[Springframework-developer] Wiring VelocityEngine with a DataSourceResourceLoader

[Matt R. <li...@ra...>]

I've been talking with some Velocity folks about modifying their  
DataSourceResourceLoader to allow setting the DataSource (currently it  
makes you specify a JNDI string in your properties).  They have done  
this and provided a patch:

http://issues.apache.org/bugzilla/show_bug.cgi?id=28611

This is my idea of how it would be configured in Spring:

<!-- Configure Velocity for sending e-mail -->
<bean id="velocityEngine"  
class="org.springframework.ui.velocity.VelocityEngineFactoryBean"  
singleton="true">
     <property name="velocityProperties">
         <props>
             <prop key="resource.loader">ds</prop>
             <prop  
key="ds.resource.loader.resource.table">template</prop>
             <prop  
key="ds.resource.loader.resource.keycolumn">name</prop>
             <prop  
key="ds.resource.loader.resource.templatecolumn">content</prop>
             <prop  
key="ds.resource.loader.resource.timestampcolumn">last_modified</prop>
         </props>
     </property>
     <property name="resourceLoader"><ref  
local="templateLoader"/></property>
</bean>

<bean id="templateLoader" singleton="true"
      
class="org.apache.velocity.runtime.resource.loader.DataSourceResourceLoa 
der">
     <property name="dataSource"><ref local="dataSource"/></property>
</bean>

However, I get the following error:

     [junit] Caused by:  
org.springframework.beans.factory.BeanCreationException: Error creating  
bean with name 'velocityEngine' defined in class path resource  
[applicationContext.xml]: Error setting property values; nested  
exception is  
org.springframework.beans.PropertyAccessExceptionsException:  
PropertyAccessExceptionsException (1 errors); nested  
propertyAccessExceptions are:  
[org.springframework.beans.TypeMismatchException: Failed to convert  
property value of type  
[org.apache.velocity.runtime.resource.loader.DataSourceResourceLoader]  
to required type [org.springframework.core.io.ResourceLoader] for  
property 'resourceLoader'; nested exception is  
java.lang.IllegalArgumentException: argument type mismatch]

Is it possible to allow this, or some other way of initializing this  
ResourceLoader and putting it in the Engine?  Here's the code you can  
use if you were programming this:

  DataSourceResourceLoader ds = new DataSourceResourceLoader();
  ds.setDataSource(DATASOURCE);
  Velocity.setProperty("ds.resource.loader.instance",ds);
  Velocity.init();

Thanks,

Matt