MongoDB Realm cannot update user embedded object in Swift

Question

I'm trying to add to an embedded "Conversation" object within my user collection (for a chat app) in Mongo Realm. I would like to create a "default" conversation when the user account is created, such that every user should be a member of at least one conversation that they can then add others to.

The app currently updates the user collection via a trigger and function in Realm at the back end using the email / Password authentication process.

My classes are defined in Swift as follows:

@objcMembers class User: Object, ObjectKeyIdentifiable {
    dynamic var _id = UUID().uuidString
    dynamic var partition = "" // "user=_id"
    dynamic var userName = ""
    dynamic var userPreferences: UserPreferences?
    dynamic var lastSeenAt: Date?
    var teams = List<Team>()
    dynamic var presence = "Off-Line"

    var isProfileSet: Bool { !(userPreferences?.isEmpty ?? true) }
    var presenceState: Presence {
        get { return Presence(rawValue: presence) ?? .hidden }
        set { presence = newValue.asString }
    }

    override static func primaryKey() -> String? {
        return "_id"
    }

@objcMembers class Conversation: EmbeddedObject, ObjectKeyIdentifiable {
    dynamic var id = UUID().uuidString
    dynamic var displayName = ""
    dynamic var unreadCount = 0
    var members = List<Member>()
    
}

So my current thinking is that I should code it in Swift as follows which I believe should update the logged in user, but sadly can't get this quite right:

 // Open the default realm
        let realm = try! Realm()
        
        try! realm.write {
            let conversation = Conversation()
            conversation.displayName = "My Conversation"
            conversation.unreadCount = 0
        
            var user = app.currentUser
            let userID = user.id
            
            let thisUser = User(_id: userID)
            realm.add(user)
        }

Can anyone please spot where I'm going wrong in my code?

Hours spent on Google and I'm missing something really obvious! I have a fair bit of .NET experience and SQL but struggling to convert to the new world!

I'm a noob when it comes to NoSQL databases and SwiftUI and trying to find my way looking at a lot of Google examples. My example us based on the tutorial by Andrew Morgan https://developer.mongodb.com/how-to/building-a-mobile-chat-app-using-realm-new-way/

The question is a bit unclear; what do you mean by a *default conversation*? Theres nothing else in the question that references so.. what are you asking? Why are you giving an embedded object an id? Can you clarify? — Jay, Jun 02 '21 at 18:22
There's no way for us to know if that `id` is needed or not. You have it there so does it have a function? Also, we still don't know what's being asked or how a *conversation* fits into the question or the code. Remember - only you know your code so questions need to be clear, specific and brief for us to be able to help. Please take a moment and review [How do I ask a good question?](https://stackoverflow.com/help/how-to-ask) for some tips on asking. — Jay, Jun 02 '21 at 18:43
Have edited it Jay which I hope is clearer - thanks for your input — David Carney, Jun 02 '21 at 21:28
The code is a little non-sensical at the moment, perhaps just an oversight. Your creating a conversation with `let conversation = Conversation()` but then nothing else is done with it. Also, we don't know what the Conversation model looks like either. A Teams properties are being populated `team.displayName = "My Conversation"` but there is no team object. In the Realm write, you're creating a user with a duplicate user id, which doesn't sound like a good idea. There's also a members property `var members = List()`but we don't know what that is. Can you clarify the code? — Jay, Jun 02 '21 at 23:17
Thanks Jay apologies team should have read conversation! Pasted incorrect code in here which I’ve now corrected. List members allows other users to be added to a conversation — David Carney, Jun 03 '21 at 07:10

score 0 · Answer 1 · answered Jun 03 '21 at 18:00

I am a bit unclear on the exact use case here but I think what's being asked is how to initialize an object with default values - in this case, a default conversation, which is an embedded object.

If that's not the question, let me know so I can update.

Starting with User object

class UserClass: Object {
    @objc dynamic var _id = ObjectId.generate()
    @objc dynamic var name = ""

    let conversationList = List<ConversationClass>()

    convenience init(name: String) {
        self.init()
        self.name = name

        let convo = ConversationClass()
        self.conversationList.append(convo)
    }

    override static func primaryKey() -> String? {
        return "_id"
    }
}

and the EmbeddedObject ConversationClass

class ConversationClass: EmbeddedObject {
    dynamic var displayName = "My Conversation"
    dynamic var unreadCount = 0
    var members = List<MemberClass>()
}

The objective is that when a new user is created, they have a default conversation class added to the conversationList. That's done in the convenience init

So the entire process is like this:

let realm = Realm()
let aUser = UserClass(name: "Leroy")
try! realm.write { 
   realm.add(aUser)
}

Will initialize a new user, set their name to Leroy. It will also initialize a ConversationClass Embedded object and add it to the conversationList.

The ConversationClass object has default values set for displayName and unread count per the question.

MongoDB Realm cannot update user embedded object in Swift

1 Answers1