Update query when related entities change

[alekop]

Is there a way for an observable query to detect when a related entity changes, and notify its subscribers? The following uses a one-to-one relationship between a person and an address. I would like the person query to be notified when a person's address changes.

@Entity
data class Person(@Id val id: Long = 0) {
    lateinit var homeAddress: ToOne<Address>
}

@Entity
data class Address(@Id var id: Long = 0,
    val street: String
)

// Build a query for the parent
val query = boxStore.boxFor<Person>().query().build()
query.find()

// I want to be notified when the address changes
query.subscribe(...)

// Update the relationship
person.homeAddress.target = Address(street= "...")
boxStore.boxFor<Address>.put(newAddress) // persists, but the person query does not get notified

This updates the address box as expected, but the person query is not notified. Any way to accomplish that?

[greenrobot-team]

The query is set up to only listen for changes of the entity used to build the query. However, you could just add another observer on the Address entity:
boxStore.subscribe(Address.class).on(...).observer(..)
-ut

[greenrobot-team]

Also see #300.

Edit: also see #59. -ut

[Ekalips]

I vote up for this issue.
Maybe there is some possibility to add some kind of .deep() into subscription builder? So subscription will track not only main entity updates but also related data changes.

[squeeish]

This will be awesome for LiveData too

[squeeish]

Is this in 2.1.0?

[amgadserry]

is there any plans to implement this feature or even a workaround ? @greenrobot-team

[greenrobot-team]

@amgadserry A workaround is mentioned in the first comment: #387 (comment)

-Uwe

[amgadserry]

@greenrobot-team thanks i was using the current code so is there a way to do it on a query instead of the box itself as i cannot create a query after .subscribe on box

    fun getPopulatedAccounts(): Observable<List<AccountEntity>> {
        val zipper: BiFunction<
                List<AccountEntity>,
                List<RequestEntity>,
                List<AccountEntity>> = BiFunction { accounts, _ -> 
                    accounts.forEach { it.requests.reset() } // requests is a backlink so it is cached
                    accounts
                }

        val accountsQueryObservable = RxQuery.observable(accountsDao.findAll())

        val requestsQueryObservable = RxQuery.observable(requestDao.findAll())

        return Observable.combineLatest(accountsQueryObservable, requestsQueryObservable, zipper)
    }

Ps: I simplified the query just for the sake of the example
notice the manual reset for backlinks
the problem gets messier when u r using smth like Diffutil which then you would need smth like this instead because resetting the requests would simply change both old and new version which would result in ur data not updating due to the diffutil thinking that objects are the same

accounts.map {
                val _copy = it.copy()
                _copy.requests.reset()
                _copy
            }

Thanks for the great effort u put in this engine though it's amazing !!

[amgadserry]

@greenrobot-team here is the final solution i went with

    fun getPopulatedAccounts(): Observable<List<AccountEntity>> {
        val zipper: BiFunction<
                Any,
                Any,
                List<AccountEntity>> = BiFunction { _, _ -> 
                    accountsDoa.findAll {
                        eager(Account_.requests)
                    }.find()
                }

        val accountsObservable = RxBoxStore.observable<Account>(accountsDoa.store)

        val requestsObservable = RxBoxStore.observable<RequestEntity>(requestDao.store)

        return Observable.combineLatest(accountsObservable, requestsObservable, zipper)
    }

let me know if there are a better workaround for rxjava. Thanks

[greenrobot-team]

Duplicate of #268