按字母顺序过滤 Firestore 数据以对 Google Cloud 中的文档读取进行分类/减少

如何解决按字母顺序过滤 Firestore 数据以对 Google Cloud 中的文档读取进行分类/减少

基于 Cloud Firestore does not support Full-Text Search 到目前为止的事实，我决定问这个 question 前一段时间。受到 write-up 的 Alex Mamo 的启发，我能够通过实现以下文章中的内容在 Cloud Firestore 上模拟全文搜索场景。

ProductRepository 类的 getProductNameListMutableLiveData() 方法一次获取所有 productNames

class ProductRepository {
    private FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
    private DocumentReference productSearchRef = rootRef.collection("data").document("productSearch");
    private CollectionReference productsRef = rootRef.collection("SearchList");

    MutableLiveData<List<String>> getProductNameListMutableLiveData() {
        MutableLiveData<List<String>> productNameListMutableLiveData = new MutableLiveData<>();
        productSearchRef.get().addOnCompleteListener(productNameListTask -> {
            if (productNameListTask.isSuccessful()) {
                DocumentSnapshot document = productNameListTask.getResult();
                if (document.exists()) {
                    List<String> productNameList = (List<String>) document.get("productNames");
                    productNameListMutableLiveData.setValue(productNameList);
                }
            } else {
                Log.d("Name List Error: ",productNameListTask.getException().getMessage());
            }
        });
        return productNameListMutableLiveData;
    }

    MutableLiveData<String> getProductPriceMutableLiveData(String productName) {
        MutableLiveData<String> productPriceMutableLiveData = new MutableLiveData<>();
        productsRef.whereEqualTo("prodName",productName).get().addOnCompleteListener(productTask -> {
            if (productTask.isSuccessful()) {
                if (productTask.isSuccessful()) {
                    for (QueryDocumentSnapshot document : productTask.getResult()) {
                        productPriceMutableLiveData.setValue(document.toObject(Product.class).itemLink);
                    }
                }
            } else {
                Log.d("Item Link Error: ",productTask.getException().getMessage());
            }
        });
        return productPriceMutableLiveData;
    }
}

现在我的问题是：

1. 我们如何通过按第一个字母搜索来改进/减少 Cloud Firestore 上的 READ-COUNT，这可以优化大型数据集上的案例。
2. 我们如何从这样的东西中有序地获取数据，以便每当数据传递到下面时，它只读取必要的第一个字母
   

   

   
   

private void getProductNameList() {
        productViewModel.getProductNameListLiveData().observe(this,productNameList -> {
            productNamesAdapter = new ProductNamesAdapter(this,productNameList);
            Log.d("ProductName List---","getProductNameList: " + productNameList);
            autoComplete.setAdapter(productNamesAdapter);
        });
    }

这是允许实现过滤器/搜索逻辑的过滤器方法

private Filter productNameFilter = new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            FilterResults results = new FilterResults();
            List<String> suggestionList = new ArrayList<>();
            if (constraint == null || constraint.length() == 0) {
                suggestionList.addAll(productNameListFull);
            } else {
                String filterPattern = constraint.toString().toLowerCase().trim();
                for (String productName : productNameListFull) {
                    if (productName.toLowerCase().contains(filterPattern)) {
                        suggestionList.add(productName);
                    }
                }
            }
            results.values = suggestionList;
            results.count = suggestionList.size();
            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint,FilterResults results) {
            List<String> productNameList = (List<String>) results.values;
            if (productNameList != null) {
                clear();
                addAll(productNameList);
            }
            notifyDataSetChanged();
        }

        @Override
        public CharSequence convertResultToString(Object resultValue) {
            return (String) resultValue;
        }
    };

您可以找到完整的代码here