添加项目文件。

Entities/Contracts/SubmissionDetail.cs

@@ -0,0 +1,66 @@
+using Microsoft.EntityFrameworkCore;
+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("submission_details")]
+	public class SubmissionDetail
+	{
+		[Key]
+		[Column("id")]
+		public Guid Id { get; set; }
+
+		[Required]
+		[Column("submission_id")]
+		[ForeignKey("Submission")]
+		public Guid SubmissionId { get; set; }
+
+		[Required]
+		[Column("student_id")]
+		[ForeignKey("User")]
+		public Guid StudentId { get; set; }
+
+		[Required]
+		[Column("assignment_question_id")]
+		[ForeignKey("AssignmentQuestion")]
+		public Guid AssignmentQuestionId { get; set; }
+
+		[Column("student_answer")]
+		public string StudentAnswer { get; set; }
+
+		[Column("is_correct")]
+		public bool? IsCorrect { get; set; }
+
+		[Column("points_awarded")]
+		[Precision(5, 2)]
+		public decimal? PointsAwarded { get; set; }
+
+		[Column("teacher_feedback")]
+		public string TeacherFeedback { 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 Submission Submission { get; set; }
+		public User User { get; set; }
+		public AssignmentQuestion AssignmentQuestion { get; set; }
+
+		public SubmissionDetail()
+		{
+			Id = Guid.NewGuid();
+		}
+	}
+}