Question

这是我的数据结构： Imgur

我正在尝试获取allergyId1和allergyId2的值。有什么方法可以分别获取“过敏原”和“描述”的值吗？我想将这些值分配给另一个名为Allergy的类，并将它们添加到ArrayList中。例如：

Allergy allergy = new Allergy();
ArrayList<Allergy> allergies = new ArrayList<>();

// Data of "allergyId1"
allergy.setAllergen(the value of allergen);
allergy.setDescription(the value of description);

allergies.add(allergy);

我试图将返回的对象转换为Json对象，但是我认为必须有一种更有效的方法来从Firestore获取数据。

private void retrieveAllergiesData() {
        FirebaseUser user = mAuth.getCurrentUser();
        DocumentReference ref = db.collection(user.getUid()).document("allergies");

        ref.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                if (task.isSuccessful()) {
                    DocumentSnapshot document = task.getResult();
                    if (document.exists()) {
                        Map<String, Object> tmp = new HashMap<>();
                        tmp = document.getData();

                        for (Map.Entry<String, Object> entry : tmp.entrySet()) {
                            Log.d("allergy", entry.getKey() + ":" + entry.getValue().toString());
                        }

                    } else {
                        Log.d("fb", "No such document");
                    }
                } else {
                    Log.d("fb", "get failed with ", task.getException());
                }
            }
        });

    }

这就是我得到的 Imgur

Answer 1

这就是它的工作方式。就性能而言，它没有比处理文档中返回的Map更为有效的方法。

尽管如此，您不必使用它就不必创建新地图：

Map<String, Object> tmp = new HashMap<>();
tmp = document.getData();

可以这样简化：

Map<String, Object> tmp = document.getData();

Answer 2

使用构造函数和Allergy get

创建类set

private class Allergy  {

        private String allergen;
        private String description;

        public Allergies() {

        }

        public Allergies(String allergen, String description) {
            this.allergen = allergen;
            this.description = description;
        }

        public String getAllergen() {
            return allergen;
        }

        public void setAllergen(String allergen) {
            this.allergen = allergen;
        }

        public String getDescription() {
            return description;
        }

        public void setDescription(String description) {
            this.description = description;
        }
    }

然后将Object替换为Allergy。这可能适合您的情况。

private void retrieveAllergiesData() {
        FirebaseUser user = mAuth.getCurrentUser();
        DocumentReference ref = db.collection(user.getUid()).document("allergies");

        ref.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                if (task.isSuccessful()) {
                    DocumentSnapshot document = task.getResult();
                    if (document.exists()) {
                        Map<String, Allergy> tmp = new HashMap<>();
                        tmp = document.getData();

                        for (Map.Entry<String, Allergy> entry : tmp.entrySet()) {
                            String allergen = entry.getValue().getAllergen();
                            String description = entry.getValue().getDescription();
                        }

                    } else {
                        Log.d("fb", "No such document");
                    }
                } else {
                    Log.d("fb", "get failed with ", task.getException());
                }
            }
        });

    }

有什么方法可以从Firestore获取“对象”的值吗？

2 个答案: