当用户单击recyclerview中的删除按钮时,我无法从Firestore集合中删除数据。我可以从recyclerview中删除它,没有任何问题,但是我很难在适配器, View 模型和处理Firestore操作的存储库之间建立连接。
在适配器中,我从recyclerview中删除了用户单击的项目:
class ArticleAdapter : RecyclerView.Adapter<ArticleAdapter.ViewHolder>() {
var data = mutableListOf<Product>()
set(value) {
field = value
notifyDataSetChanged()
}
override fun getItemCount() = data.size
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val item = data[position]
holder.bind(item)
holder.deleteButton.setOnClickListener {
data.removeAt(position)
notifyDataSetChanged()
}
} ...
在对我的 View 模型中的Firestore集合进行查询之后,将填充recyclerview:
class ArticleViewModel(private val repository: ProductRepository) : ViewModel() {
var savedProducts: MutableLiveData<MutableList<Product>> = MutableLiveData<MutableList<Product>>()
init {
savedProducts = getProducts()
}
fun getProducts(): MutableLiveData<MutableList<Product>> {
repository.getProducts().addSnapshotListener(EventListener<QuerySnapshot> { value, e ->
if (e != null) {
savedProducts.value = null
return@EventListener
}
val savedProductsList: MutableList<Product> = mutableListOf()
for (doc in value!!) {
val item = doc.toObject(Product::class.java)
item.id = doc.id
savedProductsList.add(item)
}
savedProductsList.sortBy { i -> i.productName }
savedProducts.value = savedProductsList
})
return savedProducts
} }
然后,在片段中,我观察到saveProducts可能发生的任何更改:
class ArticleOverviewFragment : Fragment(), KodeinAware {
override val kodein: Kodein by kodein()
private val factory: ArticleViewModelFactory by instance()
private lateinit var viewModel: ArticleViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val binding: FragmentArticleOverviewBinding =
DataBindingUtil.inflate(inflater, R.layout.fragment_article_overview, container, false)
viewModel = ViewModelProviders.of(this, factory).get(ArticleViewModel::class.java)
binding.viewModel = viewModel
val adapter = ArticleAdapter()
binding.recyclerViewGoods.adapter = adapter
viewModel.savedProducts.observe(viewLifecycleOwner, Observer {
it?.let {
adapter.data = it
}
})
...
} }
有没有一种方法可以观察/保存适配器中已删除项目的ID,并将该ID从适配器“转移”到UI,从而在每次填充包含ID的字段时调用在ViewModel中声明的函数?还是应该直接从适配器访问viewmodel?不知何故,这有点不对劲...
最佳答案
声明一个局部变量
var removedPosition : Int ? = null
然后将此变量更新为deleteButton的onClick事件
holder.deleteButton.setOnClickListener {
data.removeAt(position)
removedPosition = position
notifyDataSetChanged()
}
请在Adapter(
ArticleAdapter
)中制作一种方法fun getRemoveItemPosition() : Int {
var position = removedPosition
return position;
}
它返回已删除项目的位置,并在UI(
ArticleOverviewFragment
)中调用该方法,您需要在该方法中从recyclerview获取已删除项目的位置var removedItemPosition = adapter.getRemoveItemPosition()
现在,您将使用名为
removedItemPosition
的变量获取删除项Position的值因此,您可以在UI中获取已删除项目的位置,您可以在其中调用在viewmodel中声明的函数(
ArticleViewModel
)来删除firestore集合中的特定项目。
关于android - 单击按钮后,从recyclerview中删除项目-Kotlin MVVM Firestore,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/61252600/