swift - Firestore : How i can read subcollection data with documentID?

Question

我如何才能只阅读当前用户的评论？对于“我自己的评论”页面。我的代码已运行，但如果(其中字段:currentuid)不存在则不打印(“无数据”)。只打印 ("documents.data()")

    let db = Firestore.firestore()
    db.collection("tweets").getDocuments { (snapshot, error) in
        for document in snapshot!.documents {
            self.db.collection("tweets").document(document.documentID).collection("comments").whereField("uid", isEqualTo: self.uid).getDocuments(completion: { (snapshot2, error2) in
                for document2 in snapshot2!.documents {
                    print("\(document2.documentID) -> \(document2.data())")
                }
            })
        }
    }

Answer 1

我想你正在寻找这个:

let db = Firestore.firestore()
db.collection("tweets").getDocuments { (snapshot, error) in
    for document in snapshot!.documents {
        self.db.collection("tweets").document(document.documentID).collection("comments")
          .whereField("uid", isEqualTo: self.uid).getDocuments(completion: { (snapshot2, error2) in
            if let err = err {
                print("Error getting documents: \(err)")
            } else {
                if snapshot2.isEmpty {
                    print("No comments from \(self.uid) found")
                } else {
                    for document2 in snapshot2!.documents {
                        print("\(document2.documentID) -> \(document2.data())")
                    }
                }
            }
        })
    }
}

请注意，集合组查询的工作正在进行中，这将允许您在所有名为 comments 的集合中使用单个查询执行上述操作。