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https://issues.apache.org/jira/browse/VELOCITY-881?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16091033#comment-16091033
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pixiang.lq commented on VELOCITY-881:
-------------------------------------
At first, thank you for your answers Claude Brisson.
I have try to force a rendering with code like:
#if( "$some.reference" == 'some value')
but it still doesn't work, and the output was:
--------------------------
<bean class="MY_CLASS2">
<property name="MY_PROPERTY_NAME2">
<value>${provider.version}</value>
</property>
</bean>
--------------------------
I know "${deploy.domain} will always be null, since Velocity will first search
the context for a deploy property". But in our team property naming conventions
is "property.name", like "provider.version", rather than "property_name". So
"reference insertion handler" mechanism is a good way for us to replace the
value when velocity got value null.
"$foo.bar.baz would call the handler three times, which is not at all
desirable." In fact $foo.bar.baz would call the handler only one times and i
have debug to verify that.
-----------------------------------
public Object execute(Object o, InternalContextAdapter context) throws
MethodInvocationException {
if(this.referenceType == 4) {
return null;
} else {
{color:red}Object result = this.getVariableValue(context,
this.rootString);{color}
this.log.error(String.format("rootString:%s, result:%s",
this.rootString, result));
if(result == null && !this.strictRef) {
return EventHandlerUtil.invalidGetMethod(this.rsvc, context,
this.getDollarBang() + this.rootString, (Object)null, (String)null,
this.uberInfo);
} else {
........
At last, may be my suggestion is not good for performance in other scenes and
my be have another way to solute this. I fill it very strange that "reference
insertion handler" mechanism has give a way to replace the inserted value in
the template, but it not support to replace the reference in if statement.
> Even handler didn't work when the reference appear in #if statement
> -------------------------------------------------------------------
>
> Key: VELOCITY-881
> URL: https://issues.apache.org/jira/browse/VELOCITY-881
> Project: Velocity
> Issue Type: Bug
> Components: Engine
> Affects Versions: 1.7
> Environment: it a common case. It nothing to do with a specified
> environment
> Reporter: pixiang.lq
> Assignee: Claude Brisson
> Labels: easyfix
> Original Estimate: 2h
> Remaining Estimate: 2h
>
> My code like:
> ----------------------------------------------------------------
> public static void main(String[] args) {
> VelocityEngine ve = new VelocityEngine();
> ve.setProperty(Velocity.RESOURCE_LOADER, "class");
> ve.setProperty("class.resource.loader.class",
>
> "org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader");
> try {
> ve.init();
> Template tp = ve.getTemplate("my-template.xml");
> Context context = new VelocityContext();
> // add my event handler
> Map map = new HashMap<>();
> map.put("deploy.domain", "offline");
> map.put("deploy_domain", "offline");
> map.put("provider.version", "1.0.0");
> map.put("provider_version", "1.0.0");
> EventCartridge eventCartridge = new EventCartridge();
> eventCartridge.addEventHandler(new
> MyReferenceInsertionHandler(map));
> eventCartridge.attachToContext(context);
> StringWriter writer = new StringWriter();
> tp.merge(context, writer);
> System.out.println(writer.toString());
> } catch (Exception e) {
> e.printStackTrace();
> }
> }
> ----------------------------------------------------------------
> My template file to be converted by velocity like:
> ----------------------------------------------------------------
> #if(${deploy.domain}=='testString')
> <bean class="MY_CLASS1">
> <property name="MY_PROPERTY_NAME1">
> <value>aaa</value>
> </property>
> </bean>
> #end
> <bean class="MY_CLASS2">
> <property name="MY_PROPERTY_NAME2">
> <value>${provider.version}</value>
> </property>
> </bean>
> ----------------------------------------------
> My got the output in fact:
> ----------------------------------------------
> <bean class="MY_CLASS2">
> <property name="MY_PROPERTY_NAME2">
> <value>1.0.0</value>
> </property>
> </bean>
> ----------------------------------------------
> My expected output:
> ----------------------------------------------
> <bean class="MY_CLASS1">
> <property name="MY_PROPERTY1">
> <value>aaa</value>
> </property>
> </bean>
> <bean class="MY_CLASS2">
> <property name="MY_PROPERTY_NAME2">
> <value>1.0.0</value>
> </property>
> </bean>
> ----------------------------------------------
> My suggestion to fix this bug:
> ASTReference.java
> ----------------------------------------------
> The method before change:
> public Object value(InternalContextAdapter context)
> throws MethodInvocationException
> {
> return (computableReference ? execute(null, context) : null);
> }
> After change:
> public Object value(InternalContextAdapter context)
> throws MethodInvocationException
> {
> Object value = this.computableReference?this.execute((Object)null,
> context):null;
> if(value == null && !this.escaped) {
> // process the value by EventHandlerUtil
> value = EventHandlerUtil.referenceInsert(this.rsvc, context,
> this.literal, value);
> }
> return value;
> }
> ----------------------------------------------
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