@DefaultKey(value="render") @InvalidScope(value="session") public class RenderTool extends SafeConfig
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.
Modifier and Type | Field and Description |
---|---|
static int |
DEFAULT_PARSE_DEPTH
The maximum number of loops allowed when recursing.
|
static String |
KEY_CATCH_EXCEPTIONS
Deprecated.
|
static String |
KEY_FORCE_THREAD_SAFE |
static String |
KEY_PARSE_DEPTH
Deprecated.
|
LOCK_CONFIG_KEY, log, LOGGER_NAME_KEY, SAFE_MODE_KEY, USE_CLASS_LOGGER_KEY
Constructor and Description |
---|
RenderTool() |
Modifier and Type | Method and Description |
---|---|
protected void |
configure(ValueParser parser)
Looks for deprecated parse depth and catch.exceptions properties,
as well as any 'forceThreadSafe' setting.
|
String |
eval(org.apache.velocity.context.Context ctx,
String vtl)
Evaluates a String containing VTL using the current context,
and returns the result as a String.
|
String |
eval(String vtl)
Evaluates a String containing VTL using the context passed
to the
setVelocityContext(org.apache.velocity.context.Context) method. |
boolean |
getCatchExceptions()
Returns
true if this render() and eval() methods will
catch exceptions thrown during rendering. |
int |
getParseDepth()
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) |
String |
recurse(org.apache.velocity.context.Context ctx,
String vtl)
Recursively evaluates a String containing VTL using the
current context, and returns the result as a String.
|
String |
recurse(String vtl)
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.
|
configure, getLog, initLogger, isConfigLocked, isSafeMode, setLockConfig, setSafeMode
public static final int DEFAULT_PARSE_DEPTH
@Deprecated public static final String KEY_PARSE_DEPTH
@Deprecated public static final String KEY_CATCH_EXCEPTIONS
public static final String KEY_FORCE_THREAD_SAFE
protected void configure(ValueParser parser)
configure
in class SafeConfig
parser
- configuration valuespublic void setVelocityEngine(org.apache.velocity.app.VelocityEngine ve)
ve
- VelocityEngine instancepublic void setParseDepth(int depth)
depth
- parse depthpublic void setVelocityContext(org.apache.velocity.context.Context context)
context
- Velocity contextpublic int getParseDepth()
public void setCatchExceptions(boolean catchExceptions)
catchExceptions
- whether to catch exceptionspublic boolean getCatchExceptions()
true
if this render() and eval() methods will
catch exceptions thrown during rendering.public String eval(String vtl) throws Exception
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.
vtl
- the code to be evaluatedException
- if womething went wrongpublic String recurse(String vtl) throws 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.
vtl
- the code to be evaluatedException
- if womething went wrongeval(String)
public String eval(org.apache.velocity.context.Context ctx, String vtl) throws Exception
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.
ctx
- the current Contextvtl
- the code to be evaluatedException
- if womething went wrongprotected String internalEval(org.apache.velocity.context.Context ctx, String vtl) throws Exception
Exception
public String recurse(org.apache.velocity.context.Context ctx, String vtl) throws 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.
ctx
- the current Contextvtl
- the code to be evaluatedException
- if womething went wrongCopyright © 2002–2018 The Apache Software Foundation. All rights reserved.