Android 使用 FirestorePagingAdapter 从多个文档中查询数据

Question

我有 collection 个用户和 collection 个食谱

我正在使用 FirestorePagingAdapter 来显示和分页数据，我想显示带有用户详细信息（姓名和照片）的食谱（标题和图像..）

我可以显示食谱，但无法在同一查询中获取用户详细信息（Firestore 中没有连接）

这是我的代码：

fun setUpHomeAdapter(){
    var mQuery: Query = firestore.collection("recipes")
    // Init Paging Configuration
    val config = PagedList.Config.Builder()
        .setInitialLoadSizeHint(5)
        .setEnablePlaceholders(true)
        .setPrefetchDistance(5)
        .setPageSize(5)
        .build()
    // Init Adapter Configuration
    val options = FirestorePagingOptions.Builder<Recipe>()
        .setLifecycleOwner(this)
        .setQuery(mQuery, config, Recipe::class.java)
        .build()

    mAdapter = RecipesHomePagingAdapter(options, this)

    homeRecyclerView.adapter = mAdapter
}

我的适配器：

class RecipesHomePagingAdapter(
options: FirestorePagingOptions<Recipe>,
val listener: RecipesHomeViewHolder.OnItemRecipeClickListener) : FirestorePagingAdapter<Recipe, 
                                                                 RecipesHomeViewHolder>(options) {


override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecipesHomeViewHolder {
    val view =
            LayoutInflater.from(parent.context).inflate(
                R.layout.fragment_recipe_home_item,
                parent,
                false
            )

    return RecipesHomeViewHolder(view, listener)
}


override fun onBindViewHolder(holder: RecipesHomeViewHolder, position: Int, recipe: Recipe) {
    holder.bind(recipe)
}

我的 ViewHolder :

 class RecipesHomeViewHolder(itemView: View, private val listener: OnItemRecipeClickListener) :
RecyclerView.ViewHolder(itemView), View.OnClickListener {

private var imageRecipe: ImageView = itemView.findViewById(R.id.image_recipe)
private var title: TextView = itemView.findViewById(R.id.title)
private var nameuser: TextView = itemView.findViewById(R.id.user_name)
private var calories: TextView = itemView.findViewById(R.id.calories_textview)
private var layout_image_recipe: RelativeLayout =
    itemView.findViewById(R.id.layout_image_recipe)
private  var id_recipe: String?=null

fun bind(recipe: Recipe) {
    Glide
        .with(imageRecipe.context)
        .load(recipe.imageUrl)
       // .diskCacheStrategy(DiskCacheStrategy.ALL)
        .placeholder(R.drawable.ic_recipe_placeholder)
        .error(R.drawable.ic_recipe_placeholder)
        .into(imageRecipe)

    calories.text = recipe.calories.toString() + " Calories"
    title.text = recipe.title
    //nameuser.text = recipe.user_uid

}

init {
    layout_image_recipe.setOnClickListener(this)
}

override fun onClick(v: View?) {
    val position = adapterPosition
    if (position != RecyclerView.NO_POSITION) {
        listener.onViewClick(v!!, position, id_recipe)

    }
}

interface OnItemRecipeClickListener {
    fun onViewClick(v: View, position: Int, id_recipe:String?)

}

}

感谢您帮助解决问题！[=15=]

Answer 1

遗憾的是，您不能将两个查询传递给 FirestorePagingOptions，只允许一个。我能想到的最简单的事情是将用户详细信息添加为 Recipe 对象中的属性。如果您不能这样做，还有另一种选择，您可以在其中创建两个单独的查询并将结果传递给适配器，但在这种情况下，您将无法再使用 FirestorePagingAdapter。但是，仍然可以通过将查询游标与 limit() 方法结合使用来归档分页。为此，我建议您从以下 post:

中查看我的回答

然后看看这个 video 以便更好地理解。

如果您想使用现代 Paging 3 库，请查看以下文章：

How to paginate Firestore using Paging 3 on Android?

Android 使用 FirestorePagingAdapter 从多个文档中查询数据

Android query data using FirestorePagingAdapter from multiple documents

android

firebase

google-cloud-firestore

firebaseui

android-paging