Help implementing RecordExists

Hello forum,
I am brand new to ZF3 and this forum and I’m loving every minute of it.

The docs on \Zend\Validator\Db\RecordExists are clear. What I need help with is identifying the [adapter] parameter. I have a ZF3 app that uses a database connection specified in [App]\config\autoload (global and local).

If anyone can point me to any documentation (or examples) on getting that value into my controller I would appreciate it.