无效数据。不支持的类型：com.google.firebase.firestore.QueryDocumentSnapshot

Question

我正在使用以下代码从Firestore数据库中获取数据：

ImageDataModel.kt

class ImageDataModel @Inject constructor(private val firebaseFirestore: FirebaseFirestore) : ViewModel() {


    var isLoading  = MutableLiveData<Boolean>()
    var isPagerLoading  = MutableLiveData<Boolean>()

    var apiError = MutableLiveData<String>()

    var imgResponse = MutableLiveData<QuerySnapshot>()


    fun getPhotosByOrder(orderBy: String){
        isLoading.value = true
        var query: Query
        query = firebaseFirestore.collection(DBConstant.PHOTO.tableNm)
            .orderBy(orderBy)
            .limit(12)
        query.get()
            .addOnSuccessListener { documentSnapshots ->
                // Get the last visible document
                if(documentSnapshots != null){
                    isLoading.value = false
                    imgResponse.value = documentSnapshots
                }else{
                    isLoading.value = false
                    apiError.value = Constant.SERVER_CONNECTION_ERROR
                }
            }
            .addOnFailureListener {
                isLoading.value = false
                apiError.value = it.message
            }

    }

    fun getPhotosByOrderPagination(orderBy: String, lastVisible: DocumentSnapshot?){
        isPagerLoading.value = true
        var query: Query
        query = firebaseFirestore.collection(DBConstant.PHOTO.tableNm)
            .orderBy(orderBy)
            .startAfter(lastVisible)
            .limit(6)

        query.get()
            .addOnSuccessListener { documentSnapshots ->
                // Get the last visible document
                if(documentSnapshots != null){
                    isPagerLoading.value = false
                    imgResponse.value = documentSnapshots
                }else{
                    isPagerLoading.value = false
                    apiError.value = Constant.SERVER_CONNECTION_ERROR
                }
            }
            .addOnFailureListener {
                isPagerLoading.value = false
                apiError.value = it.message
            }

    }

}

活动分类：

private var lastVisible: DocumentSnapshot?= null

private fun bindObservers(){
        imageDataModel.isLoading.observe(this, androidx.lifecycle.Observer {
            if(it){
                llPbLoading.visibility = View.VISIBLE
                rvListFragBrowse.visibility = View.GONE
            }else{
                llPbLoading.visibility = View.GONE
                rvListFragBrowse.visibility = View.VISIBLE
            }
        })

        imageDataModel.apiError.observe(this, androidx.lifecycle.Observer {
            toast(it, activity!!)
        })

        imageDataModel.imgResponse.observe(this, androidx.lifecycle.Observer {
            photosList.clear()
            if(it.size() > 0){
                lastVisible = it.documents[it.size() - 1]
                Log.e("BrowseFrag","Last Item Name: "+lastVisible!!)
                for(item in it){
                    var photoData = item.toObject(PhotosData::class.java)
                    photoData.id = item.id
                    photosList.add(photoData)
                    mAdapterBrowse.notifyDataSetChanged()

                }
            }
        })

    }

    private fun getPhotosByOrder(orderBy: String){
        if(lastVisible == null){
            imageDataModel.getPhotosByOrder(orderBy)
        }else{
            imageDataModel.getPhotosByOrderPagination(orderBy, lastVisible)
        }
    }

我收到以下错误日志：

  

java.lang.IllegalArgumentException：无效的数据。不支持的类型：com.google.firebase.firestore.QueryDocumentSnapshot               com.google.firebase.firestore.core.UserData $ ParseContext.createError（com.google.firebase：firebase-firestore @@ 17.1.5：293）               在com.google.firebase.firestore.UserDataConverter.parseScalarValue（com.google.firebase：firebase-firestore @@ 17.1.5：405）               在com.google.firebase.firestore.UserDataConverter.parseData（com.google.firebase：firebase-firestore @@ 17.1.5：254）               在com.google.firebase.firestore.UserDataConverter.parseQueryValue（com.google.firebase：firebase-firestore @@ 17.1.5：186）               在com.google.firebase.firestore.Query.boundFromFields（com.google.firebase：firebase-firestore @@ 17.1.5：669）               在com.google.firebase.firestore.Query.startAfter（com.google.firebase：firebase-firestore @@ 17.1.5：517）               在com.firestoredemo.viewmodel.ImageDataModel.getPhotosByOrderPagination（ImageDataModel.kt：64）               在com.firestoredemo.ui.fragment.BrowseFragment.getPhotosByOrder（BrowseFragment.kt：228）               在com.firestoredemo.ui.fragment.BrowseFragment.access $ getPhotosByOrder（BrowseFragment.kt：44）               在com.firestoredemo.ui.fragment.BrowseFragment $ setListener $ 2.onLoadMore（BrowseFragment.kt：153）               在com.firestoredemo.adapter.BrowseResultAdapter $ 1.onScrolled（BrowseResultAdapter.kt：57）