Custom generic converter not found: no matching editors or conversion strategy found

[j.gohel]

I have created a StringToMapConverter for converting string in predefined format to a Map of key-value pairs.The key can be Enum type also.

However in the converter I required the reference to org.springframework.core.convert.ConversionService instance for converting string to enum.Thus in my myapp-servlet.xml context I tried registering like:

<bean id="stringToMapConverter" class="com.myapp.util.StringToMapConverter"/>

<bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean">
	        <property name="converters">
	            <bean ref="stringToMapConverter" />
	        </property>
</bean>

This ended me up in circular dependency error like "conversionService: FactoryBean which is currently in creation returned null from getObject".

Thus I tried using a class ConverterConfig annotated with @Configuration (code I have provided below) which resolved this circular dependency error but now I am facing the following error.

org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 1 errors
Field error in object 'searchResultsRefiner' on field 'filtersMap': rejected value []; codes [typeMismatch.searchResultsRefiner.filtersMap,typeMismatch.filtersMap,typeMismatch.java.util.Map,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [searchResultsRefiner.filtersMap,filtersMap]; arguments []; default message [filtersMap]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'java.util.Map' for property 'filtersMap'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [java.util.Map] for property 'filtersMap': no matching editors or conversion strategy found]
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:810)
    at or

I debugged my application and found that the converter was successfully getting added to the registery.But still the framework is unable to find it at time when data is required to convert from java.lang.String to java.util.Map.

Below mentioned is the code I have written:

SearchResultsRefiner.java

 public class SearchResultsRefiner {
       
        private Map<SearchRefineFilter, String> filtersMap;

        public SearchResultsRefiner() {}
        

        public Map<SearchRefineFilter, String> getFiltersMap() {
            return filtersMap;
        }

        public void setFiltersMap(Map<SearchRefineFilter, String> filtersMap) {
            this.filtersMap = filtersMap;
        }

    }

ConverterConfig.java

  import java.util.Collections;

    @Configuration
    public class ConverterConfig {
        
        private ConversionService conversionService;
        private ConverterRegistry converterRegistry;

        @Bean
        public ConversionService conversionService() {
            this.conversionService = ConversionServiceFactory.createDefaultConversionService();
            this.converterRegistry = (GenericConversionService) this.conversionService;
            return conversionService;
        }
        
        
        @Bean
        @DependsOn(value="conversionService")
        public StringToMapConverter stringToMapConverter() {
            StringToMapConverter stringToMapConverter = new StringToMapConverter();
            stringToMapConverter.setConversionService(this.conversionService);
            
            ConversionServiceFactory.registerConverters(
                    Collections.singleton(stringToMapConverter), this.converterRegistry);
            
            return stringToMapConverter;
        }
    }

Server startup log

 2012-01-19 20:37:08,108 INFO   [ContextLoader] Root WebApplicationContext: initialization started 
    2012-01-19 20:37:08,142 INFO   [XmlWebApplicationContext] Refreshing Root WebApplicationContext: startup date [Thu Jan 19 20:37:08 IST 2012]; root of context hierarchy 
    2012-01-19 20:37:08,201 INFO   [XmlBeanDefinitionReader] Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/util-context.xml] 
    2012-01-19 20:37:08,342 INFO   [XmlBeanDefinitionReader] Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/service-context.xml] 
    2012-01-19 20:37:08,677 INFO   [XmlBeanDefinitionReader] Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/persistence-context.xml] 
    2012-01-19 20:37:09,215 INFO   [PropertyPlaceholderConfigurer] Loading properties file from class path resource [fn-cars-bundle.properties] 
    2012-01-19 20:37:09,221 INFO   [PropertyPlaceholderConfigurer] Loading properties file from class path resource [fn-cars-bundle.properties] 
    2012-01-19 20:37:09,233 INFO   [DwrAnnotationPostProcessor] Detected candidate bean [asynchronousRequestHandlerServiceImpl]. Remoting using AsyncService 
    2012-01-19 20:37:09,246 INFO   [DwrAnnotationPostProcessor] Could not infer class for [conversionService]. Is it a factory bean? Omitting bean from annotation processing 
    2012-01-19 20:37:09,246 INFO   [DwrAnnotationPostProcessor] Could not infer class for [stringToMapConverter]. Is it a factory bean? Omitting bean from annotation processing 
    2012-01-19 20:37:09,436 INFO   [DefaultListableBeanFactory] Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@aae8a: defining beans [org.springframework.beans.factory.config.PropertyPlaceholderConfigurer#0,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,messageSource,memcachedClient,velocityEngine,smtpAuthenticator,mailSession,mailSender,converterConfig,resourceBundleUtil,dwrAnnotationPostProcessor,org.springframework.beans.factory.config.PropertyPlaceholderConfigurer#1,locationDAO,,dataSource,sessionFactory,txManager,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,conversionService,stringToMapConverter,__AsyncService,__dwrConfiguration]; root of factory hierarchy

StringToMapConverter

     public class StringToMapConverter implements ConditionalGenericConverter {

        private static final String COMMA = ",";
        private static final String COLON = ":";
        
        private ConversionService conversionService;
        
        /**
         * @param conversionService the conversionService to set
         */
        public void setConversionService(ConversionService conversionService) {
            this.conversionService = conversionService;
        }

        @Override
        public Set<ConvertiblePair> getConvertibleTypes() {
            return Collections.singleton(new ConvertiblePair(String.class, Map.class));
        }
        
        @Override
        public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
            boolean matches = 
                    this.conversionService.canConvert(sourceType, targetType.getMapKeyTypeDescriptor())
                     && this.conversionService.canConvert(sourceType, targetType.getMapValueTypeDescriptor());
            return matches;
        }

        @SuppressWarnings("unchecked")
        @Override
        public Object convert(Object source, TypeDescriptor sourceType,
                TypeDescriptor targetType) {
            
            if (source == null) {
                return null;
            }
            
            String sourceString = (String) source;
            
            if (sourceString.trim().isEmpty()) {
                return Collections.emptyMap();
            }

            @SuppressWarnings("rawtypes")
            Map targetMap = new HashMap();
            

            String[] keyValuePairs = sourceString.split(COMMA);
            String[] keyValueArr = null;
            String key = null;
            String value = null;
            for (String keyValuePair : keyValuePairs) {
                keyValueArr = keyValuePair.split(COLON);
                key = keyValueArr[0].trim();
                value = keyValueArr[1].trim();
                
                Object targetKey = 
                        this.conversionService.convert(
                                key, sourceType, targetType.getMapKeyTypeDescriptor(key));
                
                targetMap.put(targetKey, value);
            }       
            
            return targetMap;
        }

    }

Please help in getting this resolved.
Thanks,
Jignesh

[j.gohel]

I have got the issue I posted above resolved and posting my solution here for reference.

Before posting what was causing the error, I would like to show my <servlet-name>-servlet.xml context file loaded by my application's Dispatcher Servlet.

<servlet-name>-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="..."  xsi:schemaLocation="...">

        <context:annotation-config />

        <context:component-scan base-package="<MY-PACKAGES>" />

        <!-- Handles GET requests for /resources/** by efficiently serving static content in the ${webappRoot}/resources dir -->
        <mvc:resources location="/resources/" mapping="/resources/**"/>

        <!--
            This tag registers the HandlerMapping and HandlerAdapter required to dispatch requests to your @Controllers. 
            In addition, it applies sensible defaults based on what is present in your classpath. Such defaults include:

            1) Using the Spring 3 Type ConversionService as a simpler and more robust alternative to JavaBeans PropertyEditors
            2) Support for formatting Number fields with @NumberFormat
            3) Support for formatting Date, Calendar, and Joda Time fields with @DateTimeFormat, if Joda Time is on the classpath 
            4) Support for validating @Controller inputs with @Valid, if a JSR-303 Provider is on the classpath 
            5) Support for reading and writing XML, if JAXB is on the classpath 
            6) Support for reading and writing JSON, if Jackson is on the classpath   
         -->

        <mvc:annotation-driven/>

        <mvc:interceptors>
          <bean class="org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor">
              <property name="sessionFactory">
                  <ref bean="sessionFactory"/>
              </property>
              <property name="singleSession" value="false" />
          </bean>
        </mvc:interceptors>

        <!-- 
             Without the following adapter, we'll get a "Does your handler implement a supported interface like Controller?"
             This is because mvc:annotation-driven element doesn't declare a SimpleControllerHandlerAdapter
             For more info
             See http://stackoverflow.com/questions/3896013/no-adapter-for-handler-exception
             See http://forum.springsource.org/showthread.php?t=48372&highlight=UrlFilenameViewController    
        -->
        <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />

        <!-- 
              org.springframework.web.servlet.view.ResourceBundleViewResolver
              The bundle is typically defined in a properties file, 
              located in the class path. The default bundle basename is "views". 
        -->
        <bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver">
             <property name="basename" value="views" />
        </bean>

</beans>

As can be seen in above file I have used <mvc:annotation-driven/> which by default activates the org.springframework.format.support.FormattingConve rsionService. I needed an instance of org.springframework.core.convert.support.GenericCo nversionService instead, to which I am registering my custom converter StringToMapConverter (shown in my first post) using ConverterConfig (shown in my first post).

The value of property, at spring container initialization time, org.springframework.web.bind.support.ConfigurableW ebBindingInitializer.setConversionService(Conversi onService) was getting set as the instance of org.springframework.format.support.FormattingConve rsionService instead of org.springframework.core.convert.support.GenericCo nversionService to which i registered my custom converter and thus the error was thrown that no matching editors or conversion strategy found.

However I don't need the formatting conversion service in my application as of now and just wanted to register my custom converter.Thus to achieve my goal I used the updated code shown below:

Updated <servlet-name>-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="..." xsi:schemaLocation="...">

        <context:annotation-config />

        <context:component-scan base-package="<MY-PACKAGES>" />

        <!-- Handles GET requests for /resources/** by efficiently serving static content in the ${webappRoot}/resources dir -->
        <mvc:resources location="/resources/" mapping="/resources/**"/>
       
        <!-- 
              We just require the converter feature not the formatting feature.Thus
              registering only the org.springframework.core.convert.support.GenericConversionService and 
              not org.springframework.format.support.FormattingConversionService which
              <mvc:annotation-driven> activates by default.Also we are registering
              a custom converter using the com.flightnetwork.cars.controller.util.ConverterConfig
              class 
         -->
        <!-- Added this to resolve my issue -->
        <mvc:annotation-driven conversion-service="conversionService"/> 

        <mvc:interceptors>
          <bean class="org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor">
              <property name="sessionFactory">
                  <ref bean="sessionFactory"/>
              </property>
              <property name="singleSession" value="false" />
          </bean>
        </mvc:interceptors>

      
        <bean class="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />


        <bean id="viewResolver" class="org.springframework.web.servlet.view.ResourceBundleViewResolver">
             <property name="basename" value="views" />
        </bean>

        <!-- Added this to resolve my issue -->
        <bean id="conversionService" class="org.springframework.context.support.ConversionServiceFactoryBean"/>
</beans>

Updated ConverterConfig.java

 import java.util.Collections;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.DependsOn;
    import org.springframework.core.convert.ConversionService;
    import org.springframework.core.convert.converter.ConverterRegistry;
    import org.springframework.core.convert.support.ConversionServiceFactory;

    @Configuration
    public class ConverterConfig {

        @Autowired
        private ConversionService conversionService;

        @Autowired
        private ConverterRegistry converterRegistry;

        @Bean
        @DependsOn(value="conversionService")
        public StringToMapConverter stringToMapConverter() {
            StringToMapConverter stringToMapConverter = new StringToMapConverter();
            stringToMapConverter.setConversionService(this.conversionService);

            ConversionServiceFactory.registerConverters(
                    Collections.singleton(stringToMapConverter), this.converterRegistry);

            return stringToMapConverter;
        }
    }

Thanks,
Jignesh