springframework-developer

[Springframework-developer] Confusing NotWritablePropertyException for invalid bean property

[Jeremy H. <jh...@fa...>]

I have had an issue where a spring configured property is "set" with a
more specific type than the getter-method returns.  The reason is that
the getter method implements an interface and is required to return a
specific type.  The net result is that the getter and setter method take
in/return different class types.  My getter and setter looked like the
code below:

    public Component getView() {
        return view;
    }


    public void setView( Container view ) {
        this.view = view;
    }


This is probably not legal, JavaBeans style access, and my solution
ended up being renaming the method in the interface.  However, the error
message I received was confusing at best, since the property "view" is
obviously writeable based on the code pasted above.  The error message
was:

org.springframework.beans.factory.BeanCreationException: Error creating
bean with name 'alarmBanner' defined in class path resource
[default.dynapp.spring.xml]: Error setting property values; nested
exception is org.springframework.beans.NotWritablePropertyException:
Invalid property 'view' of bean class [AlarmBannerController]: Property
'view' is not writable
org.springframework.beans.NotWritablePropertyException: Invalid property
'view' of bean class [AlarmBannerController]: Property 'view' is not
writable
	at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:666)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:588)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:720)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValues(BeanWrapperImpl.java:747)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValues(BeanWrapperImpl.java:736)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:797)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:637)

The getter was not even required for spring, as I only set this
property.

I have two questions:
1) Is this behavior desirable?  Should Spring throw an exception if the
getter and setter's class type does not match.  This is probably not
really valid JavaBean-style properties, but obviously you can still get
and set the "view" property.  In my case, I was not even "getting" the
property using spring, but only setting it.

2) If this is the desired behavior, should the error message displayed
be clearer?  I have seen this error in the past and it usually means
that there is no setter method or the setter method had non-public
access.  It seems like this error message should read more like
"Property 'view' is not a valid bean property."  - or something like
that.


Jeremy Haile

[Springframework-developer] NotWritablePropertyException encountered while deploying the war file

[Lynette K. <kn...@si...>]

Jeremy Haile <jhaile <at> fastmail.fm> writes:

> 
> I have had an issue where a spring configured property is "set" with a
> more specific type than the getter-method returns.  The reason is that
> the getter method implements an interface and is required to return a
> specific type.  The net result is that the getter and setter method take
> in/return different class types.  My getter and setter looked like the
> code below:
> 
>     public Component getView() {
>         return view;
>     }
> 
>     public void setView( Container view ) {
>         this.view = view;
>     }
> 
> This is probably not legal, JavaBeans style access, and my solution
> ended up being renaming the method in the interface.  However, the error
> message I received was confusing at best, since the property "view" is
> obviously writeable based on the code pasted above.  The error message
> was:
> 
> org.springframework.beans.factory.BeanCreationException: Error creating
> bean with name 'alarmBanner' defined in class path resource
> [default.dynapp.spring.xml]: Error setting property values; nested
> exception is org.springframework.beans.NotWritablePropertyException:
> Invalid property 'view' of bean class [AlarmBannerController]: Property
> 'view' is not writable
> org.springframework.beans.NotWritablePropertyException: Invalid property
> 'view' of bean class [AlarmBannerController]: Property 'view' is not
> writable
> 	at org.springframework.beans.BeanWrapperImpl.setPropertyValue
(BeanWrapperImpl.java:666)
> 	at org.springframework.beans.BeanWrapperImpl.setPropertyValue
(BeanWrapperImpl.java:588)
> 	at org.springframework.beans.BeanWrapperImpl.setPropertyValue
(BeanWrapperImpl.java:720)
> 	at org.springframework.beans.BeanWrapperImpl.setPropertyValues
(BeanWrapperImpl.java:747)
> 	at org.springframework.beans.BeanWrapperImpl.setPropertyValues
(BeanWrapperImpl.java:736)
> 	at 
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.ap
plyPropertyValues(AbstractAutowireCapableBeanFactory.java:797)
> 	at 
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.po
pulateBean(AbstractAutowireCapableBeanFactory.java:637)
> 
> The getter was not even required for spring, as I only set this
> property.
> 
> I have two questions:
> 1) Is this behavior desirable?  Should Spring throw an exception if the
> getter and setter's class type does not match.  This is probably not
> really valid JavaBean-style properties, but obviously you can still get
> and set the "view" property.  In my case, I was not even "getting" the
> property using spring, but only setting it.
> 
> 2) If this is the desired behavior, should the error message displayed
> be clearer?  I have seen this error in the past and it usually means
> that there is no setter method or the setter method had non-public
> access.  It seems like this error message should read more like
> "Property 'view' is not a valid bean property."  - or something like
> that.
> 
> Jeremy Haile
> 
> 
> -------------------------------------------------------
> SF email is sponsored by - The IT Product Guide
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> 

I'm also hitting the same error.

<Dec 21, 2004 2:24:51 PM GMT+08:00> <Error> <HTTP> <BEA-101216> 
<Servlet: "context" failed to preload on startup in Web application: "Crips".
javax.servlet.ServletException: Error creating bean with name 'exam' defined 
in ServletContext resource [/WEB-INF/applicationContext.xml]: Error setting 
property values; nested exception is 
org.springframework.beans.NotWritablePropertyException: Invalid 
property 'marksDAO' of bean class [school.eng.electronics.business.ExamImpl]: 
Property 'marksDAO' is not writable
        at weblogic.servlet.internal.ServletStubImpl.createServlet
(ServletStubImpl.java:884)
        at weblogic.servlet.internal.ServletStubImpl.createInstances
(ServletStubImpl.java:848)
        at weblogic.servlet.internal.ServletStubImpl.prepareServlet
(ServletStubImpl.java:787)
        at weblogic.servlet.internal.WebAppServletContext.preloadServlet
(WebAppServletContext.java:3252)
        at weblogic.servlet.internal.WebAppServletContext.preloadServlets
(WebAppServletContext.java:3209)
        at weblogic.servlet.internal.WebAppServletContext.preloadServlets
(WebAppServletContext.java:3195)
        at weblogic.servlet.internal.WebAppServletContext.preloadResources
(WebAppServletContext.java:3174)
        at weblogic.servlet.internal.WebAppServletContext.setStarted
(WebAppServletContext.java:5647)
        at weblogic.servlet.internal.WebAppModule.start(WebAppModule.java:869)
        at weblogic.j2ee.J2EEApplicationContainer.start
(J2EEApplicationContainer.java:2022)
        at weblogic.j2ee.J2EEApplicationContainer.activate
(J2EEApplicationContainer.java:2063)
        at 
weblogic.management.deploy.slave.SlaveDeployer$ComponentActivateTask.activateCo
ntainer(SlaveDeployer.java:2592)
        at weblogic.management.deploy.slave.SlaveDeployer$ActivateTask.doCommit
(SlaveDeployer.java:2515)
        at weblogic.management.deploy.slave.SlaveDeployer$Task.commit
(SlaveDeployer.java:2317)
        at weblogic.management.deploy.slave.SlaveDeployer$Task.checkAutoCommit
(SlaveDeployer.java:2399)
        at weblogic.management.deploy.slave.SlaveDeployer$Task.prepare
(SlaveDeployer.java:2311)
        at weblogic.management.deploy.slave.SlaveDeployer$ActivateTask.prepare
(SlaveDeployer.java:2479)
        at weblogic.management.deploy.slave.SlaveDeployer.processPrepareTask
(SlaveDeployer.java:798)
        at weblogic.management.deploy.slave.SlaveDeployer.prepareDelta
(SlaveDeployer.java:507)
        at weblogic.management.deploy.slave.SlaveDeployer.prepareUpdate
(SlaveDeployer.java:465)
        at weblogic.drs.internal.SlaveCallbackHandler$1.execute
(SlaveCallbackHandler.java:25)
        at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
        at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)
>

As stated in Spring documentation, the getter method is not required for 
spring, and I only set this property.
I did not hit the NotWritablePropertyException with only 1 DAO, ie. if I only 
have MarksDAO in ExamImpl, I do not have such an exception.

[ExamImpl.java]

private MarksDAO marksDAO;
private SADAO saDAO;

  public void setMarksDAO(MarksDAO marksDAO) {
    this.marksDAO = marksDAO;
  }

  public void setSADAO(SADAO saDAO) {
    this.saDAO = saDAO;
  }

....

[applicationContext.xml]

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD 
BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
  <bean id="exam" class="school.eng.electronics.business.ExamImpl">
    <property name="marksDAO"><ref bean="marksDAO"/></property>
    <property name="saDAO"><ref bean="saDAO"/></property>
  </bean>

  <bean id="marksDAO" class="school.eng.electronics.dao.TestMarksDAO"/>
  <bean id="saDAO" class="school.eng.electronics.dao.TestSADAO"/>

</beans>

[MarksDAO.java]
public interface MarksDAO {
...
}

[TestMarksDAO.java]
public class TestMarksDAO implements MarksDAO {
...
}

As mentioned above, as spring does not require a getter method and I do not 
have a getter method, why do I have such an exception thrown when I try to 
deploy my war file??

Thank you.