Firestore可以使用一个查询更新多个符合条件的文档吗? [英] Can Firestore update multiple documents matching a condition, using one query?

问题描述

换句话说，我正在尝试找出SQL中与之等效的Firestore:

In other words, I'm trying to figure out what is the Firestore equivalent to this in SQL:

UPDATE table SET field = 'foo' WHERE <condition>`

是的，我正在问如何更新多个文档，一次，但与链接的问题，我特别想问一下如何做到这一点，而无需将任何内容读入内存，因为当您只想在所有与a匹配的文档上设置标记时，就无需这样做条件.

Yes, I am asking how to update multiple documents, at once, but unlike the linked questions, I'm specifically asking how to do this in one shot, without reading anything into memory, because there's no need to do so when all you want is to set a flag on all documents matching a condition.

db.collection('table')
  .where(...condition...)
  .update({
    field: 'foo',
  });

是我期望的工作， CollectionReference 没有.update方法.

is what I expected to work, CollectionReference doesn't have an .update method.

事务和批处理写入文档中提到了事务和批处理写入.进行事务处理是因为事务包含任意数量的 get()操作，后跟任意数量的写操作"

The Transactions and Batched Writes documentation mentions transactions and batched writes. Transactions are out because "A transaction consists of any number of get() operations followed by any number of write operations" Batched writes are also not a solution because they work document-by-document.

使用 MongoDB ，这将是

db.table.update(
  { /* where clause */ },
  { $set: { field: 'foo' } }
)

那么，Firestore是否可以通过一个查询(SQL数据库或MongoDB的工作方式)来更新多个文档，即无需为每个文档往返客户端?如果没有，如何有效地做到这一点?

So, can Firestore update multiple documents with one query, the way SQL database or MongoDB work, i.e. without requiring a round-trip to the client for each document? If not, how can this be done efficiently?

推荐答案

在Cloud Firestore中更新文档需要知道其ID. Cloud Firestore不支持等效的SQL更新查询.

Updating a document in Cloud Firestore requires knowings its ID. Cloud Firestore does not support the equivalent of SQL's update queries.

您将始终必须分两个步骤进行操作:

You will always have to do this in two steps:

1. 根据您的条件运行查询以确定文档ID
2. 使用单个更新或一个或多个批量写入.

请注意，您仅需要步骤1中的文档ID.因此，您可以运行仅返回ID的查询.在客户端SDK中这是不可能的，但是可以通过REST API和Admin SDK完成，如下所示:

Note that you only need the document ID from step 1. So you could run a query that only returns the IDs. This is not possible in the client-side SDKs, but can be done through the REST API and Admin SDKs as shown here: How to get a list of document IDs in a collection Cloud Firestore?

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