A few days back I had chance to work on a googleApp using GORM-JPA plugin,version (0.7.1). I came across a few problems which are as given below.
Consider the domain : Country -> has many States.
At first it appeared that the one to many relationships are to be managed using annotations like :
Country {
@OneToMany(mappedBy = "state")
List states
}
State state {
@ManyToOne
State state
}
The Country.get() worked fine but State.get() did not work. I think it is due to the fact that Big Table stores states as multivalued attributes of the Country. So to make it work I myself added a field (countryId) to State domain, storing the Id of the Country it belongs to as foreign key. So everytime I needed to find the State from its Id attribute, I first used to search all the States belonging to a Country, and then from these states search for a state with a particular id.
List states = State.findAll("SELECT s FROM State s WHERE s.countryId='${params.countryId}'")
def pollOptionInstance = pollOptions.find {it.id == params.id.toLong()}
Domain.findAllBy() and Domain.findBy() do not seem to work. I used Domain.findAll{query} most of the time to query a domain.
Each save() operation needs to be contained in a transaction
Only one object can be saved in one transaction
I couldn’t save State object with the reference of the Country object in it. It did not allow me, so I stored the countryId instead of the whole object (which exactly is what gorm does for you). So this meant I had to manage hasMany relationships on my own, by storing the refenceIds instead of the objects itself (so annotations were of no use).
Hope this helps. You are welcome to share your thoughts on it.
Imran Mir
imran@intelligrap.com
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