[TYPO3-mvc] Relations between to models mapped on foreign tables

[Beta Patch]

Hi there,

i have set up to models with the extension builder.
One called subsite, the other template.
subsite should be mapped on table pages and template on table sys_template.
I configured it to be an 1:n relation.

the ext_typoscript_setup.txt looks like this:

config.tx_extbase {
    persistence {
        classes {
            Tx_Blatest_Domain_Model_Subsite {
                mapping {
                    tableName = pages
                    columns {
                    	title.mapOnProperty = title
                    }
                }
            }
            
            Tx_Blatest_Domain_Model_Template {
                mapping {
                    tableName = sys_template
                    columns {
                    	title.mapOnProperty = title
                    	constants.mapOnProperty = constants
                    }
                }
            }
            
    	}
    }
}

In the SubsiteContoller I have an Index action. It should echo the titles of all found pages and their templates.

	public function indexAction() {
		$subsites = $this->subsiteRepository->findAll();
		foreach ($subsites as $subsite) {
			echo $subsite->getTitle()."<br>\n";
			$templates = $subsite->getTemplates();
			foreach ($templates as $template) {
				echo "<pre>\t".$template->getTitle()."</pre><br>\n";
			}
		}
	}

The Problem is: It does not find any Templates. Do I have to configure the key of the foreign table relation? If so, how?

I'm a bloody beginner in extbase, and it would be great if someone can give me a hint.