Re: [Beankeeper-discussion] unique "keys "

[Brautigam R. <de...@ne...>]

Shay Matasaro írta:
> Hi ,

Hi,

> my sample app has a company data object and a user data object, i would 
> like usernames to be unique, across the board.
> 
> i assume that maintaining this uniqueness per company is done via the 
> collection container of the company ( Set<user> company users)
> 
> how do i make sure that usernames are unique across companies(the 
> parallel of unique property on a DB column), do i have to run a GetName 
> query before each user addition?

In short, yes. The longer answer is, that BeanKeeper is Java-side only,
so you can't get part of your logic implemented in the database, like
unique names, field constraints, hard relations, etc. You must do
everything at the Java side.
Of course BeanKeeper will use optimizations on the database, but the
general direction is, that you should not need to, and if fact should
not be able to do database (low) level stuff.

Be aware also, that a persistent Set in BeanKeeper is unique always on
persistence id (so persistent instance of object), and not using the
equals() and hashCode() you implement. So Sets (and Lists also) store
relations, instead of objects in this sense.

> thanks,
> Shay

Robert.