CODEWITHSUNDEEP
androidandroid-roomandroid-livedata
user3074140
user3074140

Reputation: 857

Room livedata not correct

I have this query in my DAO

@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insertFolders(folderList: List<Folder>)

@Query("select * from attachments_folders where companyId = :companyId")
fun getFoldersByCompanyId(companyId: Int): LiveData<List<Folder>>

I have this ViewModel

class FolderViewModel :ViewModel(){
private val folders: MutableLiveData<List<Folder>> by lazy {
    MutableLiveData<List<Folder>>().also {
        loadFolders()
    }
}

fun getFolders(): LiveData<List<Folder>> {
    return folders
}

private fun loadFolders() {
    FolderDao().getFoldersByCompanyId(Prefs.getInt(PreferenceKeys.COMPANY_ID, 0))
}

}

and then this in my activity

FolderViewModel model = ViewModelProviders.of(this).get(FolderViewModel.class);

model.getFolders().observe(this, new Observer<List<Folder>>() {
            @Override public void onChanged(@Nullable List<Folder> folders) {
                if(folders != null) {
                    if (folders.size() != 0) {
                        Fragment companyFragment = AttachmentsListFragmentFactory.newFolderAttachmentsFragment(new ArrayList<>(folders), getJobId());
                        ft.replace(android.R.id.content, companyFragment);
                        currentFragment = companyFragment;
                    } else {
                        Fragment companyFragment = AttachmentsListFragmentFactory.newCompanyAttachmentsFragment(false, getJobId());
                        ft.replace(android.R.id.content, companyFragment);
                        currentFragment = companyFragment;
                    }
                }
            }
        });

It keeps hitting the else block. There are 3 folders in the database. so i dont get why its doing that and if there is a way to rectify this because if there are folders in the db it should use the if fragment not the else one.

inserting folders 

FolderDao().insertFolders(
                    Gson().fromJson<List<Folder>>(JsonHelper.getArraylistFromJson(response.body()?.string(), "folderList"),
                            object : TypeToken<List<Folder>>() {}.type))

EDIT: It seems that folders always seems to be null

Upvotes: 0

Views: 54

Answers (1)

Froyo
Froyo

Reputation: 18487

The issue is here with the usage of also. 

private val folders: MutableLiveData<List<Folder>> by lazy {
  MutableLiveData<List<Folder>>().also {
     loadFolders()
  }
}

Definition of also

public inline fun <T> T.also(block: (T) -> Unit): T {
  contract {
    callsInPlace(block, InvocationKind.EXACTLY_ONCE)
  }
  block(this)
  return this
}

As you can see, loadFolders() in also would not change anything. So you are not setting anything to the live data.

You should directly return 

fun getFolders(): LiveData<List<Folder>> {
    return loadFolders()
}

Using lazy is probably not a right choice since you may want to change the folder id.

Upvotes: 1

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