Create topics

You can use the Annotations package to create new topics and fetch existing topics.

Prerequisites

Before you create a topic, you must first set up a Unity scene with an AnnotationRepository. See Get started for more information.

Create a new topic

To create a new topic, follow these steps:

1. Open the AnnotationBehaviour script you created in Get started.

2. Paste the following code sample into your script. The new CreateTopicExample() method creates a TopicCreation request object and displays information about the created topic. The CreateTopicExample() method is called in the RunExamples() method.

   using System;
   using System.Linq;
   using System.Threading.Tasks;
   using Unity.Cloud.Common;
   using Unity.Cloud.Identity;
   using Unity.Cloud.Annotation.Runtime;
   using UnityEngine;
   
   public class AnnotationBehaviour : MonoBehaviour
   {
       // The annotation repository retrieves, creates, edits, and removes annotations from a scene
       IAnnotationRepository m_AnnotationRepository;
   
       // The id for the scene to initialize the annotation repository with
       static readonly SceneId k_SceneId = new("<enter-id-here>");
   
       // The authenticator responsible for user login
       ICompositeAuthenticator m_CompositeAuthenticator;
       bool m_HasAttemptedLogin;
   
       async Task Start()
       {
           // Register to get notified of the login state after the authenticator has initialized
           m_CompositeAuthenticator = PlatformServices.CompositeAuthenticator;
           m_CompositeAuthenticator.AuthenticationStateChanged += ApplyAuthenticationState;
   
           // Apply the initial state for the authenticator
           ApplyAuthenticationState(m_CompositeAuthenticator.AuthenticationState);
       }
   
       void ApplyAuthenticationState(AuthenticationState newAuthenticationState)
       {
           switch (newAuthenticationState)
           {
               case AuthenticationState.LoggedIn:
                   // If the user is logged in, initialize the repository
                   m_CompositeAuthenticator.AuthenticationStateChanged -= ApplyAuthenticationState;
                   _ = InitializeAnnotationRepository();
                   break;
               case AuthenticationState.LoggedOut:
                   // If the user is logged out, attempt to automatically login
                   // Set a flag to ensure we only attempt an auto-login once
                   if (!m_HasAttemptedLogin)
                   {
                       m_HasAttemptedLogin = true;
                       _ = m_CompositeAuthenticator.LoginAsync();
                   }
                   else
                   {
                       // Unregister if login attempt failed
                       m_CompositeAuthenticator.AuthenticationStateChanged -= ApplyAuthenticationState;
                   }
                   break;
           }
       }
   
       async Task InitializeAnnotationRepository()
       {
           // Gets a scene
           var scene = await PlatformServices.SceneProvider.GetSceneAsync(k_SceneId);
   
           // Create a new AnnotationRepository with the chosen scene
           m_AnnotationRepository = new AnnotationRepository(scene, PlatformServices.ServiceHttpClient, PlatformServices.ServiceHostResolver);
   
           await RunExamples();
       }
   
       async Task RunExamples()
       {
           await CreateTopicExample();
   
           // Logs you out after running the examples
           if (PlatformServices.CompositeAuthenticator.RequiresGUI)
               await PlatformServices.CompositeAuthenticator.LogoutAsync();
       }
   
       async Task CreateTopicExample()
       {
           // Creates a TopicCreation request object using a TopicCreationBuilder and populates it with the necessary fields
           var topicCreationBuilder = new TopicCreationBuilder();
           topicCreationBuilder.SetTitle("A new title");
           topicCreationBuilder.SetDescription("A descriptive description");
   
           // Sends the request to the AnnotationRepository and waits for the result
           var createdTopic = await m_AnnotationRepository.CreateTopicAsync(topicCreationBuilder.GetTopicCreation());
   
           // Outputs the created topic information
           Debug.Log($"Created Topic ID: {createdTopic.Id}, Created Topic Title: {createdTopic.Title}");
   
           // Fetches an existing topic using that existing topic's ID
           var fetchedTopic = await m_AnnotationRepository.GetTopicAsync(createdTopic.Id);
   
           // Outputs the fetched topic information
           Debug.Log($"Fetched Topic ID: {fetchedTopic.Id}, Created Topic Title: {fetchedTopic.Title}");
       }
   }
   

3. Run the scene and check your console to confirm that the new topic was created and fetched.