Normal•12mo ago

Must all RealtimeViews be instantiated at runtime?

Is it not possible to have a RealtimeView in the scene? Do all RealtimeViews need to be instantiated at runtime? I'm getting this error for RealtimeViews that are already in the scene before runtime:

RealtimeView model is null. Was this view instantiated with GameObject.Instantiate instead of Realtime.Instantiate? Make sure you're passing a prefab name and not a prefab reference to avoid accidentally calling GameObject.Instantiate().
UnityEngine.Debug:LogError (object,UnityEngine.Object)

RealtimeView model is null. Was this view instantiated with GameObject.Instantiate instead of Realtime.Instantiate? Make sure you're passing a prefab name and not a prefab reference to avoid accidentally calling GameObject.Instantiate().
UnityEngine.Debug:LogError (object,UnityEngine.Object)

kapa.ai•1/7/25, 4:13 PM

Hi @Harper. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base.

kapa.ai•1/7/25, 4:13 PM

----------------------
No, not all RealtimeViews must be instantiated at runtime. It is possible and common to have RealtimeViews in the scene before runtime. The error message you're seeing is not related to having RealtimeViews in the scene, but rather to how they are being initialized or accessed.

According to the Realtime > RealtimeView documentation, RealtimeViews can exist in the scene, and there's even a specific property called "Scene View UUID" for RealtimeViews that are in the scene:

"The Scene View UUID property will only appear on RealtimeViews that are in the scene. This is a globally unique identifier that is used to synchronize this view's model in the datastore."

The error you're seeing suggests that the RealtimeView's model is null when you're trying to access it. This can happen if you're trying to access the model too early in the lifecycle of the RealtimeView. For scene RealtimeViews, there's a specific initialization process:

and run, and RealtimeView registers with Realtime.
Realtime creates an empty model for every view and component.
When Realtime connects to a room, it either inserts the model into the datastore (if it's new) or populates it with existing state from the server.
becomes true and fires.

As mentioned in the Realtime > Common Questions documentation:

"If you're dealing with a RealtimeView that exists in a scene file, you'll need to wait until , or the event has fired."

kapa.ai•1/7/25, 4:13 PM

To resolve your issue, make sure you're not trying to access the RealtimeView's model before Realtime has connected to the room. You can either check or use the event to ensure you're accessing the model at the right time.

Here's an example of how you might structure your code:

By following this approach, you should be able to use RealtimeViews that are already in your scene without encountering the null model error.
----------------------
Note: you can ask me a follow up question by @ mentioning me again

----------------------

kapa.ai•1/7/25, 4:13 PM

@276154194606424064 Kapa.ai is still learning and improving, please let me know how I did by reacting below.

HarperOP•1/7/25, 4:16 PM

Understood, got it

Mechabit•1/7/25, 4:17 PM

that just means you're accessing the model before connection was complete or you're switching scenes in the middle of connection or similar

HarperOP•1/7/25, 4:18 PM

Yeah that makes since - I think this is happening in my update loop. So, I should wait for the connection to finish before proceeding with update.

HHarper Is it not possible to have a RealtimeView in the scene? Do all RealtimeViews nee...

HarperOP•1/7/25, 4:40 PM

A stack trace for this error would be really useful...

HarperOP•1/7/25, 4:41 PM

@kapa.ai I have updated my code and still receive the same errror.

kapa.ai•1/7/25, 4:41 PM

Let me check the knowledge base for you again. One moment!

kapa.ai•1/7/25, 4:41 PM

----------------------
Thank you for providing your updated code. It seems you're on the right track, but there might still be an issue with how you're accessing the RealtimeView's model. Let's take a closer look at the problem and how to resolve it.

The error you're seeing suggests that the RealtimeView's model is still null when you're trying to access it. This can happen if you're interacting with the RealtimeView before it's fully initialized, even if you're waiting for the room connection.

According to the Realtime > Common Questions documentation, there's a specific order of operations for scene RealtimeViews:

and run, and RealtimeView registers with Realtime.
Realtime creates an empty model for every view and component and sets the model on each, triggering an call.
When Realtime connects to a room, if an object in the scene doesn't exist, its model is inserted into the datastore. If the object already exists, Realtime creates a new RealtimeModel, populates it with the state from the server, and replaces the model again, triggering another call.
becomes true and fires.

To ensure you're interacting with the RealtimeView only after its model is fully initialized, you should use the method in your RealtimeComponent. Here's an example of how you might structure your code:

```csharp
public class MyRealtimeComponent : RealtimeComponent<MyModelType>
{
private bool isModelReady = false;

private void Start()
{
Realtime realtime = FindObjectOfType<Realtime>();
realtime.didConnectToRoom += (Realtime r) => isConnected = true;
}

kapa.ai•1/7/25, 4:42 PM

protected override void OnRealtimeModelReplaced(MyModelType previousModel, MyModelType currentModel)
{
if (currentModel != null)
{
isModelReady = true;
// Initialize your component with the new model here
}
}

private void Update()
{
if (!isConnected || !isModelReady) return;
// Rest of update code ...
}
}
isModelReadyOnRealtimeModelReplaced()Update()isConnectedisModelReady` before proceeding with any model interactions.

This approach ensures that you're only interacting with the RealtimeView's model after both the room connection is established and the model is properly initialized.

If you're still encountering issues after implementing these changes, it might be helpful to review the Realtime > RealtimeComponent documentation for more detailed information on the lifecycle and proper usage of RealtimeComponents.
----------------------
Note: you can ask me a follow up question by @ mentioning me again

----------------------

kapa.ai•1/7/25, 4:42 PM

@276154194606424064 Kapa.ai is still learning and improving, please let me know how I did by reacting below.

HarperOP•1/7/25, 4:43 PM

@kapa.ai so the connection to realtime and the connection to the model happen at different times?

kapa.ai•1/7/25, 4:43 PM

Let me check the knowledge base for you again. One moment!

kapa.ai•1/7/25, 4:43 PM

----------------------
Yes, you're correct. The connection to Realtime and the initialization of the RealtimeView's model happen at different times, and it's important to understand this sequence to properly work with Normcore.

According to the Realtime > Common Questions documentation, the process for scene RealtimeViews follows this order:

First, and methods run, and the RealtimeView registers with Realtime.
Then, Realtime creates an empty model for every view and component, and sets these models, triggering an initial call.
When Realtime actually connects to a room, it either inserts new models into the datastore or populates existing ones with state from the server. This triggers another call.
Finally, becomes true, and the event fires.

This sequence means that:

The connection to Realtime (step 4) happens after the initial model creation (step 2).
The model might be replaced or updated when the actual room connection is established (step 3).

That's why it's recommended to use both the event and the method to ensure you're working with a fully initialized and up-to-date model. The event tells you when you're connected to the room, while informs you when your model is ready or has been updated with the latest data from the server.

This separation allows Normcore to handle various scenarios, such as reconnecting to rooms or dealing with network interruptions, while ensuring that your components always have the most up-to-date data.
----------------------
Note: you can ask me a follow up question by @ mentioning me again

----------------------

kapa.ai•1/7/25, 4:43 PM

@276154194606424064 Kapa.ai is still learning and improving, please let me know how I did by reacting below.

HarperOP•1/7/25, 4:51 PM

@kapa.ai So it can be assumed that when connected the model is loaded?

kapa.ai•1/7/25, 4:51 PM

Let me check the knowledge base for you again. One moment!

kapa.ai•1/7/25, 4:51 PM

----------------------
While it might seem logical to assume that the model is loaded when the connection is established, it's not always safe to make that assumption. Let's clarify this based on the information from the Normcore documentation.

According to the Realtime > Common Questions documentation, the sequence of events for scene RealtimeViews is as follows:

and run, and RealtimeView registers with Realtime.
Realtime creates an empty model for every view and component and sets the model on each, triggering an call.
When Realtime connects to a room, if an object in the scene doesn't exist, its model is inserted into the datastore. If the object already exists, Realtime creates a new RealtimeModel, populates it with the state from the server, and replaces the model again, triggering another call.
becomes true and fires.

This sequence indicates that while the model is created before the connection is established, it might be replaced or updated with data from the server after the connection. Therefore, it's not entirely safe to assume that the model is fully loaded and up-to-date when fires.

For the most reliable approach, it's recommended to use both the event and the method. This ensures that you're working with a fully initialized and up-to-date model.

Here's a safer way to structure your code:

```csharp
public class MyRealtimeComponent : RealtimeComponent<MyModelType>
{
private bool isConnected = false;
private bool isModelReady = false;

kapa.ai•1/7/25, 4:51 PM

private void Start()
{
Realtime realtime = FindObjectOfType<Realtime>();
realtime.didConnectToRoom += (Realtime r) => isConnected = true;
}

protected override void OnRealtimeModelReplaced(MyModelType previousModel, MyModelType currentModel)
{
if (currentModel != null)
{
isModelReady = true;
// Initialize your component with the new model here
}
}

private void Update()
{
if (!isConnected || !isModelReady) return;
// Rest of update code ...
}
}
```

This approach ensures that you're only interacting with the RealtimeView's model after both the room connection is established and the model is properly initialized and up-to-date.
----------------------
Note: you can ask me a follow up question by @ mentioning me again

----------------------

kapa.ai•1/7/25, 4:51 PM

@276154194606424064 Kapa.ai is still learning and improving, please let me know how I did by reacting below.

maxweisel•1/7/25, 4:51 PM

@Harper Scene RealtimeViews connect to Realtime in Start() (it's the earliest we can do it). They don't get a model until you connect to the room. You'll want to subscribe to Realtime.didConnectToRoom or check for Realtime.connected == true

maxweisel•1/7/25, 4:53 PM

more info here:
https://docs.normcore.io/realtime/realtimecomponent#using-views-and-components-in-a-scene

https://docs.normcore.io/realtime/common-questions#why-would-a-realtimecomponents-model-remain-null

HarperOP•1/7/25, 4:53 PM

@Max That's what I'm doing but still finding that I'm getting an error... I subscribe to a didChange function in OnRealtimeModelReplaced and then access the model in the subscribed function. Could the symptom be there?

maxweisel•1/7/25, 4:54 PM

hmm, that should work, although generally I recommend subscribing in Awake() on a component in the scene

maxweisel•1/7/25, 4:54 PM

this is inside of OnRealtimeModelReplaced within a component on the same game object for the view in the scene?

HarperOP•1/7/25, 4:55 PM

Yes

maxweisel•1/7/25, 4:55 PM

or are you waiting for a prefab to instantiate, then subscribing to Realtime.onDidConnect, and then using that to operate on a view in the scene?

maxweisel•1/7/25, 4:55 PM

ok that's really strange. I'd have to see the code then. afaik there's no way for didConnectToRoom to run before the model is set, and the model is being set because OnRealtimeModelReplaced is being called

HarperOP•1/7/25, 5:00 PM

@Max here's my file. I'm almost certain I'm just overlooking something so I apologize if the solution is obvious! For context this is a controller for a door that swings open and close.

P.S. I have no worries if my model is empty when it is first accessed. A few milliseconds of not being able to use doors is no problem.

Door.cs4.49KB

HarperOP•1/7/25, 5:01 PM

Also, I'm on version 2.9.5

HarperOP•1/7/25, 5:01 PM

Have not updated in a while

HarperOP•1/7/25, 5:30 PM

My breakpoints don't seem to be triggering in OnRealtimeModelReplaced. I assume it's not on the main thread?

maxweisel•1/7/25, 5:31 PM

I can dive in a little later but all callbacks are on the main thread

HarperOP•1/7/25, 5:31 PM

Oh you know what

HarperOP•1/7/25, 5:31 PM

I think I've found the problem

maxweisel•1/7/25, 5:31 PM

what was it?

HarperOP•1/7/25, 5:33 PM

Scratch that never mind! Problem still ever-present.

HarperOP•1/7/25, 5:34 PM

Weird that OnRealtimeModelReplaced is never called though.

maxweisel•1/7/25, 5:35 PM

your class looks good at first glance

maxweisel•1/7/25, 5:35 PM

if you add a debug log instead of a breakpoint is it hit?

maxweisel•1/7/25, 5:35 PM

also how was your didConnectToRoom event firing if the method you subscribed in was never getting called?

maxweisel•1/7/25, 5:36 PM

something isn’t adding up

HarperOP•1/7/25, 5:36 PM

I think there may have been a miscommunication earlier regarding what I was doing with didConnectToRoom

HarperOP•1/7/25, 5:37 PM

It is not in the OnRealtimeModelReplaced method

HarperOP•1/7/25, 5:37 PM

It is in awake, and I have also tried putting it in start

Mmaxweisel if you add a debug log instead of a breakpoint is it hit?

HarperOP•1/7/25, 5:37 PM

Negative

HarperOP•1/7/25, 5:45 PM

Not sure if this tells you anything but this is what the inspector looks like

HarperOP•1/7/25, 5:48 PM

Okay. So, I had a suspicion. There are 3 doors, and they are all placed in the scene (not instantiated), but they are also prefabs. I thought: maybe if it's a prefab Normcore assumes it will be instantiated. So, I unpacked all 3 prefabs, and I see no error.