How to assign default value to a foreign key using fluent api?

I created two models using fluent api in my dbcontext(ToDo, Category) what I want to achieve is that whenever I create a new ToDo object, the default value for CategoryId is specified as an id for the ‘Default’ category that I successfully created previously, I still need that relationship to be non optional to be able to use cascade deletion, but so that if not specified in a request body, the value of categoryid always assigns to 1.

The issue I’m having now is that when not specifying the categoryid simply gets a null value.
Here are the request and the respond that followed it:
POST to api/todos


    "id": 2,
    "context": "234234",
    "done": false,
    "dueDate": "0001-01-01T00:00:00",
    "category": null
  public class AppDbContext : DbContext
        public DbSet<Category> categories { get; set; }
        public DbSet<ToDo> todos { get; set; }

        public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }

        protected override void OnModelCreating(ModelBuilder builder)

            builder.Entity<ToDo>().HasKey(p => p.Id);
            builder.Entity<ToDo>().Property(p => p.Id).IsRequired().ValueGeneratedOnAdd();
            builder.Entity<ToDo>().Property(p => p.Context).HasMaxLength(50);
            builder.Entity<ToDo>().Property(p => p.Done);
            builder.Entity<ToDo>().Property(p => p.DueDate);
            builder.Entity<ToDo>().Property(p => p.CategoryId).HasDefaultValue(1);

            builder.Entity<Category>().HasKey(p => p.Id);
            builder.Entity<Category>().Property(p => p.Id).IsRequired().ValueGeneratedOnAdd();//.HasValueGenerator<InMemoryIntegerValueGenerator<int>>();
            builder.Entity<Category>().Property(p => p.Name).IsRequired().HasMaxLength(30);
            builder.Entity<Category>().HasMany(p => p.ToDoS).WithOne(p => p.Category).HasForeignKey(p => p.CategoryId);

          Id = 1,
          Name = "Default"




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Method 1

After reviewing the comments and searching the web I can clearly say that the problem really was the usage of inmemorydb , cause after switching to localdb everything works just fine.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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