Error on boolean constructor argument

[paul]

Here's a strange error I got during context initialization on a CustomDateEditor bean.

<bean id="customDateEditor" class="org.springframework.beans.propertyeditors.CustomDateEditor">
   <constructor-arg><ref local="dateFormatSql"/></constructor-arg>
   <constructor-arg><value>true</value></constructor-arg>
</bean>

The error I got is with the second contructor argument:

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'customDateEditor' defined in resource [/WEB-INF/applicationContext.xml] of ServletContext: Unsatisfied dependency expressed through constructor argument with index 1 of type [boolean]: Did you specify the correct bean references as generic constructor arguments?

Well I did specify the correct constructor arguments right?

[katentim]

Can you post the code for the referenced bean, id="dateFormatSql"?

[paul]

Here the definition of the referenced bean.

<bean id="dateFormatSql" class="java.text.SimpleDateFormat">
   <constructor-arg><value>yyyy-MM-dd</value></constructor-arg>
</bean>

This should be ok right? Note that the error reports the constructor arg with index 1 (the second) to be the problem.

What am I missing here?

[paul]

It's getting really confusing; I've created a test class with a constructor with a single primitive boolean argument, defined in the bean container as this:

<bean id="testBean" class="nl.ctb.ewub.business.TestClass">
   <constructor-arg><value>true</value></constructor-arg>
</bean>

and it doesn't work as well! Did I misunderstand Spring being able to convert all primitives? How should this be done then? Well, I'm confused. Guys?

[Alef Arendsen]

I suggest you start using indexed constructor arguments. The support for detecting the argument types has it quirks sometimes.

<constructor-arg index="1"><ref bean="dateFormat"/></constructor-arg>
<constructor-arg index="2"><value>true</value></constructor-arg>

I think the index is one-based, but just try it out to be sure.

Hope this helps.

Alef

[paul]

Thank you Alef!

That appears to solve the issue. The bean container initializes without errors when specifying a 0-based index on the <constructor-arg>. Here's the whole solution (for completeness):

<bean id="customDateEditor" class="org.springframework.beans.propertyeditors.CustomDateEditor">
    <constructor-arg index="0"><ref local="dateFormatSql"/></constructor-arg>
    <constructor-arg index="1"><value>true</value></constructor-arg>
</bean>

Guess this is a pitfall for others too, since the error message is a little bit misleading. The error states

Unsatisfied dependency expressed through constructor argument with index 1 of type boolean

. Thus the container correctly recognizes the second boolean argument with index 1. This is a clue that the correspondence between constructor arguments and <constructor-args> element is not ambigious for the container. Nonetheless providing explicit index info solves the issue!

Alef -- thanks again!

[paul]

As a post scriptum: the index attributes on a <constructor-arg> seem to be an undocumented container feature. It appears only in the bean DTD. Shouldn't this be in the section (3.3.1) about type 3 IoC?

[katentim]

the index attributes on a <constructor-arg> seem to be an undocumented

Yes, it probably should be better documented - I'll post a bug (hopefully with doco patch - ). In addition the above values can be resolved by specifying a type. E.g.

<constructor-arg><ref bean="dateFormat"/></constructor-arg>
<constructor-arg type="boolean"><value>true</value></constructor-arg>

I think the index is one-based

It's actually 0 based