添加项目文件。

Entities/Contracts/Assignment.cs

@@ -0,0 +1,63 @@
+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("assignments")]
+	public class Assignment
+	{
+		[Key]
+		[Column("id")]
+		public Guid Id { get; set; }
+
+		[Required]
+		[Column("title")]
+		[StringLength(255)]
+		public string Title { get; set; }
+
+		[Column("description")]
+		public string Description { get; set; }
+
+		[Required]
+		[Column("due_date")]
+		public DateTime DueDate { get; set; }
+
+		[Column("total_points")]
+		public decimal? TotalPoints { get; set; }
+
+		[Column("created_by")]
+		[ForeignKey("Creator")]
+		public Guid CreatedBy { 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 User Creator { get; set; }
+		public ICollection<AssignmentClass> AssignmentClasses { get; set; }
+		public ICollection<AssignmentGroup> AssignmentGroups { get; set; }
+		public ICollection<AssignmentAttachment> AssignmentAttachments { get; set; }
+		public ICollection<Submission> Submissions { get; set; }
+
+		public Assignment()
+		{
+			Id = Guid.NewGuid();
+
+			Submissions = new HashSet<Submission>();
+			AssignmentGroups = new HashSet<AssignmentGroup>();
+			AssignmentClasses = new HashSet<AssignmentClass>();
+			AssignmentAttachments = new HashSet<AssignmentAttachment>();
+		}
+	}
+}