重构项目结构，移除Assignment相关功能，优化Submission模块

Entities/Contracts/Submission.cs

@@ -17,18 +17,30 @@ namespace Entities.Contracts
 		public Guid Id { get; set; }
 
 		[Required]
-		[Column("assignment_id")]
-		[ForeignKey("Assignment")]
-		public Guid AssignmentId { get; set; }
+		[Column("exam_id")]
+		public Guid ExamId { get; set; }
+		[ForeignKey(nameof(ExamId))]
+		public virtual Exam Exam { get; set; }
 
 		[Required]
 		[Column("student_id")]
-		[ForeignKey("Student")]
 		public Guid StudentId { get; set; }
+		[ForeignKey(nameof(StudentId))]
+		public virtual User Student { get; set; }
+
+		[Column("graded_by")]
+		public Guid? GraderId { get; set; }
+		[ForeignKey(nameof(GraderId))]
+		public virtual User Grader { get; set; }
+
+		[Column("class_id")]
+		public Guid ClassId { get; set; }
+		[ForeignKey(nameof(ClassId))]
+		public virtual Class Class { get; set; }
 
 		[Required]
 		[Column("attempt_number")]
-		public byte AttemptNumber { get; set; }
+		public byte AttemptNumber { get; set; }  // 第几次提交
 
 		[Column("submission_time")]
 		public DateTime SubmissionTime { get; set; }
@@ -39,31 +51,36 @@ namespace Entities.Contracts
 		[Column("overall_feedback")]
 		public string? OverallFeedback { get; set; }
 
-		[Column("graded_by")]
-		[ForeignKey("Grader")]
-		public Guid? GraderId { get; set; }
-
 		[Column("graded_at")]
 		public DateTime? GradedAt { get; set; }
 
-		[Column("deleted")]
-		public bool IsDeleted { get; set; }
-
-		public byte TotalQuesNum { get; set; }
-
-		public byte ErrorQuesNum { get; set; }
-
-		public byte TotalScore { get; set; }
-
 		[Required]
 		[Column("status")]
 		public SubmissionStatus Status { get; set; }
 
+		[Column("deleted")]
+		public bool IsDeleted { get; set; }
 		// Navigation Properties
-		public Assignment Assignment { get; set; }
-		public User Student { get; set; }
-		public User Grader { get; set; }
-		public ICollection<SubmissionDetail> SubmissionDetails { get; set; }
+
+		[NotMapped]
+		public int ErrorCount => SubmissionDetails.Where(sd => sd?.IsCorrect == false && sd.IsCorrect != null).Count();
+
+		[NotMapped]
+		public Dictionary<string, int> ErrorQuestionTypeDistribution => SubmissionDetails
+			.Where(sd => sd?.IsCorrect == false)
+			.GroupBy(sd => sd.ExamQuestion.Type.Name)
+			.ToDictionary(g => g.Key, g => g.Count());
+
+		[NotMapped]
+		public Dictionary<string, int> ErrorQuestionLessonDistribution => SubmissionDetails
+			.Where(sd => sd?.IsCorrect == false && sd.ExamQuestion.Question?.Lesson != null)
+			.GroupBy(sd => sd.ExamQuestion.Question.Lesson.Title)
+			.ToDictionary(g => g.Key, g => g.Count());
+
+
+
+		[InverseProperty(nameof(SubmissionDetail.Submission))]
+		public virtual ICollection<SubmissionDetail> SubmissionDetails { get; set; }
 
 		public Submission()
 		{