Why does my non-nullable navigation property have a nullable backing field?

[gojanpaolo]

I created the following class:

class Post
{
    public Blog Blog { get; set; }
}

but the backing field in the database is BlogId (FK, int, null) instead of not null. I have enabled nullable reference type in my project. Is there anything else I should configure?

Thank you.

---

Document Details

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• ID: 93c3721a-da23-d9ea-a054-9d786d2ff4d2
• Version Independent ID: 6d3b0f96-6642-75e5-93c8-02c23f142ac4
• Content: Working with nullable reference types - EF Core
• Content Source: entity-framework/core/miscellaneous/nullable-reference-types.md
• Product: entity-framework
• Technology: entity-framework-core
• GitHub Login: @roji
• Microsoft Alias: avickers

[ajcvickers]

Note for triage: I am able to reproduce this.

#nullable enable

public class Blog
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class Post
{
    public int Id { get; set; }
    public string Content { get; set; }

    public Blog Blog { get; set; }
}

public class SomeDbContext : DbContext
{
    private static ILoggerFactory ContextLoggerFactory
        => LoggerFactory.Create(b => b.AddConsole().SetMinimumLevel(LogLevel.Information));

    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseSqlServer(Your.ConnectionString)
            .UseLoggerFactory(ContextLoggerFactory)
            .EnableSensitiveDataLogging();
}

public class Program
{
    public static void Main()
    {
        using (var context = new SomeDbContext())
        {
            context.Database.EnsureDeleted();
            context.Database.EnsureCreated();
        }
    }
}

      CREATE TABLE [Blogs] (
          [Id] int NOT NULL IDENTITY,
          [Name] nvarchar(max) NOT NULL,
          CONSTRAINT [PK_Blogs] PRIMARY KEY ([Id])
      );

      CREATE TABLE [Posts] (
          [Id] int NOT NULL IDENTITY,
          [Content] nvarchar(max) NOT NULL,
          [BlogId] int NULL,
          CONSTRAINT [PK_Posts] PRIMARY KEY ([Id]),
          CONSTRAINT [FK_Posts_Blogs_BlogId] FOREIGN KEY ([BlogId]) REFERENCES [Blogs] ([Id]) ON DELETE NO ACTION
      );

[ajcvickers]

Notes for triage:

• Putting [Required] on the navigation doesn't help
• Adding an inverse navigation does