How update Room DB with API response if there is not data? - retrofit2

Question

I am trying to update my database (room) with the response of my call api if my database table is empty and return to my recyclerview
API
#GET("user/patient/")
Flowable<ResponsePatient> getPatients(#Header("Authorization") String userToken);
FactoryData.class
public Flowable<List<Patient>> getPatientFromApi(){
String token = preferences.getValue(SDConstants.token);
return apiNetwork.getPatients(token).map(new Function<ResponsePatient, List<Patient>>() {
#Override
public List<Patient> apply(ResponsePatient responsePatient) throws Exception {
return PatientMapper.transform(responsePatient);
}
});
}
public Flowable<List<Patient>> listPatient(){
return appDataBase.patientDao().listPatient()
.switchIfEmpty(getPatientFromApi())
.doOnNext(s -> appDataBase.patientDao().saveAll(s));
}
I not sure how to do this. I appreciate any help.

Answer 1

Finally I can solve my problem.
public Flowable<List<Patient>> getPatient(){
return getPatientFromlocal()
.take(1)
.filter(list -> !list.isEmpty())
.switchIfEmpty(
Flowable.defer(() -> getPatientFromApi()));
}
public Flowable<List<Patient>> getPatientFromlocal(){
return appDataBase.patientDao().listPatient();
}
public Flowable<List<Patient>> getPatientFromApi(){
String token = preferences.getValue(SDConstants.token);
return apiNetwork.getPatients(token).map(new Function<ResponsePatient, List<Patient>>() {
#Override
public List<Patient> apply(ResponsePatient responsePatient) throws Exception {
return PatientMapper.transform(responsePatient);
}
}).doOnNext(new Consumer<List<Patient>>() {
#Override
public void accept(List<Patient> patients) throws Exception {
appDataBase.patientDao().saveAll(patients);
}
});
}