如何在firestore中存储模型类对象列表？答案

【问题标题】：How to store list of model class objects in firestore?如何在firestore中存储模型类对象列表？
【发布时间】：2020-11-01 10:10:25
【问题描述】：

我以前使用过 firebase 实时数据库，我只是将对象列表存储在数据库中。如何在firestore数据库中存储模型类对象的arraylist？

【问题讨论】：

标签： firebase android-studio google-cloud-firestore google-cloud-functions

【解决方案1】：

将模型类对象一个一个制作并添加到一个ArrayList中，如下图：

City city1 = new City("Los Angeles", "CA", "USA",
    false, 5000000L, Arrays.asList("west_coast", "sorcal"));
City city2 = new City("Los Angeles", "CA", "USA",
        false, 5000000L, Arrays.asList("west_coast", "sorcal"));
City city3 = new City("Los Angeles", "CA", "USA",
        false, 5000000L, Arrays.asList("west_coast", "sorcal"));
ArrayList<City> list = new ArrayList<City>();
list.add(city1);
list.add(city2);
list.add(city3);

db.collection("cities").document("LA").set(list)
    .addOnSuccessListener(new OnSuccessListener<Void>() {
        @Override
        public void onSuccess(Void aVoid) {
            Log.d(TAG, "DocumentSnapshot successfully written!");
        }
    })
    .addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            Log.w(TAG, "Error writing document", e);
        }
    });

或者你也可以试试下面的方法

City city1 = new City("Los Angeles", "CA", "USA",
    false, 5000000L, Arrays.asList("west_coast", "sorcal"));
City city2 = new City("Los Angeles", "CA", "USA",
        false, 5000000L, Arrays.asList("west_coast", "sorcal"));
City city3 = new City("Los Angeles", "CA", "USA",
        false, 5000000L, Arrays.asList("west_coast", "sorcal"));
ArrayList<City> list = new ArrayList<City>();

list.add(city1);
list.add(city2);
list.add(city3);
Map<String, Object> docData = new HashMap<>();
docData.put("modalExample", list);
db.collection("data").document("one")
        .set(docData)
        .addOnSuccessListener(new OnSuccessListener<Void>() {
            @Override
            public void onSuccess(Void aVoid) {
                Log.d(TAG, "DocumentSnapshot successfully written!");
            }
        })
        .addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Log.w(TAG, "Error writing document", e);
            }
        });

【讨论】：