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Question

I have DBManager class for CRUD operations and I want to use it across application, I know that Realm objects can only be accessed on the thread they were created and for that reason I'm unable to use My DBManager class methods inside threads and etc...

what I want is to call updateUploadingFileStatus method declared inside DBManager, from thread which is running inside service.

this is my DBManager class

object DbManager {
private val realm: Realm by lazy { Realm.getDefaultInstance() }

fun saveOrRemoveUploadFile(filePath: String, save: Boolean){
    val model = getUploadModelByFilePath(filePath)
    realm.executeTransaction {
        model.markedForUpload = save
        realm.insertOrUpdate(model)
    }
}

fun updateUploadingFileStatus(filePath: String, uploaded: Boolean){
    val model = getUploadModelByFilePath(filePath)
    realm.executeTransaction {
        model.uploadedStatus = uploaded
    }
}

fun getFilesForUpload() : List<UploadModel> {
    return realm
            .where(UploadModel::class.java)
            .equalTo("markedForUpload",true)
            .equalTo("uploadedStatus",false)
            .findAll()
}

fun getUploadModelByFilePath(filePath: String) : UploadModel {
    return realm.where(UploadModel::class.java).equalTo("filePath",filePath).findFirst() ?: UploadModel(filePath)
}

}

Calling this method from another thread throws java.lang.IllegalStateException Realm access from incorrect thread. How can be solved this problem? what is a good style for doing things like that?

Answer 1

Change your function code as follow:

 public void updateUploadingFileStatus(final String filePath, final Boolean uploaded) {
        mRealm.executeTransactionAsync(new Realm.Transaction() {
            @Override
            public void execute(Realm realm) {
                UploadModel model = getUploadModelByFilePath(filePath);
                model.uploadedStatus = uploaded;
            }
        });
    }

Time ago I solved this problem by using a new Transaction. I also was using a Singleton class to access the RealmDB, and was calling this function inside a response handler from network. This should work.