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  1. Camel
  2. CAMEL-10548

Converter from List to String is not found when @EnableAutoConfiguration is used

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 2.18.2, 2.19.0
    • Component/s: camel-spring-boot
    • Labels:
      None
    • Estimated Complexity:
      Unknown

      Description

      This very simple spring-boot application :

      @SpringBootApplication
      public class Application {
          public static void main(String[] args) {
              SpringApplication.run(Application.class, args);
          }
      
          @Component
          public class MyRouteBuilder extends RouteBuilder {
              @Override
              public void configure() throws Exception {
                  from("timer:person")
                      .setBody().constant(Arrays.asList(
                          new Person("Peter", 25),
                          new Person("John", 33)
                      ))
                      .log("Body is ${body}");
              }
          }
      
          public static class Person {
              private String name;
              private int age;
      
              public Person(String name, int age) {
                  this.name = name;
                  this.age = age;
              }
      
              public String getName() {
                  return name;
              }
      
              public void setName(String name) {
                  this.name = name;
              }
      
              public int getAge() {
                  return age;
              }
      
              public void setAge(int age) {
                  this.age = age;
              }
      
              @Override
              public String toString() {
                  return "Person{" +
                      "name='" + name + '\'' +
                      ", age=" + age +
                      '}';
              }
          }
      }
      

      Fails to resolve the simple expression ${body} because of the following exception:

      org.apache.camel.TypeConversionException: Error during type conversion from type: java.lang.String to the required type: java.lang.String with value [Person{name='Peter', age=25}, Person{name='John', age=33}] due Failed to convert from type [java.util.Arrays$ArrayList<?>] to type [java.lang.String] for value '[Person{name='Peter', age=25}, Person{name='John', age=33}]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.util.Arrays$ArrayList<?>] to type [java.lang.String]
      	at org.apache.camel.impl.converter.BaseTypeConverterRegistry.createTypeConversionException(BaseTypeConverterRegistry.java:629) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:150) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.support.ExpressionAdapter.evaluate(ExpressionAdapter.java:41) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.builder.ExpressionBuilder$75.evaluate(ExpressionBuilder.java:1795) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.support.ExpressionAdapter.evaluate(ExpressionAdapter.java:36) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.processor.LogProcessor.process(LogProcessor.java:53) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:542) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:197) [camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.processor.Pipeline.process(Pipeline.java:120) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.processor.Pipeline.process(Pipeline.java:83) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:197) [camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(TimerConsumer.java:192) [camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.java:76) [camel-core-2.18.0.jar:2.18.0]
      	at java.util.TimerThread.mainLoop(Timer.java:555) [na:1.8.0_112]
      	at java.util.TimerThread.run(Timer.java:505) [na:1.8.0_112]
      Caused by: org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.util.Arrays$ArrayList<?>] to type [java.lang.String] for value '[Person{name='Peter', age=25}, Person{name='John', age=33}]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.util.Arrays$ArrayList<?>] to type [java.lang.String]
      	at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:42) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:192) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:176) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	at org.apache.camel.spring.boot.SpringTypeConverter.convertTo(SpringTypeConverter.java:46) ~[camel-spring-boot-2.18.0.jar:2.18.0]
      	at org.apache.camel.impl.converter.BaseTypeConverterRegistry.doConvertTo(BaseTypeConverterRegistry.java:346) ~[camel-core-2.18.0.jar:2.18.0]
      	at org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:133) ~[camel-core-2.18.0.jar:2.18.0]
      	... 14 common frames omitted
      Caused by: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.util.Arrays$ArrayList<?>] to type [java.lang.String]
      	at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:313) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:195) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	at org.springframework.core.convert.support.CollectionToStringConverter.convert(CollectionToStringConverter.java:68) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:36) ~[spring-core-4.3.3.RELEASE.jar:4.3.3.RELEASE]
      	... 19 common frames omitted
      

      The root cause is spring failing to find a converter for Person --> String and as the SpringTypeConverter registered by camel-spring-boot is one of the fallback converters used by BaseTypeConverterRegistry, it leads Camel to fail too.

      As today is a Camel TypeConverter fails with an exception while looping over fallback converters, the loops ends and the conversion fails too. It may turn out that the bug is caused by the way camel uses Spring's type converters but it may be good to catch exceptions and try the next converter, Claus Ibsen make sense ?

      A workaround is to create a custom converter for the class:

          @Component
          public class PersonConverter implements Converter<Person, String> {
              @Override
              public String convert(Person source) {
                  return source.toString();
              }
          }
      

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              • Assignee:
                lb Luca Burgazzoli
                Reporter:
                lb Luca Burgazzoli
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                Dates

                • Created:
                  Updated:
                  Resolved: