添加项目文件。

Entities/Contracts/AssignmentGroup.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations.Schema;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Entities.Contracts
+{
+	[Table("assignment_group")]
+	public class AssignmentGroup
+	{
+		[Key]
+		[Column("id")]
+		public Guid Id { get; set; }
+
+		[Required]
+		[Column("assignment")]
+		[ForeignKey("Assignment")]
+		public Guid AssignmentId { get; set; }
+
+		[Required]
+		[Column("title")]
+		[MaxLength(65535)] 
+		public string Title { get; set; }
+
+		[Column("descript")]
+		[MaxLength(65535)] 
+		public string Descript { get; set; }
+
+
+		[Column("total_points")]
+		public decimal? TotalPoints { get; set; }
+
+		[Column("number")]
+		public byte Number { get; set; }
+
+		[Column("parent_group")]
+		public Guid? ParentGroup { get; set; }
+
+		[Column("deleted")]
+		public bool IsDeleted { get; set; }
+
+		// Navigation Properties
+		public Assignment Assignment { get; set; }
+		public AssignmentGroup ParentAssignmentGroup { get; set;}
+		public ICollection<AssignmentGroup> ChildAssignmentGroups { get; set; }
+		public ICollection<AssignmentQuestion> AssignmentQuestions { get; set; }
+
+
+		public AssignmentGroup()
+		{
+			Id = Guid.NewGuid();
+			ChildAssignmentGroups = new HashSet<AssignmentGroup>();
+			AssignmentQuestions = new HashSet<AssignmentQuestion>();
+		}
+	}
+}