Passing parameter value from one bean to another

[socram]

I've the following beans:

	<bean 
		id="pippoBean"
		class="test.Pippo">
		
		<property name="codice" value="ABCD">
		<property name="pluto" ref="plutoBean">
		
	</bean>
	
	<bean 
		id="plutoBean"
		class="test.Pluto">
		
		<property name="codice">
			<bean 	id="pippoBean.codice" 
				class="org.springframework.beans.factory.config.PropertyPathFactoryBean"/>
		</property>
		
	</bean>

The above doesn't work because:
- pippoBean has a reference to plutoBean
- plutoBean requires a property from pippoBean during initialization

Is there an "elegant way" to pass the value of "codice" property from pippoBean to plutoBean.

Thank you in advance

[Costin Leau]

The beans are dependent one each other so there the solution depends on each case. In most cases the logic is distributed across the two beans and it could be simply put in another bean. Another solution is to initialize the property inside your plutoBean (you have the reference to pippioBean and just call getCodice).
One solution a bit more complex is to add a postProcessor that will do the initialization after all the beans have been initialized.

[Andrew Swan]

Could you have a third bean (with no dependencies on the other two) whose only purpose is to store the value of the "codice" property? Then the other two beans could refer to it and you wouldn't be duplicating the actual value anywhere. For example:

<bean id="codice" class="java.lang.String">
  <constructor-arg type="java.lang.String" value="ABCD"/>
</bean>

<bean id="pippoBean" class="test.Pippo">
  <property name="codice">
    <bean id="codice.toString"
      class="org.springframework.beans.factory.config.PropertyPathFactoryBean"/>
  </property>
  <property name="pluto" ref="plutoBean">
</bean>
    
<bean id="plutoBean" class="test.Pluto">
  <property name="codice">
    <bean id="codice.toString"
      class="org.springframework.beans.factory.config.PropertyPathFactoryBean"/>
  </property>
</bean>

I haven't tested this. Or possibly a better idea is to read the "codice" value from a property file?

Andrew

[socram]

Unfortunately the above does not work, because the bean

<property name="codice">
  <bean 
    id="codice.toString"
    class="org.springframework.beans.factory.config.PropertyPathFactoryBean"/>
</property>

would cause the PropertyPathFactoryBean to call a getter for the property "toString", that is "getToString", which does not exists in java.lang.toString.

I've found a nice-enough solution using the PropertyPlaceholderConfigurer, and setting the value of the shared property in an external properties file:

<bean
  id="PropertyRegistry"
  class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
  <property name="location" value="somewhere/in/classpath/registry.properties"/>
</bean>

<bean 
  id="pippoBean"
  class="test.Pippo">
  
  <property name="codice">
    <value>${prop.codice}</value>
  </property>
  <property name="pluto" ref="plutoBean">
</bean>
  
<bean 
  id="plutoBean"
  class="test.Pluto">
  
  <property name="codice">
    <value>${prop.codice}</value>
  </property>
</bean>

where prop.codice is defined in "somewhere/in/classpath/registry.properties".

This works for me, because it allows me to share properties' values among beans.
Any comment is welcome.