添加项目文件。

Entities/Contracts/Class.cs

@@ -0,0 +1,55 @@
+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("classes")]
+	public class Class
+	{
+		[Key]
+		[Column("id")]
+		public Guid Id { get; set; }
+
+		[Column("grade")]
+		public byte Grade { get; set; }
+
+		[Column("class")]
+		public byte Number { get; set; }
+
+		[Column("description")]
+		public string Description { get; set; }
+
+		[Column("head_teacher_id")]
+		public Guid? HeadTeacherId { get; set; }
+		public User HeadTeacher { get; set; }
+
+		[Column("created_at")]
+		public DateTime CreatedAt { get; set; }
+
+		[Column("updated_at")]
+		public DateTime UpdatedAt { get; set; }
+
+		[Column("deleted")]
+		public bool IsDeleted { get; set; }
+
+		// Navigation Properties
+		public ICollection<ClassTeacher> ClassTeachers { get; set; }
+		public ICollection<ClassStudent> ClassStudents { get; set; }
+		public ICollection<AssignmentClass> AssignmentClasses { get; set; }
+
+		public Class()
+		{
+			Id = Guid.NewGuid();
+			Grade = 0;
+			Number = 0;
+			ClassStudents = new HashSet<ClassStudent>();
+			ClassTeachers = new HashSet<ClassTeacher>();
+			AssignmentClasses = new HashSet<AssignmentClass>();
+		}
+	}
+}