Get XDB Sitecore.Analytics.Tracking.Contact with Contact Id always returning null value

Question

I am working with XDB to get Contact by Contact-Id using LoadContact method in Sitecore 9 Update 2, but it returns me the null value of contact, The same contact-Id exist in my Shard0 database with facets values. To do the same I am using below code:

public object GetContactCustomFields(Guid contactId)
    {
        try
        {
            var contactManager = Sitecore.Configuration.Factory.CreateObject("tracking/contactManager", true) as Sitecore.Analytics.Tracking.ContactManager;
            var contact = contactManager.LoadContact(contactId, true);
            if (contact == null)
            {
                throw new ContactNotFoundException();
            }
            var customFacet = contact.GetFacet<IFacetModelName>(FacetModelName.DefaultKey);
            return customFacet;
        }
        catch (ContactNotFoundException ex)
        {
            return Request.CreateResponse(HttpStatusCode.NotFound, ex.Message);
        }
    }

Here Contact type is Sitecore.Analytics.Tracking.Contact instead of Sitecore.XConnect.Contact. Because of by using this contact I am trying to get custom facet data and want to display on the experience profile tab.

After updating the code as suggested in answer by @x3mxray, I am getting below error:

Update Code:

[HttpGet]
    public async Task<StickyFormPreOTPInformation> GetContactCustomFields(Guid contactId)
    {
        using (Sitecore.XConnect.Client.XConnectClient client = Sitecore.XConnect.Client.Configuration.SitecoreXConnectClientConfiguration.GetClient())
        {
            try
            {
                Sitecore.XConnect.ContactReference reference = new Sitecore.XConnect.ContactReference(contactId);
                var contactTask = client.GetAsync<Contact>(
                    reference,
                    new Sitecore.XConnect.ContactExpandOptions(StickyFormPreOTPInformation.FACET_NAME)
                );

                var contact = await contactTask;

                if (contact == null)
                {
                    return null;
                }
                var customFacet = contact.GetFacet<IStickyFormPreOTPInformation>(StickyFormPreOTPInformation.FACET_NAME);
                return customFacet;
            }
            catch (Sitecore.XConnect.XdbExecutionException)
            {
                // TODO: catch exception 
            }
        }
        return null;
    }

Error:

Update Code 2: After updating client.GetAsync, Contact from Sitecore.XConnect namespace, getting below error:

Answer 1

You should extract Contact from XConnect (Shards databases related to xDb).

public async Task<FacetModelName> GetContactCustomFields(Guid contactId)
{
    using (XConnectClient client = Sitecore.XConnect.Client.Configuration.SitecoreXConnectClientConfiguration.GetClient())
    {
        try
        {
           ContactReference reference = new ContactReference(contactId);
            var contactTask = client.GetAsync<Contact>(
                reference,
                new ContactExpandOptions(FacetModelName.DefaultKey)
            );

            var contact = await contactTask;

            if (contact == null)
            {
                return null;
            }

            var customFacet = contact.GetFacet<FacetModelName>(FacetModelName.DefaultKey);
            return customFacet;

        }
        catch (XdbExecutionException ex)
        {
            // TODO: catch exception 
        }
    }

    return null;
}

FacetModelName:

    [Serializable]
    [FacetKey(DefaultFacetKey)]
    public class FacetModelName : Facet
    {
        public const string DefaultFacetKey = "MyFacet";

        public FacetModelName()
        {

        }

        // define needed properties
    }

To make your facet visible for the xConnect and xconnect jobs, you need to build custom model where we register new facet.

public static class XdbCustomModel
    {
        public static XdbModel Model { get; } = BuildModel();

        private static XdbModel BuildModel()
        {
            XdbModelBuilder modelBuilder = new XdbModelBuilder("CustomModel", new XdbModelVersion(1, 0));

            modelBuilder.ReferenceModel(Sitecore.XConnect.Collection.Model.CollectionModel.Model);
            modelBuilder.DefineFacet<Contact, FacetModelName>(FacetModelName.DefaultFacetKey);

            return modelBuilder.BuildModel();
        }
    }

Then you need generate json file:

 var fileName = XdbCustomModel.Model.FullName + ".json";
 var json = XdbModelWriter.Serialize(XdbCustomModel.Model);
 System.IO.File.WriteAllText(fileName, json);

Copy this generated json file to Model folder of xConnect and Model folder of xConnect jobs:

xconnect_instance\App_Data\Models\ xconnect_instance\App_Data\jobs\continuous\ProcessingEngine\App_Data\Models\ xconnect_instance\App_Data\jobs\continuous\AutomationEngine\App_Data\Models\ xconnect_instance\App_Data\jobs\continuous\IndexWorker\App_data\Models\

For more information about custom facets see corresponding section of official sitecore documentation: https://doc.sitecore.com/developers/90/sitecore-experience-platform/en/create-a-custom-facet.html