[jira] Commented: (VELOCITY-267) Create a DataSourceResourceLoader that can be wired to the datasource with IoC

["Vladimir Terzic (JIRA)" <ji...@apache.org>]

    [ http://issues.apache.org/jira/browse/VELOCITY-267?page=comments#action_12331618 ] 

Vladimir Terzic commented on VELOCITY-267:
------------------------------------------

Velocity requires JNDI context to get DataSource (note check for ctx).
Above enhancement requsted by Matt Raible enables Spring configuration of Velocity JDBC DataSourceLoader which means that now you can pass JDBC DataSource to Velocity using spring config file(via IOC setter injection).

If you are using Spring framework to pass in the DataSource, Velocity does not need to check for the dataSource (and more importantly for context) since it already has reference to it . My suggested enhancement will allow you to run this configuration of Velocity outside of the J2EE environment.

I know...clear as mud ;-)

current code:
--------------------------------------------------------------
private Connection openDbConnection() throws Exception {
  if (ctx == null) {
     ctx = new InitialContext();
  }

  if (dataSource == null) {
     dataSource = (DataSource)ctx.lookup(dataSourceName);
  }

  return dataSource.getConnection();
} 

proposed code:
--------------------------------------------------------------
private Connection openDbConnection() throws Exception {
  if (dataSource != null)
     return dataSource.getConnection();

  if (ctx == null) {
     ctx = new InitialContext();
  }

  if (dataSource == null) {
     dataSource = (DataSource)ctx.lookup(dataSourceName);
  }

  return dataSource.getConnection();
} 

> Create a DataSourceResourceLoader that can be wired to the datasource with IoC
> ------------------------------------------------------------------------------
>
>          Key: VELOCITY-267
>          URL: http://issues.apache.org/jira/browse/VELOCITY-267
>      Project: Velocity
>         Type: Improvement
>   Components: Source
>     Versions: 1.5
>  Environment: Operating System: other
> Platform: Other
>     Reporter: Matt Raible
>     Priority: Minor
>  Attachments: DatabaseResourceLoader.java, resource_ioc.patch, resourceinstance.zip
>
> I'd like to create a ResourceLoader similar to DataSourceResourceLoader, except that I'd like to set 
> the DataSource via IoC (in Spring).  The main reason for this is so my database-loading of templates 
> does not depend on a JNDI connection.  
> The main problem is how to manage a ResourceLoader with Spring and then set it declaratively on its 
> VelocityEngine - rather than via properties.
> <suggested patch from Will Glass-Husain>
> Does this mean that you'd need to pass in an instance of a resource manager
> (initialized with the datasource) to VelocityEngine, rather than just set
> the class name as a property? (MR - Yes)
> As I understand the source code, this doesn't seem possible.  But I think a
> patch wouldn't be difficult.  (a change to
> RuntimeInstance.initializeResourceManager) to look for an instance of the
> class as well as the class name.  Something similar to
> LogManager.createLogSystem which accepts as a property the class name of a
> class that implements LogSystem, or an instance of the class itself.
> </suggested patch>

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