Custom Converter Example

[dawez]

This is my full webflow-config.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:webflow="http://www.springframework.org/schema/webflow-config"
       xsi:schemaLocation="
           http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
           http://www.springframework.org/schema/webflow-config
           http://www.springframework.org/schema/webflow-config/spring-webflow-config-2.0.xsd">

   <bean name="/register.htm" id="flowController" class="org.springframework.webflow.mvc.servlet.FlowController">
      <property name="flowExecutor" ref="flowExecutor" />
   </bean>

   <!-- For annotated methods and types -->
   <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
   <bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />

   <!--enable jawr controller to be found without errors-->
   <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />


   <webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry" />

   <!--This creates an XmlFlowRegistryFactory bean -->
   <webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices">
      <webflow:flow-location path="/WEB-INF/flows/register.xml" />
   </webflow:flow-registry>

   <webflow:flow-builder-services id="flowBuilderServices"
                                  view-factory-creator="mvcViewFactoryCreator"
                                  conversion-service="conversionService"
                                  development="true" />

   <bean id="mvcViewFactoryCreator" class="org.springframework.webflow.mvc.builder.MvcViewFactoryCreator">
      <property name="viewResolvers" ref="viewResolver" />
      <property name="useSpringBeanBinding" value="true" />
   </bean>

   <bean class="org.springframework.webflow.mvc.servlet.FlowHandlerMapping">
      <property name="flowRegistry" ref="flowRegistry" />
      <property name="order" value="0" />
   </bean>

   <!-- Enables FlowHandler URL mapping -->
   <bean class="org.springframework.webflow.mvc.servlet.FlowHandlerAdapter">
      <property name="flowExecutor" ref="flowExecutor" />
   </bean>


</beans>

the line webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices" is present so the problem should lie somewhere else. I noticed that the constructor of the ApplicationConversionService is called twice and therefore also the line addConverter("myDate", new MyDateConverter()); inside that class is called twice.

I removed the @Service annotation for this class by using the standard <bean id="" class="" > definition but still the constructor is called twice. Before moving to webflow in my old controller with Spring MVC I was using a property editor for the MyDate class without any isse.

Open for suggestions.

[MartinCz]

Hi.

I swear I tried to solve this problem by searching the forum, but I failed.

The CUSTOM DATE conversion only works one way for me. It only work when the form is submitted (then the date string is properly parsed and converted into java.util.Date). The other way (converting a java.util.Date instance into a formatted String for displaying in a form) does not work.

Neither of this works (java.util.Date is not converted to a formatted String):

<input type="text" class="date_field" value="${ticketFilterCommand.dateFrom}" id="dateFrom" name="dateFrom" />

<form:input path="dateFrom" cssClass="date_field" />

My config:

Spring Framework 2.5.6
Spring Web Flow 2.0.8
com.springsource.org.jboss.el-2.0.0.GA.jar
Tiles 2.0.7

My definitions:

<flow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices">

    <flow:flow-location path="/WEB-INF/flows/tickets_flow.xml" id="auth/tickets" />
    <flow:flow-location path="/WEB-INF/flows/create_ticket_flow.xml" id="auth/create_ticket" />
    <flow:flow-location path="/WEB-INF/flows/ticket_inspector_flow.xml" id="auth/ticket_inspector" />

    <flow:flow-location path="/WEB-INF/flows/contact_persons_flow.xml" id="auth/contact_persons" />
    <flow:flow-location path="/WEB-INF/flows/create_contact_person_flow.xml" id="auth/create_contact_person" />
    <flow:flow-location path="/WEB-INF/flows/edit_contact_person_flow.xml" id="auth/edit_contact_person" />

    <flow:flow-location path="/WEB-INF/flows/contact_person_access_flow.xml" id="auth/contact_person_access" />

</flow:flow-registry>

<flow:flow-executor id="flowExecutor" />

<flow:flow-builder-services id="flowBuilderServices"
    view-factory-creator="mvcViewFactoryCreator"
    conversion-service="myConversionService" />

<bean id="mvcViewFactoryCreator" class="org.springframework.webflow.mvc.builder.MvcViewFactoryCreator">
    <property name="viewResolvers" ref="tilesViewResolver"/>
    <property name="useSpringBeanBinding" value="false" />
</bean>

<bean id="tilesViewResolver" class="org.springframework.js.ajax.AjaxUrlBasedViewResolver">
    <property name="viewClass" value="org.springframework.webflow.mvc.view.FlowAjaxTilesView"/>
</bean>

The custom converter:

public class MyStringToDate extends StringToDate {

    public MyStringToDate() {

        setPattern("dd.MM.yyyy");

    }

}

The custom conversion service with two versions of the addDefaultConverters() method (none of them working):

@Component("myConversionService")
public class MyConversionService extends DefaultConversionService {

    /*@Override
    protected void addDefaultConverters() {

        super.addDefaultConverters();

        addConverter(new MyStringToDate());
        
    }*/

    @Override
    protected void addDefaultConverters() {

        super.addDefaultConverters();

        StringToDate stringToDate = new StringToDate();
        stringToDate.setPattern("dd.MM.yyyy");

        addConverter(stringToDate);

    }

}

Observations:

• I tried to turn the useSpringBeanBinding option on and off without any success or difference.

Question

What am I doing wrong?

Can I use the custom conversion service to convert java.util.Date instances into a formatted string or am I getting something wrong here?

Thank you very much for you assistance and help.

[dawez]

HI MartinCZ,

it seems to me that your converter is a bit too short. I am using the following one. Please try something like this.

public class StringToMyDate extends StringToObject {
   public StringToMyDate() {
      super(MyDate.class);
   }

   @Override
   public Object toObject(String string, Class aClass) throws Exception {
      MyDate myDate = new MyDate(string);
      return myDate;
   }

   @Override
   public String toString(Object object) throws Exception {
      MyDate myDate = (MyDate) object;
      return myDate.toString();
   }

I am converting back<->forth Date class to Mydate class [which contains specific method for my app.] This way is working like a charm.

Let me know if this is not working and I will try to help more.

[MartinCz]

Hi, thanks for the tip. I didn't have to use it though, because my converter suddenly began to work I really have no idea what's going on here, I am pretty sure I didn't do any changes in the code. I was just debugging the framework's code and suddenly it worked.

[dawez]

Hey Cool !

I also had time ago an issue that was working only when debugging in intellij. At the end I managed to understand that the debugger is initializing the classes/object and sometimes you have different results in debug/run configuration.

Cool... working code is always good !

[couchpotato]

Hi guys,

I've been reading this thread back and forth and all info I could find elsewhere about custom converters in Spring. It seems like everyone here has/had similar problems only I can't find a solution for my specific case. I must still be missing something. I get this error:

org.springframework.binding.convert.ConversionExec utorNotFoundException:
Custom ConversionExecutor with id 'userToString' cannot convert from sourceClass [nl.coremail.User] to targetClass [java.lang.String]


My converter userToString is found but spring thinks it can't do the required conversion.

this is my converter:

public class UserToString extends StringToObject {
	
	public UserToString() {
		super(String.class);
	}

	@Override
	public Object toObject(String arg0, Class arg1) throws Exception {
		return new User();
	}

	@Override
	public String toString(Object arg0) throws Exception {
		return "";
	}	   
}

my conversion service:

@Component("webflowConversionService")
public class ApplicationConversionService extends DefaultConversionService {
	
    @Override
    protected void addDefaultConverters() {

        super.addDefaultConverters();
        addConverter("userToString", new UserToString());
    }
}

webflow config contains:

<webflow:flow-builder-services id="flowBuilderServices" conversion-service="webflowConversionService" development="true" />

<webflow:flow-registry id="flowRegistry" base-path="/WEB-INF/flows" flow-builder-services="flowBuilderServices">
<webflow:flow-location-pattern value="/**/*-flow.xml" />
</webflow:flow-registry>

flow contains:

<view-state id="editContact" model="contact">
<binder>
	<binding property="user" converter="userToString" required="true" />			
</binder>
...

jsp contains:

<form:input path="user" />

Can anyone please give me a hand?

Spring 3, also tried 2.5.6.SEC01
Webflow 2.0.8

[couchpotato]

wow, minutes after posting the above I found the problem.

changed:
public UserToString() {
super(String.class);
}

to

public UserToString() {
super(User.class);
}

that was all..

[digz6666]

Following is working for me:

http://forum.springsource.org/showthread.php?p=315661

[gdelprete]

Hi.

I swear I tried to solve this problem by searching the forum, but I failed.

The CUSTOM DATE conversion only works one way for me. It only work when the form is submitted (then the date string is properly parsed and converted into java.util.Date). The other way (converting a java.util.Date instance into a formatted String for displaying in a form) does not work.

I've go exactly the same problem, although the versions I use are different:

Spring Framework 3.0.4
Spring Web Flow 2.2.0
Liferay (this is a portlet)

View technology is plain JSP, using the Spring Form tag library.

The converter I'm trying to use is

StringToDate dateConverter = new StringToDate();
dateConverter.setPattern("dd/MM/yyyy");
addConverter(dateConverter);

Yes, I have the

conversion-service="applicationConversionService"

in my webflow configuration.

If I debug the StringToDate class, I can see the "toObject" method being called on submit, but not the "toString" one on rendering.

Has anyone understood why it works in one direction and not in the other?
Is it perhaps a known bug?

Regards,
Gabriele

[gdelprete]

I answer to myself, as I found the solution.

See also my comment on bug 1056 .

The problem was that in my flow definition, I had the model bean specified as "flowScope.searchModel"; unfortunately, you must not use this notation but only use the bean name ("searchModel"), because SWF does not handle scope specifiers in the model attribute in view-states.