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

TechHelper.Server/Context/ApplicationContext.cs

@@ -1,5 +1,4 @@
-using TechHelper.Context.Configuration;
-using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Identity;
 using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore;
 using Entities.Contracts;
@@ -11,31 +10,29 @@ namespace TechHelper.Context
 		public ApplicationContext(DbContextOptions options)
 			: base(options) { }
 
-		public DbSet<AssignmentClass> AssignmentClasses { get; set; }
-		public DbSet<Assignment> Assignments { get; set; }
-		public DbSet<AssignmentQuestion> AssignmentQuestions { get; set; }	
+		public DbSet<School> Schools { get; set; }
+		public DbSet<Grade> Grades { get; set; }
 		public DbSet<Class> Classes { get; set; }	
-		public DbSet<ClassTeacher> ClassStudents { get; set; }	
-		public DbSet<ClassTeacher> ClassTeachers { get; set; }
+		public DbSet<Exam> Exams { get; set; }
+		public DbSet<ExamQuestion> ExamQuestions { get; set; }	
+		public DbSet<ExamAttachment>  ExamAttachments{ get; set; }
+		public DbSet<ExamType> ExamTypes { get; set; }
 		public DbSet<Question> Questions { get; set; }	
 		public DbSet<Submission> Submissions { get; set; }
 		public DbSet<SubmissionDetail> SubmissionDetails { get; set; }	
 		public DbSet<QuestionContext> QuestionContexts { get; set; }	
-		public DbSet<Global> Globals { get; set; }	
 
-		protected override void OnModelCreating(ModelBuilder builder)
-		{
-			base.OnModelCreating(builder);
-			builder.ApplyConfiguration(new RoleConfiguration());
-			builder.ApplyConfiguration(new AssignmentConfiguration());
-			builder.ApplyConfiguration(new AssignmentClassConfiguration());
-			builder.ApplyConfiguration(new AssignmentQuestionConfiguration());
-			builder.ApplyConfiguration(new ClassConfiguration());
-			builder.ApplyConfiguration(new ClassStudentConfiguration());
-			builder.ApplyConfiguration(new ClassTeacherConfiguration());
-			builder.ApplyConfiguration(new QuestionConfiguration());
-			builder.ApplyConfiguration(new SubmissionConfiguration());
-			builder.ApplyConfiguration(new SubmissionDetailConfiguration());
-		}
+		//protected override void OnModelCreating(ModelBuilder builder)
+		//{
+		//	base.OnModelCreating(builder);
+		//	builder.ApplyConfiguration(new RoleConfiguration());
+		//	builder.ApplyConfiguration(new AssignmentConfiguration());
+		//	builder.ApplyConfiguration(new AssignmentClassConfiguration());
+		//	builder.ApplyConfiguration(new AssignmentQuestionConfiguration());
+		//	builder.ApplyConfiguration(new ClassConfiguration());
+		//	builder.ApplyConfiguration(new QuestionConfiguration());
+		//	builder.ApplyConfiguration(new SubmissionConfiguration());
+		//	builder.ApplyConfiguration(new SubmissionDetailConfiguration());
+		//}
 	}
 }

TechHelper.Server/Context/AutoMapperProFile.cs

@@ -1,11 +1,7 @@
 using AutoMapper;
-using AutoMapper.Internal.Mappers;
 using Entities.Contracts;
 using Entities.DTO;
-using Newtonsoft.Json;
-using System.Net.Http.Json;
-using System.Text.Json;
-using System.Text.Json.Serialization;
+using Entities.DTO.Class;
 
 namespace TechHelper.Context
 {
@@ -28,53 +24,91 @@ namespace TechHelper.Context
 		{
 			CreateMap<UserForRegistrationDto, User>()
 				.ForMember(dest => dest.Id, opt => opt.Ignore())
-				.ForMember(dest => dest.UserName, opt => opt.MapFrom(src => src.Name))
+				.ForMember(dest => dest.UserName, opt => opt.MapFrom(src => src.DisplayName))
 				.ForMember(dest => dest.Email, opt => opt.MapFrom(src => src.Email))
 				.ForMember(dest => dest.PhoneNumber, opt => opt.MapFrom(src => src.PhoneNumber))
-				.ForMember(dest => dest.Address, opt => opt.MapFrom(src => src.HomeAddress))
+				.ForMember(dest => dest.HomeAddress, opt => opt.MapFrom(src => src.HomeAddress))
 				.ForMember(dest => dest.PasswordHash, opt => opt.Ignore())
 				.ForMember(dest => dest.EmailConfirmed, opt => opt.Ignore());
 
-			CreateMap<ClassDto, Class>()
-				.ForMember(d => d.Number, o => o.MapFrom(src => src.Class))
-				.ReverseMap();
+			// Subject
+			CreateMap<Subject, SubjectDto>().ReverseMap();
+			CreateMap<Subject, SubjectResponseDto>().ReverseMap();
+			CreateMap<Subject, TypeCommonDto>().ReverseMap();
+
+			// ExamType
+			CreateMap<ExamType, ExamTypeDto>().ReverseMap();
+			CreateMap<ExamType, TypeCommonDto>().ReverseMap();
+
+			// QuestionType
+			CreateMap<QuestionType, QuestionTypeDto	>().ReverseMap();
+			CreateMap<QuestionType, TypeCommonDto>().ReverseMap();
 
 
+			// Exam 
+			CreateMap<ExamDto, Exam>().ReverseMap();
+			CreateMap<Exam, ExamListDto>().ReverseMap();
 
-			// Assignment 
-			CreateMap<AssignmentDto, Assignment>().ReverseMap();
-
-			CreateMap<AssignmentQuestionDto, AssignmentQuestion>().ReverseMap();
+			CreateMap<ExamQuestionDto, ExamQuestion>().ReverseMap();
 
 			CreateMap<QuestionDto, Question>().ReverseMap();
 
-			CreateMap<QuestionContext, QuestionContextDto>().ReverseMap();
-
-
-
-
 			// Submission
 			CreateMap<SubmissionDto, Submission>().ReverseMap();
 
 			CreateMap<SubmissionDetailDto, SubmissionDetail>().ReverseMap();
+			CreateMap<SubmissionTeacherUpdateDto, Submission>().ReverseMap();
 
 			// Student Submission Detail
 			CreateMap<Submission, StudentSubmissionDetailDto>()
-				.ForMember(dest => dest.AssignmentId, opt => opt.MapFrom(src => src.AssignmentId))
+				.ForMember(dest => dest.AssignmentId, opt => opt.MapFrom(src => src.ExamId))
 				.ForMember(dest => dest.StudentId, opt => opt.MapFrom(src => src.StudentId))
 				.ForMember(dest => dest.SubmissionTime, opt => opt.MapFrom(src => src.SubmissionTime))
 				.ForMember(dest => dest.OverallGrade, opt => opt.MapFrom(src => src.OverallGrade))
 				.ForMember(dest => dest.OverallFeedback, opt => opt.MapFrom(src => src.OverallFeedback))
 				.ForMember(dest => dest.Status, opt => opt.MapFrom(src => src.Status));
 
-			CreateMap<Assignment, AssignmentDto>().ReverseMap();
+			CreateMap<Submission, SubmissionListDto>().ReverseMap();
+			CreateMap<SubmissionDetail, SubmissionDetailTeacherUpdateDto>().ReverseMap();
 
 
-			CreateMap<SubjectTypeMetadataDto, Global>()
-					   .ForMember(dest => dest.Info, opt => opt.MapFrom(src => JsonConvert.SerializeObject(src.Data)));
-			CreateMap<Global, SubjectTypeMetadataDto>()
-					   .ForMember(dest => dest.Data, opt => opt.MapFrom(src => JsonConvert.DeserializeObject<Dictionary<string, (string Color, string DisplayName)>>(src.Info)));
+			// School
+			CreateMap<SchoolDto, School>().ReverseMap();
+			CreateMap<SchoolResponseDto, School>().ReverseMap();
 
+			// Grade
+			CreateMap<GradeDto, Grade>().ReverseMap();
+			CreateMap<CreateGradeDto, Grade>().ReverseMap();
+
+
+			// Class
+			CreateMap<ClassDto, Class>().ReverseMap();
+			CreateMap<ClassCreateDto, Class>().ReverseMap();
+
+
+			// User
+			CreateMap<User, UserDto>().ReverseMap();
+			CreateMap<User, UserListDto>().ReverseMap();
+
+			// KeyPoint
+			CreateMap<KeyPoint, KeyPointDto>().ReverseMap();
+			CreateMap<KeyPoint, CreateKeyPointDto>().ReverseMap();
+			CreateMap<KeyPoint, UpdateKeyPointDto>().ReverseMap();
+			CreateMap<KeyPoint, KeyPointResponseDto>().ReverseMap();
+
+			// Lesson
+			CreateMap<Lesson, LessonDto>().ReverseMap();
+			CreateMap<Lesson, CreateLessonDto>().ReverseMap();
+			CreateMap<Lesson, UpdateLessonDto>().ReverseMap();
+			CreateMap<Lesson, LessonResponseDto>().ReverseMap();
+
+			// Textbook
+			CreateMap<Textbook, TextbookDto>().ReverseMap();
+			CreateMap<Textbook, CreateTextbookDto>().ReverseMap();
+			CreateMap<Textbook, UpdateTextbookDto>().ReverseMap();
+			CreateMap<Textbook, TextbookResponseDto>()
+				.ForMember(dest => dest.LessonCount, opt => opt.MapFrom(src => src.Lessons.Count))
+				.ForMember(dest => dest.LessonTitles, opt => opt.MapFrom(src => src.Lessons.Select(l => l.Title).ToList()));
 		}
 	}
 

TechHelper.Server/Context/Configuration/AssignmentAttachmentConfiguration.cs

@@ -4,9 +4,9 @@ using Microsoft.EntityFrameworkCore;
 
 namespace TechHelper.Context.Configuration
 {
-	public class AssignmentAttachmentConfiguration : IEntityTypeConfiguration<AssignmentAttachment>
+	public class AssignmentAttachmentConfiguration : IEntityTypeConfiguration<ExamAttachment>
 	{
-		public void Configure(EntityTypeBuilder<AssignmentAttachment> builder)
+		public void Configure(EntityTypeBuilder<ExamAttachment> builder)
 		{
 			builder.ToTable("assignment_attachments");
 
@@ -38,8 +38,8 @@ namespace TechHelper.Context.Configuration
 				.HasDefaultValue(false);
 
 			// Configure the relationship explicitly
-			builder.HasOne(aa => aa.Assignment) // An AssignmentAttachment has one Assignment
-				   .WithMany(a => a.AssignmentAttachments) // An Assignment has many AssignmentAttachments (assuming 'Attachments' collection in Assignment)
+			builder.HasOne(aa => aa.Exam) // An AssignmentAttachment has one Assignment
+				   .WithMany(a => a.ExamAttachments) // An Assignment has many AssignmentAttachments (assuming 'Attachments' collection in Assignment)
 				   .HasForeignKey(aa => aa.AssignmentId) // The foreign key is AssignmentAttachment.AssignmentId
 				   .IsRequired() // It's a required relationship based on your [Required] attribute
 				   .OnDelete(DeleteBehavior.Cascade); // If an Assignment is deleted, its attachments should also be deleted

TechHelper.Server/Context/Configuration/AssignmentClassConfiguration.cs

@@ -4,18 +4,18 @@ using Microsoft.EntityFrameworkCore;
 
 namespace TechHelper.Context.Configuration
 {
-	public class AssignmentClassConfiguration : IEntityTypeConfiguration<AssignmentClass>
+	public class AssignmentClassConfiguration : IEntityTypeConfiguration<ExamClass>
 	{
-		public void Configure(EntityTypeBuilder<AssignmentClass> builder)
+		public void Configure(EntityTypeBuilder<ExamClass> builder)
 		{
 			// 设置表名为 "assignment_class"
 			builder.ToTable("assignment_class");
 
 			// 设置复合主键
-			builder.HasKey(ac => new { ac.AssignmentId, ac.ClassId });
+			builder.HasKey(ac => new { ac.ExamId, ac.ClassId });
 
 			// 配置 AssignmentId 列名
-			builder.Property(ac => ac.AssignmentId)
+			builder.Property(ac => ac.ExamId)
 				.HasColumnName("assignment_id");
 
 			// 配置 ClassId 列名
@@ -34,15 +34,15 @@ namespace TechHelper.Context.Configuration
 
 			// 配置到 Assignment 的关系 (多对一)
 			// 假设 Assignment 类中有一个名为 AssignmentClasses 的集合属性
-			builder.HasOne(ac => ac.Assignment) // AssignmentClass 有一个 Assignment
+			builder.HasOne(ac => ac.Exam) // AssignmentClass 有一个 Assignment
 				.WithMany(a => a.AssignmentClasses) // Assignment 有多个 AssignmentClass 记录
-				.HasForeignKey(ac => ac.AssignmentId) // 通过 AssignmentId 建立外键
+				.HasForeignKey(ac => ac.ExamId) // 通过 AssignmentId 建立外键
 				.OnDelete(DeleteBehavior.Cascade); // 当 Assignment 被删除时，相关的 AssignmentClass 记录也级联删除
 
 			// 配置到 Class 的关系 (多对一)
 			// 假设 Class 类中有一个名为 AssignmentClasses 的集合属性
 			builder.HasOne(ac => ac.Class) // AssignmentClass 有一个 Class
-				.WithMany(c => c.AssignmentClasses) // Class 有多个 AssignmentClass 记录
+				.WithMany(c => c.ExamClasses) // Class 有多个 AssignmentClass 记录
 				.HasForeignKey(ac => ac.ClassId) // 通过 ClassId 建立外键
 				.OnDelete(DeleteBehavior.Cascade); // 当 Class 被删除时，相关的 AssignmentClass 记录也级联删除
 		}

TechHelper.Server/Context/Configuration/AssignmentConfiguration.cs

@@ -5,9 +5,9 @@ using Microsoft.EntityFrameworkCore.Metadata.Builders;
 
 namespace TechHelper.Context.Configuration
 {
-	public class AssignmentConfiguration : IEntityTypeConfiguration<Assignment>
+	public class AssignmentConfiguration : IEntityTypeConfiguration<Exam>
 	{
-		public void Configure(EntityTypeBuilder<Assignment> builder)
+		public void Configure(EntityTypeBuilder<Exam> builder)
 		{
 			builder.ToTable("assignments");
 
@@ -61,7 +61,7 @@ namespace TechHelper.Context.Configuration
 
 			builder.HasOne(a=>a.ExamStruct)
 				.WithOne()
-				.HasForeignKey<Assignment>(a=>a.ExamStructId)
+				.HasForeignKey<Exam>(a=>a.ExamStructId)
 				.OnDelete(DeleteBehavior.Cascade);
 
 		}

TechHelper.Server/Context/Configuration/AssignmentQuestionConfiguration.cs

@@ -4,9 +4,9 @@ using Microsoft.EntityFrameworkCore;
 
 namespace TechHelper.Context.Configuration
 {
-	public class AssignmentQuestionConfiguration : IEntityTypeConfiguration<AssignmentQuestion>
+	public class AssignmentQuestionConfiguration : IEntityTypeConfiguration<ExamQuestion>
 	{
-		public void Configure(EntityTypeBuilder<AssignmentQuestion> builder)
+		public void Configure(EntityTypeBuilder<ExamQuestion> builder)
 		{
 			// 1. 设置表名
 			builder.ToTable("assignment_questions");
@@ -44,13 +44,13 @@ namespace TechHelper.Context.Configuration
 
 
 			builder.HasOne(aq => aq.Question)             
-				.WithMany(q => q.AssignmentQuestions)     
+				.WithMany(q => q.ExamQuestions)     
 				.HasForeignKey(aq => aq.QuestionId)       
 				.OnDelete(DeleteBehavior.Cascade);        
 
-			builder.HasOne(aq => aq.ParentAssignmentQuestion)
+			builder.HasOne(aq => aq.ParentExamQuestion)
 				.WithMany(aq => aq.ChildrenAssignmentQuestion)
-				.HasForeignKey(aq => aq.ParentAssignmentQuestionId)
+				.HasForeignKey(aq => aq.ParentExamQuestionId)
 				.OnDelete(DeleteBehavior.Cascade);
 
 			builder.HasOne(aq => aq.QuestionContext)

TechHelper.Server/Context/Configuration/ClassConfiguration.cs

@@ -86,7 +86,7 @@ namespace TechHelper.Context.Configuration
 			// 11. 与 AssignmentClass 的关系 (多对多中间表或一对多)
 			// 一对多：一个 Class 有多个 AssignmentClass。一个 AssignmentClass 属于一个 Class。
 			// 假设 AssignmentClass 有 'ClassId' 外键和 'Class' 导航属性。
-			builder.HasMany(c => c.AssignmentClasses) // Class 中的集合导航属性
+			builder.HasMany(c => c.ExamClasses) // Class 中的集合导航属性
 				.WithOne(ac => ac.Class) // 假设 AssignmentClass 中有 'public Class Class { get; set; }'
 				.HasForeignKey(ac => ac.ClassId) // 假设 AssignmentClass 中有 'public Guid ClassId { get; set; }'
 				.OnDelete(DeleteBehavior.Cascade); // 常见：如果一个班级被删除，其作业关联也应被删除。

TechHelper.Server/Context/Configuration/ClassStudentConfiguration.cs

@@ -1,64 +0,0 @@
-using Entities.Contracts;
-using Microsoft.EntityFrameworkCore.Metadata.Builders;
-using Microsoft.EntityFrameworkCore;
-
-namespace TechHelper.Context.Configuration
-{
-	public class ClassStudentConfiguration : IEntityTypeConfiguration<ClassStudent>
-	{
-		public void Configure(EntityTypeBuilder<ClassStudent> builder)
-		{
-			// 1. 设置表名
-			// 将此实体映射到数据库中名为 "class_student" 的表。
-			builder.ToTable("class_student");
-
-			// 2. 设置复合主键
-			// ClassId 和 StudentId 的组合作为主键，确保一个班级中一个学生只有一条入学记录。
-			builder.HasKey(cs => new { cs.ClassId, cs.StudentId });
-
-			// 3. 配置列名和属性特性
-
-			// 配置 ClassId 属性对应的数据库列名为 "class_id"。
-			builder.Property(cs => cs.ClassId)
-				.HasColumnName("class_id");
-
-			// 配置 StudentId 属性对应的数据库列名为 "student_id"。
-			builder.Property(cs => cs.StudentId)
-				.HasColumnName("student_id");
-
-			// 配置 EnrollmentDate 属性对应的数据库列名为 "enrollment_date"，并设置为必需字段。
-			builder.Property(cs => cs.EnrollmentDate)
-				.HasColumnName("enrollment_date")
-				.IsRequired();
-
-			// 配置 IsDeleted 属性对应的数据库列名为 "deleted"，并设置默认值为 false。
-			builder.Property(cs => cs.IsDeleted)
-				.HasColumnName("deleted")
-				.HasDefaultValue(false); // 常用作软删除标记
-
-			// 4. 配置导航属性和外键关系
-
-			// ---
-			// 配置 ClassStudent 到 Class 的关系 (多对一)
-			// 一个 ClassStudent 联结记录属于一个 Class。
-			//
-			// 假设 `Class` 实体中有一个名为 `ClassStudents` 的 `ICollection<ClassStudent>` 集合属性。
-			builder.HasOne(cs => cs.Class)            // 当前 ClassStudent 链接到一个 Class
-				.WithMany(c => c.ClassStudents)       // 那个 Class 可以有多个 ClassStudent 记录
-				.HasForeignKey(cs => cs.ClassId)      // 外键是 ClassStudent.ClassId
-				.OnDelete(DeleteBehavior.Cascade);    // 当 Class 被删除时，相关的 ClassStudent 记录也级联删除。
-
-			// ---
-			// 配置 ClassStudent 到 User (Student) 的关系 (多对一)
-			// 一个 ClassStudent 联结记录属于一个 User (作为 Student)。
-			//
-			// 假设 `User` 实体中有一个名为 `EnrolledClassesLink` 的 `ICollection<ClassStudent>` 集合属性，
-			// 用于表示该用户所注册的班级联结记录 (与 `ClassTeacherConfiguration` 中的模式类似)。
-			builder.HasOne(cs => cs.Student)          // 当前 ClassStudent 链接到一个 User (学生)
-				.WithMany(u => u.EnrolledClassesLink) // 那个 User (学生) 可以有多个 ClassStudent 记录
-				.HasForeignKey(cs => cs.StudentId)    // 外键是 ClassStudent.StudentId
-				.OnDelete(DeleteBehavior.Restrict);   // 当 User (学生) 被删除时，如果还有相关的 ClassStudent 记录，则会阻止删除。
-													  // 这是更安全的做法，以避免意外数据丢失。如果你希望学生被删除时，其所有注册关系也一并删除，可改为 DeleteBehavior.Cascade。
-		}
-	}
-}

TechHelper.Server/Context/Configuration/ClassTeacherConfiguration.cs

@@ -1,61 +0,0 @@
-using Entities.Contracts;
-using Microsoft.EntityFrameworkCore.Metadata.Builders;
-using Microsoft.EntityFrameworkCore;
-
-namespace TechHelper.Context.Configuration
-{
-	public class ClassTeacherConfiguration : IEntityTypeConfiguration<ClassTeacher>
-	{
-		public void Configure(EntityTypeBuilder<ClassTeacher> builder)
-		{
-			// 1. 设置表名
-			// 将此实体映射到数据库中名为 "class_teachers" 的表。
-			builder.ToTable("class_teachers");
-
-			// 2. 设置复合主键
-			// ClassId 和 TeacherId 的组合作为主键，确保一个班级中一个老师只有一条任教记录。
-			// 这要求 ClassTeacher 类中的 ClassId 和 TeacherId 属性上都添加了 [Key] 特性。
-			builder.HasKey(ct => new { ct.ClassId, ct.TeacherId });
-
-			// 3. 配置列名和属性特性
-
-			// 配置 ClassId 属性对应的数据库列名为 "class_id"。
-			builder.Property(ct => ct.ClassId)
-				.HasColumnName("class_id");
-
-			// 配置 TeacherId 属性对应的数据库列名为 "teacher_id"。
-			builder.Property(ct => ct.TeacherId)
-				.HasColumnName("teacher_id");
-
-			// 配置 SubjectTaught 属性对应的数据库列名为 "subject_taught"。
-			// 假设 SubjectTaught 可以为空，所以没有 .IsRequired()
-			builder.Property(ct => ct.SubjectTaught)
-				.HasColumnName("subject_taught");
-
-			// 4. 配置导航属性和外键关系
-
-			// ---
-			// 配置 ClassTeacher 到 Class 的关系 (多对一)
-			// 一个 ClassTeacher 联结记录属于一个 Class。
-			//
-			// 假设 `Class` 实体中有一个名为 `ClassTeachers` 的 `ICollection<ClassTeacher>` 集合属性。
-			builder.HasOne(ct => ct.Class)            // 当前 ClassTeacher 链接到一个 Class
-				.WithMany(c => c.ClassTeachers)       // 那个 Class 可以有多个 ClassTeacher 记录
-				.HasForeignKey(ct => ct.ClassId)      // 外键是 ClassTeacher.ClassId
-				.OnDelete(DeleteBehavior.Cascade);    // 当 Class 被删除时，相关的 ClassTeacher 记录也级联删除。
-
-			// ---
-			// 配置 ClassTeacher 到 User (Teacher) 的关系 (多对一)
-			// 一个 ClassTeacher 联结记录属于一个 User (作为 Teacher)。
-			//
-			// 假设 `User` 实体中有一个名为 `TaughtClassesLink` 的 `ICollection<ClassTeacher>` 集合属性，
-			// 用于表示该用户所教授的班级联结记录。
-			builder.HasOne(ct => ct.Teacher)          // 当前 ClassTeacher 链接到一个 User (老师)
-				.WithMany(u => u.TaughtClassesLink)   // 那个 User (老师) 可以有多个 ClassTeacher 记录 (为所教授的班级)
-				.HasForeignKey(ct => ct.TeacherId)    // 外键是 ClassTeacher.TeacherId
-				.OnDelete(DeleteBehavior.Cascade);   // 当 User (老师) 被删除时，如果还有相关的 ClassTeacher 记录，则会阻止删除。
-													  // 这通常是防止数据丢失的更安全选择。如果你希望老师被删除时，其所有任教关系也一并删除，可改为 DeleteBehavior.Cascade。
-		}
-	}
-	
-}

TechHelper.Server/Context/Configuration/QuestionConfiguration.cs

@@ -95,7 +95,7 @@ namespace TechHelper.Context.Configuration
 			//
 			// 这个关系的外键配置通常在 "多" 的一方（`AssignmentQuestion` 实体）进行。
 			// 假设 `AssignmentQuestion` 实体有一个 `QuestionId` 外键和 `Question` 导航属性。
-			builder.HasMany(q => q.AssignmentQuestions)     // 当前 Question 有多个 AssignmentQuestion
+			builder.HasMany(q => q.ExamQuestions)     // 当前 Question 有多个 AssignmentQuestion
 				.WithOne(aq => aq.Question);                // 每一个 AssignmentQuestion 都有一个 Question
 															// .HasForeignKey(aq => aq.QuestionId); // 外键的配置应在 `AssignmentQuestionConfiguration` 中进行
 

TechHelper.Server/Context/Configuration/SubmissionConfiguration.cs

@@ -21,7 +21,7 @@ namespace TechHelper.Context.Configuration
 				.HasColumnName("id");
 
 			// AssignmentId
-			builder.Property(s => s.AssignmentId)
+			builder.Property(s => s.ExamId)
 				.HasColumnName("assignment_id")
 				.IsRequired();
 
@@ -67,9 +67,9 @@ namespace TechHelper.Context.Configuration
 
 
 
-			builder.HasOne(s => s.Assignment)         // 当前 Submission 有一个 Assignment
+			builder.HasOne(s => s.Exam)         // 当前 Submission 有一个 Assignment
 				.WithMany(a => a.Submissions)         // 那个 Assignment 可以有多个 Submission
-				.HasForeignKey(s => s.AssignmentId)   // 外键是 Submission.AssignmentId
+				.HasForeignKey(s => s.ExamId)   // 外键是 Submission.AssignmentId
 				.OnDelete(DeleteBehavior.Cascade);    // 当 Assignment 被删除时，相关的 Submission 也级联删除。
 
 

TechHelper.Server/Context/Configuration/SubmissionDetailConfiguration.cs

@@ -23,7 +23,7 @@ namespace TechHelper.Context.Configuration
 				.HasColumnName("student_id")
 				.IsRequired();
 
-			builder.Property(sd => sd.AssignmentQuestionId)
+			builder.Property(sd => sd.ExamQuestionId)
 				.HasColumnName("assignment_question_id")
 				.IsRequired();
 
@@ -67,9 +67,9 @@ namespace TechHelper.Context.Configuration
 				.OnDelete(DeleteBehavior.Cascade);           // 当 User (学生) 被删除时，如果他/她还有提交详情，则会阻止删除。
 															  // 这是一个更安全的选择，以防止意外数据丢失。
 
-			builder.HasOne(sd => sd.AssignmentQuestion)          // 当前 SubmissionDetail 有一个 AssignmentQuestion
+			builder.HasOne(sd => sd.ExamQuestion)          // 当前 SubmissionDetail 有一个 AssignmentQuestion
 				.WithMany(aq => aq.SubmissionDetails)           // 那个 AssignmentQuestion 可以有多个 SubmissionDetail 记录
-				.HasForeignKey(sd => sd.AssignmentQuestionId)   // 外键是 SubmissionDetail.AssignmentQuestionId
+				.HasForeignKey(sd => sd.ExamQuestionId)   // 外键是 SubmissionDetail.AssignmentQuestionId
 				.OnDelete(DeleteBehavior.Cascade);              // 当 AssignmentQuestion 被删除时，相关的 SubmissionDetail 记录也级联删除。
 		}
 	}

TechHelper.Server/Context/Configuration/UserConfiguration.cs

@@ -38,7 +38,7 @@ namespace TechHelper.Context.Configuration
 				.OnDelete(DeleteBehavior.Restrict);  // 限制删除：如果创建者有题目，则不允许删除
 
 			// User 作为创建者，与 Assignment 的关系 (一对多)
-			builder.HasMany(u => u.CreatedAssignments) // 一个 User 可以创建多个作业
+			builder.HasMany(u => u.CreatedExams) // 一个 User 可以创建多个作业
 				.WithOne(a => a.Creator)               // 一个 Assignment 对应一个 Creator
 				.HasForeignKey(a => a.CreatorId)       // 外键在 Assignment.CreatedBy
 				.OnDelete(DeleteBehavior.Restrict);    // 限制删除：如果创建者有作业，则不允许删除

TechHelper.Server/Context/DbInitializer.cs

@@ -0,0 +1,22 @@
+using Entities.Contracts;
+using Microsoft.AspNetCore.Identity;
+
+namespace TechHelper.Server.Context
+{
+	public class DbInitializer
+	{
+		public static async Task SeedRoles(RoleManager<IdentityRole<Guid>> roleManager)
+		{
+			string[] defaultRoleName = { "Admin", "Teacher", "Student" };
+
+			foreach (var roleName in defaultRoleName)
+			{
+				if (!await roleManager.RoleExistsAsync(roleName))
+				{
+					await roleManager.CreateAsync(new IdentityRole<Guid>(roleName));
+					Console.WriteLine($"Default role '{roleName}' created successfully.");
+				}
+			}
+		}
+	}
+}