Android Paging 3 library-对于来自Room数据库的分页数据,数据流在数据更改时变为空
我正在尝试使用android Paging 3(版本3.0.0-SNAPSHOT)从房间数据库(无远程数据源)分页数据 最初,页面成功加载数据,但当一个新的“条目”添加到数据库中,并且我返回到此页面时,collectLatest被触发,但没有加载数据(“pagingData”条目列表为空) 这是我的疑问:Android Paging 3 library-对于来自Room数据库的分页数据,数据流在数据更改时变为空,android,paging,android-paging-library,room,android-paging-3,Android,Paging,Android Paging Library,Room,Android Paging 3,我正在尝试使用android Paging 3(版本3.0.0-SNAPSHOT)从房间数据库(无远程数据源)分页数据 最初,页面成功加载数据,但当一个新的“条目”添加到数据库中,并且我返回到此页面时,collectLatest被触发,但没有加载数据(“pagingData”条目列表为空) 这是我的疑问: @Query("SELECT * FROM entry ORDER BY dateTime DESC") fun getAll() : PagingSource&
@Query("SELECT * FROM entry ORDER BY dateTime DESC")
fun getAll() : PagingSource<Int, Entry>
在我的片段中,我观察到如下数据:
iewLifecycleOwner.lifecycleScope.launch {
homeViewModel.flow.collectLatest { pagingData ->
adapter.submitData(pagingData)
}
}
这是我的适配器:
class EntriesAdapter( val context : Context, private val onClick: (String)->Unit) :
PagingDataAdapter<Entry , RecyclerView.ViewHolder>(diffCallback)
{
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): EntryViewHolder
= EntryViewHolder(
DataBindingUtil.inflate(
LayoutInflater.from(parent.context),
R.layout.item_entry, parent, false
) , onClick)
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
var entry = getItem(position)
if (entry != null) {
(holder as EntryViewHolder).bindTo(entry);
}
}
companion object {
//This diff callback informs the PagedListAdapter how to compute list differences when new
private val diffCallback = object : DiffUtil.ItemCallback<Entry>() {
override fun areItemsTheSame(oldItem: Entry, newItem: Entry): Boolean =
oldItem.id == newItem.id
override fun areContentsTheSame(oldItem: Entry, newItem: Entry): Boolean =
oldItem.id == newItem.id
}
}
inner class EntryViewHolder( val binding : ItemEntryBinding ,val onCLick:
(String)->Unit ) : RecyclerView.ViewHolder(binding.root) {
var entry:Entry? = null
fun bindTo(entry: Entry) {
this.entry = entry
with(binding) {
entryItem = entry
cardView.setOnClickListener{
onCLick
}
executePendingBindings()
}
}
}
}
class EntriesAdapter(val-context:context,private-val-onClick:(String)->Unit):
PagingDataAdapter(diffCallback)
{
重写CreateViewHolder(父级:ViewGroup,viewType:Int):EntryViewHolder
=入口视图支架(
充气(
LayoutFlater.from(父上下文),
R.layout.item_条目,父项,false
),onClick)
覆盖onBindViewHolder(holder:RecyclerView.ViewHolder,位置:Int){
var条目=getItem(位置)
if(条目!=null){
(持有人作为EntryViewHolder)。bindTo(条目);
}
}
伴星{
//此差异回调通知PagedListAdapter如何在新建时计算列表差异
private val diffCallback=对象:DiffUtil.ItemCallback(){
覆盖项相同(旧项:条目,新项:条目):布尔值=
oldItem.id==newItem.id
覆盖内容相同(旧项:条目,新项:条目):布尔值=
oldItem.id==newItem.id
}
}
内部类EntryViewHolder(val绑定:ItemEntryBinding,val onCLick:
(字符串)->单位):RecyclerView.ViewHolder(binding.root){
变量条目:条目?=null
趣味宾托(条目:条目){
this.entry=entry
有(约束力){
entryItem=入口
cardView.setOnClickListener{
onCLick
}
executePendingBindings()
}
}
}
}
我与您的问题类似,只是在添加新项目后忘记调用entriesAdapter.refresh()
。我与您的问题类似,只是在添加新项目后忘记调用entriesAdapter.refresh()
class EntriesAdapter( val context : Context, private val onClick: (String)->Unit) :
PagingDataAdapter<Entry , RecyclerView.ViewHolder>(diffCallback)
{
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): EntryViewHolder
= EntryViewHolder(
DataBindingUtil.inflate(
LayoutInflater.from(parent.context),
R.layout.item_entry, parent, false
) , onClick)
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
var entry = getItem(position)
if (entry != null) {
(holder as EntryViewHolder).bindTo(entry);
}
}
companion object {
//This diff callback informs the PagedListAdapter how to compute list differences when new
private val diffCallback = object : DiffUtil.ItemCallback<Entry>() {
override fun areItemsTheSame(oldItem: Entry, newItem: Entry): Boolean =
oldItem.id == newItem.id
override fun areContentsTheSame(oldItem: Entry, newItem: Entry): Boolean =
oldItem.id == newItem.id
}
}
inner class EntryViewHolder( val binding : ItemEntryBinding ,val onCLick:
(String)->Unit ) : RecyclerView.ViewHolder(binding.root) {
var entry:Entry? = null
fun bindTo(entry: Entry) {
this.entry = entry
with(binding) {
entryItem = entry
cardView.setOnClickListener{
onCLick
}
executePendingBindings()
}
}
}
}