Firestore - 获取子集合的父文档

问题描述

我正在开发一个应用程序，该应用程序使用具有以下层次结构的 Firestore 数据库:parent_collection:父文档:子集:子文档{字符串名称}使用 collectionGroup 我已经能够查询具有特定名称的文档的子集合，但我不知道如何获取 parent_document

I'm working on an app that uses a firestore database with the following hierarchy:parent_collection: parent_document: subcollection: child_document{ string name}using collectionGroup I've been able to query subcollection for documents with a certain name, but I don't know how to get the parent_document

 db.collectionGroup("subcollection").whereEqualTo("name", searchText).get()
                .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<QuerySnapshot> task) {
                        if(task.isSuccessful()){
                          //here I want to get the parent id of all results
                        }
                    }
                });

实现这一目标的最佳方法是什么?

What is the best way to achieve that?

推荐答案

QuerySnapshot 指向多个 QueryDocumentSnapshot 实例.

从 QueryDocumentSnapshot，你可以得到它的集合:

From a QueryDocumentSnapshot, you can get the collection it's from with:

snapshot.getRef().getParent()

然后父 DocumentReference 是:

snapshot.getRef().getParent().getParent()

所以要获得父文档的子集合:

So to get a subscollection of the parent document with:

snapshot.getRef().getParent().getParent().collection("name_of_subcollection")

是的，我同意……这本来可以更具可读性.:)

Yes, I agree... that could've been a bit more readable. :)

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