[英]How to add values to Firebase Firestore without overwriting?
I have two Activities, I am adding data to Firestore from these two activities individually. 我有两个活动,我正在分别从这两个活动向Firestore添加数据。 But, whenever I add second activity data to Firestore, it is overwriting the first activity data.
但是,每当我向Firestore添加第二个活动数据时,它都会覆盖第一个活动数据。 I used below code in the two activities:
我在以下两个活动中使用了以下代码:
firebaseFirestore.collection("Users").document(user_id).set(data)
How to stop overwriting? 如何停止覆盖? I want to save both Activities data in the same
user_id
. 我想将两个活动数据保存在同一个
user_id
。
There are two ways in which you can achieve this. 有两种方法可以实现这一目标。 First one would be to use a
Map
: 首先是使用
Map
:
Map<String, Object> map = new HashMap<>();
map.put("yourProperty", "yourValue");
firebaseFirestore.collection("Users").document(user_id).update(map);
As you can see, I have used update()
method instead of set()
method. 如您所见,我使用了
update()
方法而不是set()
方法。
The second approach would be to use an object of your model class like this: 第二种方法是使用模型类的对象,如下所示:
YourModelClass yourModelClass = new YourModelClass();
yourModelClass.setProperty("yourValue");
firebaseFirestore.collection("Users").document(user_id)
.set(yourModelClass, SetOptions.mergeFields("yourProperty"));
As you can see, I have used the set()
method but I have passed as the second argument SetOptions.mergeFields("yourProperty")
, which means that we do an update only on a specific field. 正如您所看到的,我使用了
set()
方法但是我已经作为第二个参数传递了SetOptions.mergeFields("yourProperty")
,这意味着我们只对特定字段进行更新。
I suggest you to add one more document or collection that it will be able to store more just one data values for single user. 我建议你再添加一个文档或集合,它可以为单个用户存储更多的数据值。
You can create a document references for both activities: 您可以为这两个活动创建文档引用:
firebaseFirestore.collection("Users").document(user_id+"/acitivity1").set(data);
//and
firebaseFirestore.collection("Users").document(user_id+"/acitivity2").set(data);
Or you can create a sub-collection for it: 或者您可以为它创建一个子集合:
firebaseFirestore.collection("Users").document(user_id)
.collection("Activities").document("acitivity1").set(data);
//and
firebaseFirestore.collection("Users").document(user_id)
.collection("Activities").document("acitivity2").set(data);
If you know that the user document allready exists in firestore then you should use 如果您知道用户文档已经存在于firestore中,那么您应该使用
firebaseFirestore.collection("Users").document(user_id).update(data)
If you don't know if the document exists then you can use 如果您不知道文档是否存在,那么您可以使用
firebaseFirestore.collection("Users").document(user_id).set(data, {merge:true})
This performs a deep merge of the data 这将执行数据的深度合并
Alternatively you can do it by using subcollections 或者,您可以使用子集合来完成
As per the documentation, you could use as a second parameter {merge:true}
, in my experience the problem usually is in the fact that you are trying to store different data but with the same key. 根据文档,您可以使用第二个参数
{merge:true}
,根据我的经验,问题通常在于您尝试使用相同的密钥存储不同的数据。
Even using {merge: true}
will always update the current key with the value you are passing in. 即使使用
{merge: true}
也将始终使用您传入的值更新当前键。
Merge:true Works only if the key does not exist already. Merge:true仅在密钥不存在时才起作用。 I believe every key in a document must be unique.
我相信文档中的每个键都必须是唯一的。
To test it try to pass(keeping {merge: true}
as the second parameter) data with a different key, it will merge to existing. 为了测试它,尝试使用不同的密钥传递(使用
{merge: true}
作为第二个参数)数据,它将合并到现有数据。
Try this for a direct update 试试这个直接更新
db.collection('cities').doc('restaurants').update({ rating:"3.2" });
Only the field rating is going to change, the rest of the fields will remain the same. 只有现场评级会发生变化,其余字段将保持不变。
Lets say you have 3 fields, and want to change only 2 of them, you can also do this in a different way 假设您有3个字段,并且只想更改其中的2个字段,您也可以以不同的方式执行此操作
// You get the document 'restaurants' and then do the below
db.collection('cities').doc('restaurants').get().then((doc) => {
// Get the rating field string, parse it to a float, remove 0.4 from it and
// set it to a tmp variable
var tmpRating = parseFloat(doc.data()['rating']) - 0.4;
// Get the array of strings field 'menu' and set it to a tmp variable
var tmpMenu = doc.data()['menu'];
// Push 'spaghetti' string to the tmp array of strings( Can also put an
// adapting string variable instead of a specific string like 'spaghetti'
tmpMenu.push('spaghetti');
// Update only the specific fields 'rating' and 'menu' and keep the rest unchanged.
db.collection('cities').doc(doc.id).update({
rating: toString(tmpRating), // Don't forget to separate them by commas
menu: tmpMenu
});
});
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