Firestore-获取子集合的父文档 [英] Firestore - get the parent document of a subcollection

问题描述

我正在使用一个使用以下层次结构的Firestore数据库的应用程序: parent_collection: parent_document: 子集合: child_document { 字符串名称} 使用collectionGroup，我已经能够查询子集合中具有特定名称的文档，但是我不知道如何获取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
                        }
                    }
                });

实现此目标的最佳方法是什么?

What is the best way to achieve that?

推荐答案

QuerySnapshot指向许多QueryDocumentSnapshot实例.

通过QueryDocumentSnapshot，您可以通过以下方式获取其来源:

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

snapshot.getRef().getParent()

然后父级DocumentReference是:

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

因此要获取父文档的子集，请执行以下操作:

So to get a subscollection of the parent document with:

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

是的，我同意...这本来应该更具可读性. :)

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

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