搜索FireBase实时数据库

Question

查看其他关于堆栈溢出的问题，有人说这可能是因为valueEventListener的位置不正确，但...不是吗？我正在钻进食物条目/营养条目，但我不知道如何钻进更深。没办法匿名给孩子打电话？我尝试调用childEventListener而不是valueEventListener，其他的都一样，但我再也没有得到那个消息，但我仍然无法检索到我想要的数据。

        DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
        Query allEntries = ref.child("Users").child(profile.getProfileKey()).child("Nutrition entries").orderByChild("foodTitle").equalTo(search);
// Query for all entries with a certain child with value equal to something


final ArrayList<nutritionEntry> searchResults = new ArrayList<nutritionEntry>();
// Add listener for Firebase response on said query
        ValueEventListener valueEventListener = new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                for(DataSnapshot post : dataSnapshot.getChildren() ){
                    nutritionEntry ex = post.getValue(nutritionEntry.class);
                    searchResults.add(ex);
                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Log.d("Error", "Search Cancled");
            }
        };
        allEntries.addListenerForSingleValueEvent(valueEventListener);

        if(searchResults.isEmpty()){
            TableRow tr = new TableRow(nutritionTracker.this);
            TextView tv1 = new TextView(nutritionTracker.this);
            tv1.setText("No Results");
        }else{
        for(final nutritionEntry e : searchResults) {
            //code to display the entries
}

编辑：

谢谢你到目前为止的帮助。根据下面Hasan的回答，我更新了onDataChanged中的for循环，这样我得到的是children post的值，而不是DataNapShot，这是一个问题。我还更新了代码，转到正确的UID，然后是nutrition条目，这也会引起问题。我不再收到同样的信息了，但我还是一无所获。当我进入调试器时，没有调用onDataChange，因此resultsList为空。onCancled在更新代码时从未被调用，这里是公开的JSON的屏幕截图，还有我的nutritionEntry类。它有默认构造函数、包含所有参数的构造函数、所有getter和setters以及所有字段与FireBase中的内容匹配：

public class nutritionEntry {
    public String date;
    public String foodTitle;
    public int calories;
    public int protein;
    public int totalCarb;
    public int fiber;
    public int sugar;
    public int totalFat;
    public int trans;
    public int saturated;
    public int unsaturated;
    public String submittedBy;


    public nutritionEntry(String date,String foodTitle, int calories, int protein, int totalCarb, int fiber, int sugar, int totalFat, int trans, int saturated, int unsaturated, String submitter) {
        this.date = date;
        this.foodTitle = foodTitle;
        this.calories = calories;
        this.protein = protein;
        this.totalCarb = totalCarb;
        this.fiber = fiber;
        this.sugar = sugar;
        this.totalFat = totalFat;
        this.trans = trans;
        this.saturated = saturated;
        this.unsaturated = unsaturated;
        this.submittedBy = submitter;
    }

    public nutritionEntry() {}

    public String getDate() {
        return date;
    }

    public String getFoodTitle() {
        return foodTitle;
    }

    public int getCalories() {
        return calories;
    }

    public int getProtein() {
        return protein;
    }

    public int getTotalCarb() {
        return totalCarb;
    }

    public int getFiber() {
        return fiber;
    }

    public int getSugar() {
        return sugar;
    }

    public int getTotalFat() {
        return totalFat;
    }

    public int getTrans() {
        return trans;
    }

    public int getSaturated() {
        return saturated;
    }

    public int getUnsaturated() {
        return unsaturated;
    }

    public String getSubmittedBy() {
        return submittedBy;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public void setFoodTitle(String foodTitle) {
        this.foodTitle = foodTitle;
    }

    public void setCalories(int calories) {
        this.calories = calories;
    }

    public void setProtein(int protein) {
        this.protein = protein;
    }

    public void setTotalCarb(int totalCarb) {
        this.totalCarb = totalCarb;
    }

    public void setFiber(int fiber) {
        this.fiber = fiber;
    }

    public void setSugar(int sugar) {
        this.sugar = sugar;
    }

    public void setTotalFat(int totalFat) {
        this.totalFat = totalFat;
    }

    public void setTrans(int trans) {
        this.trans = trans;
    }

    public void setSaturated(int saturated) {
        this.saturated = saturated;
    }

    public void setUnsaturated(int unsaturated) {
        this.unsaturated = unsaturated;
    }

    public void setSubmittedBy(String submittedBy) {
        this.submittedBy = submittedBy;
    }




}

第二次编辑：

Answer 1

if(userOrAll) {
allEntries = ref.child("Food Entries").orderByChild("foodTitle").equalTo(searchString);
}else{
allEntries = ref.child("Users").child("Nutrition entries").orderByChild("foodTitle").equalTo(searchString);
}

//this is your ref for Nutrition Entries
String UID = FirebaseAuth.getInstance().getCurrentUser().getUid();
allEntries = ref.child("Users").child(UID).child("Nutrition Entries");

现在这一点很重要，请确保在您的类nutritionentry中的字段与FireBase中的名称匹配：

例如：

class nutritionEntry{

//these must be named exactly like in the database
String foodTitle;
......
......
......
......

//constructor must be generated for all

//getters and setters must be generated for all

}

最后读取值：

     //this is your ref for Nutrition Entries
     String UID = FirebaseAuth.getInstance().getCurrentUser().getUid();
     allEntries = ref.child("Users").child(UID).child("Nutrition Entries");

    ValueEventListener valueEventListener = new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for(DataSnapshot ds : dataSnapshot.getChildren() ){
                nutritionEntry ex = ds.getValue(nutritionEntry.class);
                searchResults.add(ex);
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    };
    allEntries.addListenerForSingleValueEvent(valueEventListener);

for(DataSnapshot ds : dataSnapshot.getChildren() ){

String date = ds.child("date").getValue(String.class);
String foodTitle = ds.child("foodTitle").getValue(String.class);
int calories = ds.child("calories").getValue(Integer.class);
int protein = ds.child("protein").getValue(Integer.class);
int totalCarb = ds.child("totalCarb").getValue(Integer.class);
int fiber = ds.child("fiber").getValue(Integer.class);
int sugar = ds.child("sugar").getValue(Integer.class);
int totalFat = ds.child("totalFat").getValue(Integer.class);
int trans = ds.child("trans").getValue(Integer.class);
int saturated = ds.child("saturated").getValue(Integer.class);
int unsaturated = ds.child("unsaturated").getValue(Integer.class);
String submittedBy = ds.child("submittedBy").getValue(String.class);


nutritionEntry entry = new nutritionEntry(date,foodTitle,calories,protein,totalCarb,fiber,sugar,totalFat,trans,saturated,unsaturated,submittedBy);

searchResults.add(entry);

}