Firebase文档中文档的Firestore子集合 [英] Firebase Firestore subcollection of documents from document

问题描述

在集合的SnapshotListener中，我正在使用以下命令循环浏览这些文档:

In my collection's SnapshotListener, I have am looping through the documents with:

for (DocumentChange doc : queryDocumentSnapshots.getDocumentChanges()) {
    if (doc.getType() == DocumentChange.Type.ADDED) {
        String somestr = doc.getDocument.getString("someField");
        // retrieve collection here
    }
}

在for循环的每个文档中，我们将其称为 doc ，Cloud Firestore上还有另一个文档集合.我想在 doc 内的子集合中检索所有文档(每个文档都只有一个String字段).我能够执行 doc.getDocument 来获取 doc 本身，我正在使用它来获取字符串字段，但是我不知道如何获取文档在其子集合中.

And within each document in the for loop, let's call it doc, I have another collection of documents on Cloud Firestore. I would like to retrieve all documents (each of which just has a single String field) within the subcollection inside doc. I'm able to do a doc.getDocument to get doc itself, which I am using to get a string field, but I don't know how to get the documents in its subcollection.

推荐答案

您首先使用以下方法获得子集合:

You first get the subcollection with:

doc.getDocument().getReference().getCollection("subcollection")

然后，您可以像以前一样将文档保存到其中(或如本文档部分).

And then you get the documents in there like you did before (or as shown in this documentation section).

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