如何从 firestore 获取完整文档，包括填充的参考数据

Question

I am using Firestore in my Swift project. I would like to get all the reference data inside the document populated when I fetch the list. But currently, I only get the reference Ids.

Here is the sample code that I am using to get the list of conversations

func getConversationByUserId(createdBy: String, completion: @escaping ([Conversation])->()) {
        let conversationRef = DBHelper.shared.database.collection("conversations")
        let createdByRef = DBHelper.shared.database.document("users/\(createdBy)")
        
        conversationRef
            .whereField("members", arrayContains: createdByRef)
            .addSnapshotListener() { (querySnapshot, err) in
                if let err = err {
                    print("Error getting documents: \(err)")
                } else {
                    if querySnapshot!.documents.isEmpty {
                        completion([])
                    } else {
                        var conversations: [Conversation] = []
                        if let snaps = querySnapshot?.documents {
                            for item in snaps {
                                conversations.append(Conversation(snapshot: item))
                            }
                        }
                        completion(conversations)
                    }
                }
            }
    }

Answer 1

Firestore is a NoSQL database, we need to switch our coding mind from SQL database.

I would recommend to either store all related information in one document or you can fetch all needed information with multiple calls.

If you want to simplify the front-end logic, you can consider use Firebase Cloud Function to take over the multiple fetching logic.