I created a database in my ASP.NET Web API project, but inserting data causes a problem, because all columns by default are ColName (type, not null). I have StartDate and EndDate. With first insert I would like EndDate to be null. I didn’t find any data attributes to allow null.

As well changing data manually in my ApplicationDBContextModelSnaphot to ‘has default value NULL’ doesn’t do anything neither. How to optionally allow columns to be null?

ConstractionSite.cs:

public class ConstractionSite 
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [MaxLength(50)]
    [Required]
    public string Name { get; set; } = string.Empty;
    public virtual ConstractionStatus Status { get; set; } 

    [ForeignKey("Status")]
    public int StatusId { get; set; }

    public DateOnly StartDate { get; set; }
    public DateOnly EndDate { get; set; } 
} 

ApplicationDbContextModelSnapshot.cs:

  modelBuilder.Entity("WervenProj.Models.ConstractionSite", b =>
  {
      b.Property<int>("Id")
          .ValueGeneratedOnAdd()
          .HasColumnType("int");

      SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));

      b.Property<DateOnly>("EndDate")
          .HasColumnType("date").HasDefaultValue(null);

      b.Property<string>("Name")
          .IsRequired()
          .HasMaxLength(50)
          .HasColumnType("nvarchar(50)");

      b.Property<DateOnly>("StartDate")
          .HasColumnType("date");

      b.Property<int>("StatusId")
          .HasColumnType("int");

      b.HasKey("Id");

      b.HasIndex("StatusId");

      b.ToTable("ConstractionSites", (string)null);
  });

I also manually updated migration file to the property EndDate nullable: true and I ran update-database. Nothing works.

Migration.cs:

migrationBuilder.CreateTable(
    name: "ConstractionSites",
    columns: table => new
    {
        Id = table.Column<int>(type: "int", nullable: false)
                  .Annotation("SqlServer:Identity", "1, 1"),
        Name = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: false),
        StatusId = table.Column<int>(type: "int", nullable:  false),
        StartDate = table.Column<DateOnly>(type: "date", nullable: false),
        EndDate = table.Column<DateOnly>(type: "date", nullable: true)
    },
    constraints: table =>
    {
        table.PrimaryKey("PK_ConstractionSites", x => x.Id);
        table.ForeignKey(
          name: "FK_ConstractionSites_ConstractionStatuses_StatusId",
          column: x => x.StatusId,
          principalTable: "ConstractionStatuses",
          principalColumn: "Id",
          onDelete: ReferentialAction.Cascade);
  });

Any tips? Thank you.

Another question: ConstractionSiteModel has a foreign key related to Status model. When I add with API ‘create new site’ via swagger and add manually ID for StatusId field, it generates new instance in the Status table as well with empty columns, but new a ID key and changes StatusId in ConstractionSites with new generated. Why? Is there other way to create foreign key relation?