocityContext
(org.apache.velocity.context.Context context) 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 org.apache.velocity.tools.generic.SafeConfig
configure, isConfigLocked, isSafeMode, setLockConfig, setSafeMode
-
Field Details
-
DEFAULT_PARSE_DEPTH
public static final int DEFAULT_PARSE_DEPTHThe maximum number of loops allowed when recursing.- Since:
- VelocityTools 1.2
- See Also:
-
KEY_PARSE_DEPTH
Deprecated.- See Also:
-
KEY_CATCH_EXCEPTIONS
Deprecated.- See Also:
-
KEY_FORCE_THREAD_SAFE
- See Also:
-
LOG_TAG
- See Also:
-
engine
private org.apache.velocity.app.VelocityEngine engine -
context
private org.apache.velocity.context.Context context -
parseDepth
private int parseDepth -
catchExceptions
private boolean catchExceptions -
forceThreadSafe
private boolean forceThreadSafe
-
-
Constructor Details
-
RenderTool
public RenderTool()
-
-
Method Details
-
configure
Looks for deprecated parse depth and catch.exceptions properties, as well as any 'forceThreadSafe' setting.- Overrides:
configure
in classSafeConfig
-
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
-
setVelocityContext
public void setVelocityContext(org.apache.velocity.context.Context context) -
getParseDepth
public int getParseDepth()Get the maximum number of loops allowed when recursing.- Since:
- VelocityTools 1.2
-
setCatchExceptions
public void setCatchExceptions(boolean catchExceptions) Sets whether or not the render() and eval() methods should catch exceptions during their execution or not.- Since:
- VelocityTools 1.3
-
getCatchExceptions
public boolean getCatchExceptions()Returnstrue
if this render() and eval() methods will catch exceptions thrown during rendering.- Since:
- VelocityTools 1.3
-
eval
Evaluates a String containing VTL using the context passed to the
setVelocityContext(org.apache.velocity.context.Context)
method. If this tool is request scoped, then this will be the current context and open to modification by the rendered VTL. If application or session scoped, the context will be a new wrapper around the configured context to protect it from modification. The results of the rendering are returned as a String. By default,null
will be returned when this throws an exception. This evaluation is not recursive.- Parameters:
vtl
- the code to be evaluated- Returns:
- the evaluated code as a String
- Throws:
Exception
-
recurse
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.
- Parameters:
vtl
- the code to be evaluated- Returns:
- the evaluated code as a String
- Throws:
Exception
- See Also:
-
eval
Evaluates a String containing VTL using the current context, and returns the result as a String. By default if this fails, then
null
will be returned, though this tool can be configured to let Exceptions pass through. This evaluation is not recursive.- Parameters:
ctx
- the current Contextvtl
- the code to be evaluated- Returns:
- the evaluated code as a String
- Throws:
Exception
-
internalEval
- Throws:
Exception
-
recurse
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 Contextvtl
- the code to be evaluated- Returns:
- the evaluated code as a String
- Throws:
Exception
-
internalRecurse
protected String internalRecurse(org.apache.velocity.context.Context ctx, String vtl, int count) throws Exception - Throws:
Exception
-
debug
-
debug
-