Error executing FreeMarker template

[P_Giannuzzi]

Hello everyone,

I'm doing some practice with Alfresco 5.2 (Community), to understand its mechanisms.

I'm trying to understand the customizable constraints through Java class, and to do this I followed (slightly adapting it) the example provided at this link  https://hub.alfresco.com/t5/alfresco-content-services-hub/content-model-constraints/ba-p/289687 

But when I open the form the console returns the Error executing FreeMarker template error

What am I doing wrong? I am attaching content model, java class and console log.

CONTENT MODEL

<constraints>
     <constraint name="trbar:FactorsOf" type="com.went.platformsample.Multipli">
         <parameter name="multipleOf"><value>2</value></parameter>
     </constraint>
</constraints>

<property name="trbar:Eta">
	<title>Età</title>
	<description>Età</description>
	<type>d:int</type>
	<mandatory>true</mandatory>
	<index enabled="true">
		<tokenised>true</tokenised>
		<facetable>true</facetable>
	</index>
	<constraints>
		<constraint ref="trbar:FactorsOf" />
	</constraints>
</property>

Multipli.java

package com.went.platformsample;

import java.util.HashMap;
import java.util.Map;

import org.alfresco.service.cmr.dictionary.Constraint;

public class Multipli implements Constraint {
	private Integer multipleOf = 0;

	@Override
	public Map<String, Object> getParameters() {

		System.out.println("getParameters");

		System.out.println("1 valore di multipleOf = " + multipleOf);
		System.out.println("2 valore di multipleOf = " + this.multipleOf);
		Map<String, Object> params = new HashMap<String, Object>(2);

		params.put("multipleOf", this.multipleOf);
		
		System.out.println("3 valore di multipleOf = " + params.get("multipleOf"));
		
		System.out.println("Params = " + params);
		
		return params;
	}

	@Override
	public String getType() {
		System.out.println("getType");
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public String getTitle() {
		System.out.println("getTitle");
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public String getShortName() {
		System.out.println("getShortName");
		// TODO Auto-generated method stub
		return null;
	}

	@Override
	public void initialize() {
		System.out.println("initialize");
		// TODO Auto-generated method stub

	}

	@Override
	public void evaluate(Object value) {
		System.out.println("evaluate");
		// TODO Auto-generated method stub

	}

	public Integer getMultipleOf() {
		System.out.println("getMultipleOf " + multipleOf);
		return multipleOf;
	}

	public void setMultipleOf(Integer multipleOf) {
		System.out.println("setMultipleOf " + multipleOf);
		this.multipleOf = multipleOf;
	}

}

Console log

2021-08-20 09:40:21,110  ERROR [freemarker.runtime] [http-bio-8080-exec-13] Error executing FreeMarker template
 FreeMarker template error:
The following has evaluated to null or missing:
==> jsonUtils.encodeJSONString(x)  [in template "org/alfresco/repository/forms/formdefinition.lib.ftl" at line 14, column 15]

Tip: If the failing expression is known to be legally null/missing, either specify a default value with myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthessis: (myOptionVar.foo)!myDefault, (myOptionVar.foo)??

The failing instruction (FTL stack trace):
----------
==> ${cnstrnt.type} auto-escaped  [in template "org/alfresco/repository/forms/formdefinition.lib.ftl" in macro "formDefJSON" at line 45, column 36]
    #if field.dataType??  [in template "org/alfresco/repository/forms/formdefinition.lib.ftl" in macro "formDefJSON" at line 36, column 21]
    @formDefLib.formDefJSON form=form  [in template "org/alfresco/repository/forms/formdefinition.post.json.ftl" at line 2, column 1]
----------

Java stack trace (for programmers):
----------
freemarker.core.InvalidReferenceException: [... Exception message was already printed; see it above ...]
	at freemarker.core.InvalidReferenceException.getInstance(InvalidReferenceException.java:98)
	at freemarker.core.EvalUtil.coerceModelToString(EvalUtil.java:382)
	at freemarker.core.Expression.evalAndCoerceToString(Expression.java:115)
	at freemarker.core.DollarVariable.accept(DollarVariable.java:76)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
	at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:193)
	at freemarker.core.Environment.visitIteratorBlock(Environment.java:509)
	at freemarker.core.IteratorBlock.accept(IteratorBlock.java:103)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
	at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:86)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.IfBlock.accept(IfBlock.java:84)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visitByHiddingParent(Environment.java:286)
	at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:193)
	at freemarker.core.Environment.visitIteratorBlock(Environment.java:509)
	at freemarker.core.IteratorBlock.accept(IteratorBlock.java:103)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.EscapeBlock.accept(EscapeBlock.java:85)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.Macro$Context.runMacro(Macro.java:209)
	at freemarker.core.Environment.visit(Environment.java:694)
	at freemarker.core.UnifiedCall.accept(UnifiedCall.java:116)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.MixedContent.accept(MixedContent.java:93)
	at freemarker.core.Environment.visit(Environment.java:265)
	at freemarker.core.Environment.process(Environment.java:243)
	at org.alfresco.repo.template.FreeMarkerProcessor.process(FreeMarkerProcessor.java:230)
	at org.springframework.extensions.webscripts.AbstractWebScript.renderTemplate(AbstractWebScript.java:967)
	at org.springframework.extensions.webscripts.DeclarativeWebScript.renderFormatTemplate(DeclarativeWebScript.java:267)
	at org.springframework.extensions.webscripts.DeclarativeWebScript.execute(DeclarativeWebScript.java:147)
	at org.alfresco.repo.web.scripts.RepositoryContainer$3.execute(RepositoryContainer.java:512)
	at org.alfresco.repo.transaction.RetryingTransactionHelper.doInTransaction(RetryingTransactionHelper.java:464)
	at org.alfresco.repo.web.scripts.RepositoryContainer.transactionedExecute(RepositoryContainer.java:587)
	at org.alfresco.repo.web.scripts.RepositoryContainer.transactionedExecuteAs(RepositoryContainer.java:656)
	at org.alfresco.repo.web.scripts.RepositoryContainer.executeScriptInternal(RepositoryContainer.java:428)
	at org.alfresco.repo.web.scripts.RepositoryContainer.executeScript(RepositoryContainer.java:308)
	at org.springframework.extensions.webscripts.AbstractRuntime.executeScript(AbstractRuntime.java:399)
	at org.springframework.extensions.webscripts.AbstractRuntime.executeScript(AbstractRuntime.java:210)
	at org.springframework.extensions.webscripts.servlet.WebScriptServlet.service(WebScriptServlet.java:132)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.alfresco.web.app.servlet.GlobalLocalizationFilter.doFilter(GlobalLocalizationFilter.java:68)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
2021-08-20 09:40:21,125  ERROR [extensions.webscripts.AbstractRuntime] [http-bio-8080-exec-13] Exception from executeScript: 07200002 Wrapped Exception (with status template): 07200019 Errore durante l'elaborazione del modello 'The following has evaluated to null or missing:
==> jsonUtils.encodeJSONString(x)  [in template "org/alfresco/repository/forms/formdefinition.lib.ftl" at line 14, column 15]

The impression is that the error is generated when the "return params;" at the end of the Map method.

Thanks in advance for the help.

[cristinamr]

It's failling the view because the value is missing or null. How are you getting and displaying those values?

[P_Giannuzzi]

I had thought of this too, and in fact I put some logs on the console, and the log I print just before "return params;" shows the content of the object correctly valued.

The impression is that something is missing, but I can't understand what.

[cristinamr]

Please share with us your code or what results are you expecting.

When you add a contraint in a model you need to manage the view too. Usually, it's defined under share-config-custom.xml (to display under Share UI). Did you develop this part?

More info here and here.

[P_Giannuzzi]

The view part I have already developed and, before I added this constraint to the content-model, it worked perfectly.

Furthermore, the guide I found from which I tried to generate the constraint does not say in any way (nor have I found other references) of the views.

But as I said, I am convinced that something is missing but I don't understand what.

[cristinamr]

Share with us the view part 🙂

[P_Giannuzzi]

This is the part affected by the constraint, which worked correctly before I applied it.

In addition, I have also defined the other evaluator.

<config condition="trbar:IusPrimeNoctis" evaluator="model-type">
		<forms>
			<form>
				<field-visibility>
					<show id="trbar:Eta" />
				</field-visibility>
				<appearance>
					<set appearance="whitespace" id="trbar:IusPrimeNoctis_cmm_set0" />
					<field id="trbar:Eta" set="trbar:IusPrimeNoctis_cmm_set0"></field>

				</appearance>
			</form>
			
		</forms>
	</config>