Dynamic database attribute

[John Armstrong <si...@gmail.com>]

Hello Cayenne people,
  First off, thank god for Cayenne. Its made my life a lot better and
Hibernate is but a nightmare now. Thanks.

Ok so my issue. I have a stand-alone app. In this app it uses the ant
api to create a derby database in the users home directory. Some
snippets:

I config ant as :
		p.setProperty("dbFile", System.getProperty("user.home")
				+ "/portfolioDB");

And then my build.xml says:
<database url="jdbc:derby:${dbFile}"
driverClassName="org.apache.derby.jdbc.EmbeddedDriver" username=""
password="" />

This allows me to inject my ddl into the database on first run and
have the database be localized to the user account across platforms.

I need a way to inject this same ${dbFile} context into the
*Node.driver file so that Cayenne accesses the database I just created
and populated at first run.

Currently mine says:

<url value="jdbc:derby:/portfolioDB;create=true"/>

Which obviously is not dynamic. It would be great if I could set it to
<url value="jdbc:derby:${dbFile};create=true"/>

Is this possible? I am imagining a way to set an environment variable
or some sort of custom config class that sets this. This app is
launched from a webstart so rewriting the config file is not a good
answer for me unless I absolutely have to. That would obviously
require a custom config class of some sort but is a level of
complexity that feels unnecessary.

Thanks, this is a bit into the internals for me and I lose my way quickly.

John-

Re: Dynamic database attribute

[Andrus Adamchik <an...@objectstyle.org>]

Hi John,

Actually a good idea for us to introduce a concept of ant-like dynamic  
variable substitution in the future.

Now back down to Earth... The way to customize that now is via a  
custom DataSourceFactory class:

http://cayenne.apache.org/doc/api/org/apache/cayenne/conf/DataSourceFactory.html

This interface can be implemented in your code to do whatever your app  
needs to do. You should enter the full class name the custom  
implementation under DataNode -> DataSource Factory in the Modeler and  
then Cayenne will pick it up.

Andrus


On Jun 16, 2008, at 7:55 AM, John Armstrong wrote:

> Hello Cayenne people,
>  First off, thank god for Cayenne. Its made my life a lot better and
> Hibernate is but a nightmare now. Thanks.
>
> Ok so my issue. I have a stand-alone app. In this app it uses the ant
> api to create a derby database in the users home directory. Some
> snippets:
>
> I config ant as :
> 		p.setProperty("dbFile", System.getProperty("user.home")
> 				+ "/portfolioDB");
>
> And then my build.xml says:
> <database url="jdbc:derby:${dbFile}"
> driverClassName="org.apache.derby.jdbc.EmbeddedDriver" username=""
> password="" />
>
> This allows me to inject my ddl into the database on first run and
> have the database be localized to the user account across platforms.
>
> I need a way to inject this same ${dbFile} context into the
> *Node.driver file so that Cayenne accesses the database I just created
> and populated at first run.
>
> Currently mine says:
>
> <url value="jdbc:derby:/portfolioDB;create=true"/>
>
> Which obviously is not dynamic. It would be great if I could set it to
> <url value="jdbc:derby:${dbFile};create=true"/>
>
> Is this possible? I am imagining a way to set an environment variable
> or some sort of custom config class that sets this. This app is
> launched from a webstart so rewriting the config file is not a good
> answer for me unless I absolutely have to. That would obviously
> require a custom config class of some sort but is a level of
> complexity that feels unnecessary.
>
> Thanks, this is a bit into the internals for me and I lose my way  
> quickly.
>
> John-
>