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

Entities/Contracts/Question.cs

@@ -24,35 +24,38 @@ namespace Entities.Contracts
 		[MaxLength(65535)]
 		public string? Answer { get; set; }
 
-
-
 		[Required]
 		[Column("type")]
-		[MaxLength(20)]
-		public QuestionType Type { get; set; } = QuestionType.Unknown;
-
-		[Column("difficulty_level")]
-		[MaxLength(10)] 
-		public DifficultyLevel DifficultyLevel { get; set; } = DifficultyLevel.easy;
+		public Guid QuestioTypeId { get; set; }
+		[ForeignKey(nameof(QuestioTypeId))]
+		public virtual QuestionType QuestionType { get; set; }
 
 		[Column("subject_area")]
-		public SubjectAreaEnum SubjectArea { get; set; } = SubjectAreaEnum.Unknown;
-
-		public string QType { get; set; } = string.Empty;
-
-		[Column("options")]
-		public string? Options { get; set; }
+		public Guid SubjectId { get; set; }
+		[ForeignKey(nameof(SubjectId))]
+		public virtual Subject Subject { get; set; }
 
 		[Column("key_point")]
 		public Guid? KeyPointId { get; set; }
+		[ForeignKey(nameof(KeyPointId))]
+		public virtual KeyPoint? KeyPoint { get; set; }
 
 		[Column("lesson")]
 		public Guid? LessonId { get; set; }
+		[ForeignKey(nameof(LessonId))]
+		public virtual Lesson? Lesson { get; set; }
 
-		
-		[Required]
-		[Column("created_by")]
-		public Guid CreatorId { get; set; }
+		//[Required]
+		//[Column("created_by")]
+		//public Guid CreatorId { get; set; }
+		//[ForeignKey(nameof(CreatorId))]
+		//public virtual User Creator { get; set; }
+
+		//[Column("difficulty_level")]
+		//public DifficultyLevel DifficultyLevel { get; set; } = DifficultyLevel.easy;
+
+		[Column("options")]
+		public string? Options { get; set; }
 
 		[Column("created_at")]
 		public DateTime CreatedAt { get; set; }
@@ -63,22 +66,13 @@ namespace Entities.Contracts
 		[Column("deleted")]
 		public bool IsDeleted { get; set; }
 
-
-		// Navigation Properties
-		[ForeignKey(nameof(CreatorId))]
-		public User Creator { get; set; }
-
-		[ForeignKey(nameof(KeyPointId))]
-		public KeyPoint? KeyPoint { get; set; }
-		[ForeignKey(nameof(LessonId))]	
-		public Lesson? Lesson { get; set; }
-		
-		public ICollection<AssignmentQuestion>? AssignmentQuestions { get; set; }
+		[InverseProperty(nameof(ExamQuestion.Question))]
+		public virtual ICollection<ExamQuestion>? ExamQuestions { get; set; }
 
 		public Question()
 		{
 			Id = Guid.NewGuid();
-			AssignmentQuestions = new HashSet<AssignmentQuestion>();
+			ExamQuestions = new HashSet<ExamQuestion>();
 		}
 	}