重构试卷相关内容

Entities/Contracts/QuestionGroup.cs

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+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("question_groups")]
+	public class QuestionGroup
+	{
+		[Key]
+		[Column("id")]
+		public Guid Id { get; set; }
+
+		[Column("title")]
+		[MaxLength(255)]
+		public string Title { get; set; }
+
+		[Required]
+		[Column("description")]
+		[MaxLength(65535)]
+		public string Description { get; set; }
+
+		[Column("type")]
+		[MaxLength(50)]
+		public string Type { get; set; }
+
+		[Column("difficulty_level")]
+		[MaxLength(10)]
+		public DifficultyLevel DifficultyLevel { get; set; }
+
+		[Column("subject_area")]
+		public SubjectAreaEnum SubjectArea { get; set; }
+
+		[Column("total_questions")]
+		public int TotalQuestions { get; set; } = 0;
+
+		[Column("parent_question_group")]
+		public Guid? ParentQG { get; set; }
+
+		[Required]
+		[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; }
+
+		[Column("valid_group")]
+		public bool ValidGroup { get; set; }
+
+
+
+		public User Creator { get; set; }
+		public QuestionGroup ParentQuestionGroup { get; set; }
+		public ICollection<QuestionGroup> ChildQuestionGroups { get; set; }
+		public ICollection<AssignmentQuestion> AssignmentQuestions { get; set; }
+		public ICollection<Question> Questions { get; set; }
+
+		public QuestionGroup()
+		{
+			Id = Guid.NewGuid();
+			Questions = new HashSet<Question>();
+			CreatedAt = DateTime.UtcNow;
+			UpdatedAt = DateTime.UtcNow;
+			IsDeleted = false;
+			ValidGroup = true;
+		}
+	}
+}