EF Core 3.1.4 Navigation property returning null in One-To-One relationship - .net-core

Question

I am having a problem where a navigation property is always returning null in a One-to-One relationship in EF Core 3.1.4.
My models are structured like so:
public class UserCredential
{
public Guid Id { get; set; }
public string Username { get; set; }
public string Password { get; set; }
public byte[] Salt { get; set; }
public bool IsLocked { get; set; }
public bool IsDeleted { get; set; }
public DateTime CreatedDate { get; set; }
public DateTime? ModifiedDate { get; set; }
public DateTime? DeletedDate { get; set; }
public UserProfile UserProfile { get; set; }
}
public class UserProfile
{
public Guid Id { get; set; }
public string FirstName { get; set; }
public string MiddleName { get; set; }
public string LastName { get; set; }
public string Suffix { get; set; }
public bool IsDeleted { get; set; }
public List<Address> Addresses {get;set;}
public DateTime DOB { get; set; }
public DateTime CreatedDate { get; set; }
public DateTime? ModifiedDate { get; set; }
public DateTime? DeletedDate { get; set; }
public Guid UserCredentialId { get; set; }
public UserCredential UserCredential { get; set; }
}
Based off what I understand, that should have been enough for EF Core to infer the One-To-One relationship. But it didnt work so I defined the relationshup in my dbContext like so:
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<UserProfile>(entity =>
{
entity.HasOne(up => up.UserCredential)
.WithOne(uc => uc.UserProfile)
.HasForeignKey<UserProfile>( up => up.UserCredentialId);
});
}
I checked the db and there is a foreign key from UserProfile -> UserCredentials defined in the table. Likewise both tables have Id as a primary key.
If I post data to a "addUser" endpoint it will be added correctly in the db.
{
"username": "test3",
"password": "password123",
"UserProfile":{
"FirstName": "John",
"LastName": "Doe"
}
}
Db Screenshot
However "UserProfile" in my model is always null.
System.NullReferenceException: 'Object reference not set to an
instance of an object.'
IronCarp.Identity.Models.UserCredential.UserProfile.get returned null.
I'm using a repository to interact with the db and the method that is returning my data/model seems simple enough.
private async Task<UserCredential> GetUserCredentials(string username)
{
return await context.UserCredentials.Where(u => u.Username == username).FirstOrDefaultAsync();
}
Any help is appreciated, I am not sure what I am missing, thanks!

Answer 1

try to include navigation property in linkq, try something like this:
private async Task<UserCredential> GetUserCredentials(string username)
{
return await context.UserCredentials.Include(x => x.UserProfile).Where(u => u.Username == username).FirstOrDefaultAsync();
}

Answer 2

For me this issue was happening intermittently in my integration tests.
It turned out because I was mistakenly registering the EF Core DbContext as Transient and not Scoped:
Services.AddDbContext<SubscriptionsContext>(
options => options.UseNpgsql(appConfig.DatabaseConnectionString,
optionsBuilder => optionsBuilder.EnableRetryOnFailure(3)), ServiceLifetime.Transient);
Should be:
Services.AddDbContext<SubscriptionsContext>(
options => options.UseNpgsql(appConfig.DatabaseConnectionString,
optionsBuilder => optionsBuilder.EnableRetryOnFailure(3)), ServiceLifetime.Scoped);
If you look at the default parameter on the AddDbContext() extension method, it's always Scoped: