javaspringspring-elspelevaluationexceptionbeancreationexception

Using SpEL to copy references of a beans is not working

I have been experimenting around with Spring. I wish to copy a bean's value and reference properties for another bean by making use of SpEL.

Consider this bean:

<bean id="kenny" class="com.springinaction.springidol.Instrumentalist">
    <property name="song" value="#{'Jingle Bells'}" /> 
    <property name="instrument" ref="piano" /> 
</bean>

I wish to copy its values into another bean, as shown below:

<bean id="carl" class="com.springinaction.springidol.Instrumentalist"> 
    <property name="song" value="#{kenny.song}" /> 
    <property name="instrument" ref="#{kenny.instrument}" /> <-- I GET EXCEPTION OVER HERE

</bean>

However, I get an exception for the second prpoperty as it does not manage to copy kenny's intrument. The song is copied correctly without any exception being thrown

I get this exception:

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'carl' defined in class path resource [Beans.xml]: Cannot resolve reference to bean '#{kenny.instrument}' while setting bean property 'instrument'; nested exception is org.springframework.beans.factory.BeanExpressionException: Expression parsing failed; nested exception is org.springframework.expression.spel.SpelEvaluationException: EL1008E:(pos 6): Field or property 'instrument' cannot be found on object of type 'com.springinaction.springidol.Instrumentalist'

Any idea how I can copy the instrument and set it for the bean with id "carl" please?

Solution

  • A ref is a reference to another bean; in your case you want to use the value of the instrumemt property of the kenny bean.

    You should use

     <property name="instrument" value="#{kenny.instrument}" />

    This assumes there is a getInstrument() method on Instrumentalist.