重构试卷相关内容

Entities/Contracts/AssignmentQuestion.cs

@@ -16,10 +16,12 @@ namespace Entities.Contracts
 		[Column("id")]
 		public Guid Id { get; set; }
 
-		[Required]
 		[Column("question_id")]
-		[ForeignKey("Question")]
-		public Guid QuestionId { get; set; }
+		public Guid? QuestionId { get; set; } // 设为可空
+
+		// 当 IsGroup 为 true 时，此为 QuestionGroup 的外键
+		[Column("question_group_id")] // 新增一个外键列
+		public Guid? QuestionGroupId { get; set; } // 设为可空
 
 		[Required]
 		[Column("group_id")]
@@ -38,11 +40,16 @@ namespace Entities.Contracts
 		[Column("score")]
 		public float? Score { get; set; }
 
+		[Required]
+		[Column("bgroup")]
+		public bool IsGroup { get; set; }
+
 		[Column("deleted")]
 		public bool IsDeleted { get; set; }
 
 
 		public Question Question { get; set; }
+		public QuestionGroup QuestionGroup { get; set; }	
 		public ICollection<SubmissionDetail> SubmissionDetails { get; set; }
 		public AssignmentGroup AssignmentGroup { get; set; }