aufräumen

2026-08-12 17:45:02 +02:00
parent 0823a023c9
commit a1e722ace1
27 changed files with 542 additions and 197 deletions
@@ -13,6 +13,7 @@ public partial class DashboardViewModel : ObservableObject
    private static readonly CultureInfo De = new("de-DE");

    private readonly IGroupRepository _groups;
+    private readonly ISubjectRepository _subjects;
    private readonly ILessonRepository _lessons;
    private readonly IExamRepository _exams;
    private readonly IWorkTaskRepository _tasks;
@@ -34,10 +35,10 @@ public partial class DashboardViewModel : ObservableObject
    // Navigation-Callback – wird von App.axaml.cs verdrahtet
    public Action<Guid>? OnNavigateToGroup { get; set; }

-    public DashboardViewModel(IGroupRepository groups, ILessonRepository lessons,
+    public DashboardViewModel(IGroupRepository groups, ISubjectRepository subjects, ILessonRepository lessons,
        IExamRepository exams, IWorkTaskRepository tasks, SchoolYearService sy)
    {
-        _groups = groups; _lessons = lessons; _exams = exams; _tasks = tasks; _sy = sy;
+        _groups = groups; _subjects = subjects; _lessons = lessons; _exams = exams; _tasks = tasks; _sy = sy;
        Load();
    }

@@ -70,7 +71,12 @@ public partial class DashboardViewModel : ObservableObject

        CurrentGroups.Clear();
        foreach (var g in groups.Values.OrderBy(g => g.Name))
-            CurrentGroups.Add(new() { GroupId = g.Id, Name = g.Name, Subject = g.Subject ?? "" });
+            CurrentGroups.Add(new()
+            {
+                GroupId = g.Id,
+                Name = g.Name,
+                Subject = g.SubjectId is Guid subjectId ? _subjects.GetById(subjectId)?.Name ?? "" : "",
+            });

        CalendarMonth = FirstOfMonth(now);
        LoadCalendar();
@@ -24,24 +24,24 @@ public partial class ExamGradingDialogViewModel : ObservableObject
    public ObservableCollection<ExamResultRow> Rows { get; } = [];

    public ExamGradingDialogViewModel(IExamResultRepository results, IStudentRepository students,
-        IEnrollmentRepository enrollments, GradingService grading, Exam exam, Guid groupId, string schoolYear)
+        IGroupMembershipRepository memberships, GradingService grading, Exam exam, Guid groupId)
    {
        _results = results; _grading = grading; _exam = exam;
        Tasks = exam.Tasks.OrderBy(t => t.Nr).ToList();
        _examMaxPoints = Tasks.Sum(t => t.MaxPoints);

-        var enrolled = students.GetByGroup(groupId, schoolYear);
-        var enrollmentList = enrollments.GetByGroupAndYear(groupId, schoolYear);
+        var enrolled = students.GetByGroup(groupId);
+        var membershipList = memberships.GetByGroup(groupId);
        var existing = results.GetByExam(exam.Id).ToDictionary(r => r.StudentId);

        foreach (var s in enrolled.OrderBy(s => s.LastName).ThenBy(s => s.FirstName))
        {
-            var enrollment = enrollmentList.FirstOrDefault(e => e.StudentId == s.Id);
-            if (enrollment is not null && !IsEnrolledAtDate(enrollment, exam.Date)) continue;
+            var membership = membershipList.FirstOrDefault(e => e.StudentId == s.Id);
+            if (membership is not null && !IsMemberAtDate(membership, exam.Date)) continue;

            // Niveau-Klausur: nur Schüler mit passendem Niveau zeigen. Klausuren ohne
            // Niveau-Zuordnung gelten weiterhin für die ganze Gruppe.
-            if (exam.Niveau.HasValue && enrollment?.Niveau != exam.Niveau) continue;
+            if (exam.Niveau.HasValue && membership?.Niveau != exam.Niveau) continue;

            existing.TryGetValue(s.Id, out var result);
            var row = new ExamResultRow(s.Id, s.FullName, Tasks, result, _exam.GradingKey, _examMaxPoints, _grading);
@@ -52,12 +52,12 @@ public partial class ExamGradingDialogViewModel : ObservableObject

    private void SaveRow(ExamResultRow row) => _results.Save(row.ToModel(_exam.Id));

-    private static bool IsEnrolledAtDate(Enrollment e, DateOnly date) => e.Period switch
+    private static bool IsMemberAtDate(GroupMembership membership, DateOnly date) => membership.Period switch
    {
-        EnrollmentPeriod.H1Only => date.Month >= 8 || date.Month <= 1,
-        EnrollmentPeriod.H2Only => date.Month >= 2 && date.Month <= 7,
-        EnrollmentPeriod.Custom => (e.JoinedAt is null || date >= e.JoinedAt.Value)
-                                 && (e.LeftAt  is null || date <= e.LeftAt.Value),
+        MembershipPeriod.H1Only => date.Month >= 8 || date.Month <= 1,
+        MembershipPeriod.H2Only => date.Month >= 2 && date.Month <= 7,
+        MembershipPeriod.Custom => (membership.JoinedAt is null || date >= membership.JoinedAt.Value)
+                                && (membership.LeftAt  is null || date <= membership.LeftAt.Value),
        _                       => true,
    };
 }
@@ -289,7 +289,6 @@ public partial class ExamDialogViewModel : ObservableObject
        Result = _editingExam ?? new Exam { GroupId = _groupId };
        Result.Title      = Title.Trim();
        Result.Date       = date;
-        Result.Subject    = _subjectName.Trim();
        Result.ExamNumber = ExamNumber;
        Result.Notes      = string.IsNullOrWhiteSpace(Notes) ? null : Notes.Trim();
        Result.ReturnedAt = returnedAt;
@@ -12,7 +12,7 @@ namespace LehrerApp.Desktop.ViewModels.Groups;
 public partial class GroupListViewModel : ObservableObject
 {
    private readonly IGroupRepository _groups;
-    private readonly SchoolYearService _sy;
+    private readonly ISubjectRepository _subjects;

    public Action<Guid, int>? OnNavigateToDetail { get; set; }
    public Func<Task>? OnAddGroup { get; set; }
@@ -37,9 +37,9 @@ public partial class GroupListViewModel : ObservableObject
    public ObservableCollection<string> SchoolYears { get; } = [];
    public ObservableCollection<GroupListItem> Groups { get; } = [];

-    public GroupListViewModel(IGroupRepository groups, SchoolYearService sy)
+    public GroupListViewModel(IGroupRepository groups, ISubjectRepository subjects, SchoolYearService sy)
    {
-        _groups = groups; _sy = sy;
+        _groups = groups; _subjects = subjects;
        foreach (var y in sy.RecentSchoolYears()) SchoolYears.Add(y);
        SelectedSchoolYear = sy.CurrentSchoolYear();
    }
@@ -63,11 +63,13 @@ public partial class GroupListViewModel : ObservableObject
        Groups.Clear();
        var all = _groups.GetBySchoolYear(SelectedSchoolYear, includeInactive: ShowArchived)
            .Where(g => g.IsActive != ShowArchived);
+        var subjectNames = _subjects.GetAll().ToDictionary(s => s.Id, s => s.Name);
        var filtered = string.IsNullOrWhiteSpace(SearchText) ? all
            : all.Where(g => g.Name.Contains(SearchText, StringComparison.OrdinalIgnoreCase)
-                          || (g.Subject?.Contains(SearchText, StringComparison.OrdinalIgnoreCase) ?? false));
+                          || (g.SubjectId is Guid id && subjectNames.GetValueOrDefault(id, "")
+                              .Contains(SearchText, StringComparison.OrdinalIgnoreCase)));
        foreach (var g in filtered.OrderBy(g => g.Name))
-            Groups.Add(new GroupListItem(g));
+            Groups.Add(new GroupListItem(g, g.SubjectId is Guid id ? subjectNames.GetValueOrDefault(id, "") : ""));
        SelectedGroup = Groups.FirstOrDefault(g => g.Id == selectedId);
        OnPropertyChanged(nameof(ListSummary));
        OnPropertyChanged(nameof(HasNoGroups));
@@ -136,15 +138,15 @@ public class GroupListItem
    public bool IsActive { get; }
    public string ArchiveActionLabel => IsActive ? "Archivieren" : "Wieder aktivieren";

-    public GroupListItem(LearningGroup g)
+    public GroupListItem(LearningGroup g, string subjectName)
    {
        Id           = g.Id;
        IsActive     = g.IsActive;
        Name         = g.Name;
-        Subject      = g.Subject ?? "";
+        Subject      = subjectName;
        TypeLabel    = g.Type == GroupType.Class ? "Klasse" : "Kurs";
        GradingLabel = g.GradingSystem == GradingSystem.Grades1To6 ? "1–6" : "0–15";
-        DisplayName  = string.IsNullOrEmpty(g.Subject) ? g.Name : $"{g.Name} · {g.Subject}";
+        DisplayName  = string.IsNullOrEmpty(subjectName) ? g.Name : $"{g.Name} · {subjectName}";
        Subtitle     = $"{TypeLabel} · Stufe {g.GradeLevel} · Noten {GradingLabel} · {g.SchoolYear}";
    }
 }
@@ -155,7 +157,8 @@ public partial class GroupDetailViewModel : ObservableObject
 {
    private readonly IGroupRepository _groups;
    private readonly IStudentRepository _students;
-    private readonly IEnrollmentRepository _enrollments;
+    private readonly IGroupMembershipRepository _memberships;
+    private readonly ISubjectRepository _subjects;
    private readonly IExamRepository _exams;
    private readonly IGradeRepository _grades;

@@ -171,6 +174,7 @@ public partial class GroupDetailViewModel : ObservableObject
    // bevor LoadGroup() läuft (siehe MainWindowViewModel.NavigateToGroupDetail), Group ist dann
    // kurzzeitig null — ein verschachtelter Pfad würde dafür jedes Mal einen Binding-Fehler loggen.
    public bool IsDifferentiated => Group?.IsDifferentiated ?? false;
+    public string SubjectName { get; private set; } = "";

    partial void OnGroupChanged(LearningGroup? value) => OnPropertyChanged(nameof(IsDifferentiated));

@@ -187,10 +191,11 @@ public partial class GroupDetailViewModel : ObservableObject
    public Func<Exam, Task>? OnEvaluateExam { get; set; }

    public GroupDetailViewModel(IGroupRepository groups, IStudentRepository students,
-        IEnrollmentRepository enrollments, IExamRepository exams, IGradeRepository grades,
+        IGroupMembershipRepository memberships, ISubjectRepository subjects,
+        IExamRepository exams, IGradeRepository grades,
        ParticipationTabViewModel participationTab)
    {
-        _groups = groups; _students = students; _enrollments = enrollments;
+        _groups = groups; _students = students; _memberships = memberships; _subjects = subjects;
        _exams = exams; _grades = grades;
        ParticipationTab = participationTab;
    }
@@ -199,6 +204,9 @@ public partial class GroupDetailViewModel : ObservableObject
    {
        Group = _groups.GetById(id);
        if (Group is null) return;
+        SubjectName = Group.SubjectId is Guid subjectId
+            ? _subjects.GetById(subjectId)?.Name ?? ""
+            : "";
        GroupTitle    = Group.Name;
        GroupSubtitle = $"{Group.SchoolYear} · " +
                        $"{(Group.Type == GroupType.Class ? "Klasse" : "Kurs")} · " +
@@ -221,14 +229,13 @@ public partial class GroupDetailViewModel : ObservableObject
    {
        if (Group is null) return;
        Students.Clear();
-        var enrolled    = _students.GetByGroup(Group.Id, Group.SchoolYear);
-        var enrollments = _enrollments.GetByGroupAndYear(Group.Id, Group.SchoolYear)
-                          .ToDictionary(e => e.StudentId);
+        var enrolled = _students.GetByGroup(Group.Id);
+        var memberships = _memberships.GetByGroup(Group.Id).ToDictionary(e => e.StudentId);
        StudentCount = enrolled.Count;
        foreach (var s in enrolled)
        {
-            enrollments.TryGetValue(s.Id, out var enr);
-            var summary = new StudentSummary(s, enr) { OnChanged = SaveStudentNiveau };
+            memberships.TryGetValue(s.Id, out var membership);
+            var summary = new StudentSummary(s, membership) { OnChanged = SaveStudentNiveau };
            Students.Add(summary);
        }
    }
@@ -236,11 +243,10 @@ public partial class GroupDetailViewModel : ObservableObject
    private void SaveStudentNiveau(StudentSummary summary)
    {
        if (Group is null) return;
-        var enrollment = _enrollments.GetByGroupAndYear(Group.Id, Group.SchoolYear)
-            .FirstOrDefault(e => e.StudentId == summary.Id);
-        if (enrollment is null) return;
-        enrollment.Niveau = summary.Niveau;
-        _enrollments.Save(enrollment);
+        var membership = _memberships.GetByStudentAndGroup(summary.Id, Group.Id);
+        if (membership is null) return;
+        membership.Niveau = summary.Niveau;
+        _memberships.Save(membership);
    }

    [RelayCommand]
@@ -259,10 +265,9 @@ public partial class GroupDetailViewModel : ObservableObject
    private void RemoveStudent()
    {
        if (Group is null || SelectedStudent is null) return;
-        var enrollment = _enrollments.GetByGroupAndYear(Group.Id, Group.SchoolYear)
-            .FirstOrDefault(e => e.StudentId == SelectedStudent.Id);
-        if (enrollment is null) return;
-        _enrollments.Delete(enrollment.Id);
+        var membership = _memberships.GetByStudentAndGroup(SelectedStudent.Id, Group.Id);
+        if (membership is null) return;
+        _memberships.Delete(membership.Id);
        LoadStudents();
        SelectedStudent = null;
        ParticipationTab.RefreshCurrentGrid();
@@ -422,18 +427,18 @@ public partial class StudentSummary : ObservableObject

    public Action<StudentSummary>? OnChanged { get; set; }

-    public StudentSummary(Core.Models.Student s, Enrollment? e)
+    public StudentSummary(Core.Models.Student s, GroupMembership? membership)
    {
        Id     = s.Id;
        FullName = s.FullName;
-        PeriodLabel = e?.Period switch
+        PeriodLabel = membership?.Period switch
        {
-            EnrollmentPeriod.H1Only => "H1",
-            EnrollmentPeriod.H2Only => "H2",
-            EnrollmentPeriod.Custom => BuildCustomLabel(e),
+            MembershipPeriod.H1Only => "H1",
+            MembershipPeriod.H2Only => "H2",
+            MembershipPeriod.Custom => BuildCustomLabel(membership),
            _                       => "",
        };
-        _niveau = e?.Niveau;
+        _niveau = membership?.Niveau;
    }

    partial void OnNiveauChanged(Niveau? value)
@@ -442,11 +447,11 @@ public partial class StudentSummary : ObservableObject
        OnChanged?.Invoke(this);
    }

-    private static string BuildCustomLabel(Enrollment e)
+    private static string BuildCustomLabel(GroupMembership membership)
    {
-        if (e.JoinedAt.HasValue && e.LeftAt.HasValue) return $"{e.JoinedAt:dd.MM.}–{e.LeftAt:dd.MM.}";
-        if (e.JoinedAt.HasValue) return $"ab {e.JoinedAt:dd.MM.}";
-        if (e.LeftAt.HasValue)   return $"bis {e.LeftAt:dd.MM.}";
+        if (membership.JoinedAt.HasValue && membership.LeftAt.HasValue) return $"{membership.JoinedAt:dd.MM.}–{membership.LeftAt:dd.MM.}";
+        if (membership.JoinedAt.HasValue) return $"ab {membership.JoinedAt:dd.MM.}";
+        if (membership.LeftAt.HasValue)   return $"bis {membership.LeftAt:dd.MM.}";
        return "Datum";
    }
 }
@@ -491,35 +496,34 @@ public class ExamSummary
 public partial class AddStudentToGroupDialogViewModel : ObservableObject
 {
    private readonly IStudentRepository    _students;
-    private readonly IEnrollmentRepository _enrollments;
+    private readonly IGroupMembershipRepository _memberships;
    private readonly Guid   _groupId;
-    private readonly string _schoolYear;

    [ObservableProperty] private string            _searchText        = "";
    [ObservableProperty] private StudentPickerItem? _selectedStudent;
    [ObservableProperty] private string            _validationMessage  = "";
-    [ObservableProperty] private EnrollmentPeriod  _period             = EnrollmentPeriod.FullYear;
+    [ObservableProperty] private MembershipPeriod  _period             = MembershipPeriod.FullYear;
    [ObservableProperty] private string            _joinedAtText       = "";
    [ObservableProperty] private string            _leftAtText         = "";

-    public bool IsFullYear { get => Period == EnrollmentPeriod.FullYear; set { if (value) Period = EnrollmentPeriod.FullYear; } }
-    public bool IsH1Only   { get => Period == EnrollmentPeriod.H1Only;   set { if (value) Period = EnrollmentPeriod.H1Only; } }
-    public bool IsH2Only   { get => Period == EnrollmentPeriod.H2Only;   set { if (value) Period = EnrollmentPeriod.H2Only; } }
-    public bool IsCustom   { get => Period == EnrollmentPeriod.Custom;   set { if (value) Period = EnrollmentPeriod.Custom; } }
-    public bool IsCustomPeriod => Period == EnrollmentPeriod.Custom;
+    public bool IsFullYear { get => Period == MembershipPeriod.FullYear; set { if (value) Period = MembershipPeriod.FullYear; } }
+    public bool IsH1Only   { get => Period == MembershipPeriod.H1Only;   set { if (value) Period = MembershipPeriod.H1Only; } }
+    public bool IsH2Only   { get => Period == MembershipPeriod.H2Only;   set { if (value) Period = MembershipPeriod.H2Only; } }
+    public bool IsCustom   { get => Period == MembershipPeriod.Custom;   set { if (value) Period = MembershipPeriod.Custom; } }
+    public bool IsCustomPeriod => Period == MembershipPeriod.Custom;

    public ObservableCollection<StudentPickerItem> AvailableStudents { get; } = [];
-    public Enrollment? Result { get; private set; }
+    public GroupMembership? Result { get; private set; }

    public AddStudentToGroupDialogViewModel(IStudentRepository students,
-        IEnrollmentRepository enrollments, Guid groupId, string schoolYear)
+        IGroupMembershipRepository memberships, Guid groupId)
    {
-        _students = students; _enrollments = enrollments;
-        _groupId = groupId; _schoolYear = schoolYear;
+        _students = students; _memberships = memberships;
+        _groupId = groupId;
        LoadAvailableStudents();
    }

-    partial void OnPeriodChanged(EnrollmentPeriod value)
+    partial void OnPeriodChanged(MembershipPeriod value)
    {
        OnPropertyChanged(nameof(IsFullYear));
        OnPropertyChanged(nameof(IsH1Only));
@@ -532,11 +536,11 @@ public partial class AddStudentToGroupDialogViewModel : ObservableObject

    private void LoadAvailableStudents()
    {
-        var alreadyEnrolled = _enrollments.GetByGroupAndYear(_groupId, _schoolYear)
+        var alreadyAssigned = _memberships.GetByGroup(_groupId)
            .Select(e => e.StudentId).ToHashSet();
        var all = _students.GetAll();
        var available = all
-            .Where(s => !alreadyEnrolled.Contains(s.Id))
+            .Where(s => !alreadyAssigned.Contains(s.Id))
            .Where(s => string.IsNullOrWhiteSpace(SearchText) ||
                        s.FullName.Contains(SearchText, StringComparison.OrdinalIgnoreCase));
        AvailableStudents.Clear();
@@ -549,7 +553,7 @@ public partial class AddStudentToGroupDialogViewModel : ObservableObject
        if (SelectedStudent is null) { ValidationMessage = "Bitte einen Schüler auswählen."; return; }

        DateOnly? joinedAt = null, leftAt = null;
-        if (Period == EnrollmentPeriod.Custom)
+        if (Period == MembershipPeriod.Custom)
        {
            if (!string.IsNullOrWhiteSpace(JoinedAtText) &&
                DateOnly.TryParseExact(JoinedAtText, "dd.MM.yyyy",
@@ -561,16 +565,15 @@ public partial class AddStudentToGroupDialogViewModel : ObservableObject
                leftAt = l;
        }

-        Result = new Enrollment
+        Result = new GroupMembership
        {
            StudentId  = SelectedStudent.Id,
            GroupId    = _groupId,
-            SchoolYear = _schoolYear,
            Period     = Period,
            JoinedAt   = joinedAt,
            LeftAt     = leftAt,
        };
-        _enrollments.Save(Result);
+        _memberships.Save(Result);
    }
 }

@@ -587,11 +590,8 @@ public partial class AddGroupDialogViewModel : ObservableObject
 {
    private readonly IGroupRepository   _groups;
    private readonly ISubjectRepository _subjects;
-    private readonly SchoolYearService  _sy;
-    private readonly IEnrollmentRepository _enrollments;
    private List<Subject> _allSubjects = [];
    private LearningGroup? _editingGroup;
-    private string? _originalSchoolYear;

    public List<string> TypeOptions { get; } = ["Klasse", "Kurs"];
    [ObservableProperty] private string _selectedTypeName = "Kurs";
@@ -625,9 +625,9 @@ public partial class AddGroupDialogViewModel : ObservableObject
    public string SaveButtonText => _editingGroup is null ? "Anlegen" : "Speichern";

    public AddGroupDialogViewModel(IGroupRepository groups, ISubjectRepository subjects,
-        SchoolYearService sy, IEnrollmentRepository enrollments)
+        SchoolYearService sy)
    {
-        _groups = groups; _subjects = subjects; _sy = sy; _enrollments = enrollments;
+        _groups = groups; _subjects = subjects;
        _allSubjects      = subjects.GetAll();
        KnownSubjectNames = _allSubjects.Select(s => s.Name).ToList();
        SchoolYears       = sy.RecentSchoolYears(3);
@@ -642,10 +642,9 @@ public partial class AddGroupDialogViewModel : ObservableObject
    public void LoadForEdit(LearningGroup group)
    {
        _editingGroup = group;
-        _originalSchoolYear = group.SchoolYear;
        SelectedTypeName = group.Type == GroupType.Class ? "Klasse" : "Kurs";
        Name = group.Name;
-        Subject = group.Subject ?? "";
+        Subject = group.SubjectId is Guid subjectId ? _subjects.GetById(subjectId)?.Name ?? "" : "";
        GradeLevel = group.GradeLevel;
        SelectedGradingName = group.GradingSystem == GradingSystem.Grades1To6
            ? "Noten 1–6" : "Punkte 0–15";
@@ -684,7 +683,6 @@ public partial class AddGroupDialogViewModel : ObservableObject

        Result = _editingGroup ?? new LearningGroup();
        Result.Name          = Name.Trim();
-        Result.Subject       = subjectName;
        Result.SubjectId     = subjectId;
        Result.Type          = IsKurs ? GroupType.Course : GroupType.Class;
        Result.GradeLevel    = GradeLevel;
@@ -695,14 +693,5 @@ public partial class AddGroupDialogViewModel : ObservableObject
        Result.IsOwnClass    = IsOwnClass;
        Result.IsDifferentiated = IsDifferentiated;
        _groups.Save(Result);
-
-        if (_editingGroup is not null && _originalSchoolYear != SelectedSchoolYear)
-        {
-            foreach (var enrollment in _enrollments.GetByGroup(Result.Id))
-            {
-                enrollment.SchoolYear = SelectedSchoolYear;
-                _enrollments.Save(enrollment);
-            }
-        }
    }
 }
@@ -16,7 +16,7 @@ public partial class ParticipationGradeDialogViewModel : ObservableObject
    private readonly IParticipationRepository _entries;
    private readonly IParticipationAspectRepository _aspects;
    private readonly IStudentRepository _students;
-    private readonly IEnrollmentRepository _enrollments;
+    private readonly IGroupMembershipRepository _memberships;
    private readonly IGradeRepository _grades;
    private readonly GradingService _grading;
    private readonly Guid _groupId;
@@ -39,11 +39,11 @@ public partial class ParticipationGradeDialogViewModel : ObservableObject
    public ParticipationGradeDialogViewModel(
        IParticipationSessionRepository sessions, IParticipationRepository entries,
        IParticipationAspectRepository aspects, IStudentRepository students,
-        IEnrollmentRepository enrollments, IGradeRepository grades, GradingService grading,
+        IGroupMembershipRepository memberships, IGradeRepository grades, GradingService grading,
        Guid groupId, string schoolYear, GradingSystem gradingSystem)
    {
        _sessions = sessions; _entries = entries; _aspects = aspects;
-        _students = students; _enrollments = enrollments; _grades = grades;
+        _students = students; _memberships = memberships; _grades = grades;
        _grading = grading; _groupId = groupId; _schoolYear = schoolYear;
        _gradingSystem = gradingSystem;

@@ -83,14 +83,14 @@ public partial class ParticipationGradeDialogViewModel : ObservableObject
            .OrderBy(s => s.Date)
            .ToList();

-        var studentList = _students.GetByGroup(_groupId, _schoolYear);
-        var enrollmentList = _enrollments.GetByGroupAndYear(_groupId, _schoolYear);
+        var studentList = _students.GetByGroup(_groupId);
+        var membershipList = _memberships.GetByGroup(_groupId);

        foreach (var student in studentList.OrderBy(s => s.LastName).ThenBy(s => s.FirstName))
        {
-            var enrollment = enrollmentList.FirstOrDefault(e => e.StudentId == student.Id);
+            var membership = membershipList.FirstOrDefault(e => e.StudentId == student.Id);
            var relevantSessions = sessions
-                .Where(s => enrollment is null || IsEnrolledAtDate(enrollment, s.Date))
+                .Where(s => membership is null || IsMemberAtDate(membership, s.Date))
                .ToList();

            var points = new List<(DateOnly Date, double Rating)>();
@@ -132,7 +132,6 @@ public partial class ParticipationGradeDialogViewModel : ObservableObject
                {
                    StudentId = row.StudentId,
                    GroupId = _groupId,
-                    SchoolYear = _schoolYear,
                    Category = GradeCategory.Participation,
                    Note = noteTag,
                };
@@ -153,12 +152,12 @@ public partial class ParticipationGradeDialogViewModel : ObservableObject
        _                      => true,
    };

-    private static bool IsEnrolledAtDate(Enrollment e, DateOnly date) => e.Period switch
+    private static bool IsMemberAtDate(GroupMembership membership, DateOnly date) => membership.Period switch
    {
-        EnrollmentPeriod.H1Only => date.Month >= 8 || date.Month <= 1,
-        EnrollmentPeriod.H2Only => date.Month >= 2 && date.Month <= 7,
-        EnrollmentPeriod.Custom => (e.JoinedAt is null || date >= e.JoinedAt.Value)
-                                 && (e.LeftAt  is null || date <= e.LeftAt.Value),
+        MembershipPeriod.H1Only => date.Month >= 8 || date.Month <= 1,
+        MembershipPeriod.H2Only => date.Month >= 2 && date.Month <= 7,
+        MembershipPeriod.Custom => (membership.JoinedAt is null || date >= membership.JoinedAt.Value)
+                                && (membership.LeftAt  is null || date <= membership.LeftAt.Value),
        _                       => true,
    };
 }
@@ -15,7 +15,7 @@ public partial class ParticipationTabViewModel : ObservableObject
    private readonly IParticipationRepository        _entries;
    private readonly IParticipationAspectRepository  _aspects;
    private readonly IStudentRepository              _students;
-    private readonly IEnrollmentRepository           _enrollments;
+    private readonly IGroupMembershipRepository      _memberships;
    private readonly IGroupRepository                _groups;
    private readonly ICompetencyDomainRepository     _competencyDomains;

@@ -53,13 +53,13 @@ public partial class ParticipationTabViewModel : ObservableObject
        IParticipationRepository entries,
        IParticipationAspectRepository aspects,
        IStudentRepository students,
-        IEnrollmentRepository enrollments,
+        IGroupMembershipRepository memberships,
        IGroupRepository groups,
        ICompetencyDomainRepository competencyDomains)
    {
        _sessions         = sessions;    _entries     = entries;
        _aspects          = aspects;     _students    = students;
-        _enrollments      = enrollments; _groups      = groups;
+        _memberships      = memberships; _groups      = groups;
        _competencyDomains = competencyDomains;
    }

@@ -128,18 +128,18 @@ public partial class ParticipationTabViewModel : ObservableObject
        StudentRows.Clear();
        var session     = _sessions.GetById(sessionId);
        var sessionDate = session?.Date ?? DateOnly.FromDateTime(DateTime.Today);
-        var students    = _students.GetByGroup(_groupId, _schoolYear);
-        var enrollments = _enrollments.GetByGroupAndYear(_groupId, _schoolYear);
+        var students    = _students.GetByGroup(_groupId);
+        var memberships = _memberships.GetByGroup(_groupId);
        var entries     = _entries.GetBySession(sessionId);

        foreach (var s in students)
        {
-            var enrollment = enrollments.FirstOrDefault(e => e.StudentId == s.Id);
-            if (enrollment is not null && !IsEnrolledAtDate(enrollment, sessionDate))
+            var membership = memberships.FirstOrDefault(e => e.StudentId == s.Id);
+            if (membership is not null && !IsMemberAtDate(membership, sessionDate))
                continue;

            var entry = entries.FirstOrDefault(e => e.StudentId == s.Id)
-                        ?? new ParticipationEntry { SessionId = sessionId, GroupId = _groupId, StudentId = s.Id };
+                        ?? new ParticipationEntry { SessionId = sessionId, StudentId = s.Id };
            var row = new ParticipationStudentRow(s.Id, s.FullName, entry, Aspects.ToList(), ActiveCompetencyCodes);
            row.OnRatingChanged           = (sid, key, val)  => SaveRating(sessionId, sid, key, val);
            row.OnCompetencyRatingChanged = (sid, code, val) => SaveCompetencyRating(sessionId, sid, code, val);
@@ -149,25 +149,22 @@ public partial class ParticipationTabViewModel : ObservableObject
        RebuildColumnsSignal++;
    }

-    private static bool IsEnrolledAtDate(Enrollment e, DateOnly date) => e.Period switch
+    private static bool IsMemberAtDate(GroupMembership membership, DateOnly date) => membership.Period switch
    {
-        EnrollmentPeriod.H1Only => date.Month >= 8 || date.Month <= 1,
-        EnrollmentPeriod.H2Only => date.Month >= 2 && date.Month <= 7,
-        EnrollmentPeriod.Custom => (e.JoinedAt is null || date >= e.JoinedAt.Value)
-                                 && (e.LeftAt  is null || date <= e.LeftAt.Value),
+        MembershipPeriod.H1Only => date.Month >= 8 || date.Month <= 1,
+        MembershipPeriod.H2Only => date.Month >= 2 && date.Month <= 7,
+        MembershipPeriod.Custom => (membership.JoinedAt is null || date >= membership.JoinedAt.Value)
+                                && (membership.LeftAt  is null || date <= membership.LeftAt.Value),
        _                       => true,
    };

    private void SaveRating(Guid sessionId, Guid studentId, string key, int? value)
    {
-        var session = _sessions.GetById(sessionId);
-        var entry   = _entries.GetBySessionAndStudent(sessionId, studentId)
+        var entry = _entries.GetBySessionAndStudent(sessionId, studentId)
                      ?? new ParticipationEntry
                      {
                          SessionId = sessionId,
-                          GroupId   = _groupId,
                          StudentId = studentId,
-                          Date      = session?.Date ?? DateOnly.FromDateTime(DateTime.Today),
                      };

        var existing = entry.Ratings.FirstOrDefault(r => r.Key == key);
@@ -280,14 +277,11 @@ public partial class ParticipationTabViewModel : ObservableObject

    private void SaveCompetencyRating(Guid sessionId, Guid studentId, string code, int? value)
    {
-        var session = _sessions.GetById(sessionId);
-        var entry   = _entries.GetBySessionAndStudent(sessionId, studentId)
+        var entry = _entries.GetBySessionAndStudent(sessionId, studentId)
                      ?? new ParticipationEntry
                      {
                          SessionId = sessionId,
-                          GroupId   = _groupId,
                          StudentId = studentId,
-                          Date      = session?.Date ?? DateOnly.FromDateTime(DateTime.Today),
                      };
        var existing = entry.CompetencyRatings.FirstOrDefault(r => r.Code == code);
        if (value is null)
@@ -110,7 +110,15 @@ public partial class SettingsViewModel : ObservableObject
    private void AddSubject()
    {
        if (string.IsNullOrWhiteSpace(NewName)) { ValidationMessage = "Name erforderlich."; return; }
-        _subjects.Save(new Subject { Name = NewName.Trim(), ShortName = NewShort.Trim() });
+        try
+        {
+            _subjects.Save(new Subject { Name = NewName.Trim(), ShortName = NewShort.Trim() });
+        }
+        catch (InvalidOperationException ex)
+        {
+            ValidationMessage = ex.Message;
+            return;
+        }
        NewName = ""; NewShort = ""; ValidationMessage = "";
        LoadSubjects();
    }
@@ -119,7 +127,16 @@ public partial class SettingsViewModel : ObservableObject
    private void DeleteSubject(SubjectListItem? item)
    {
        if (item is null) return;
-        _subjects.Delete(item.Id);
+        try
+        {
+            _subjects.Delete(item.Id);
+        }
+        catch (InvalidOperationException ex)
+        {
+            ValidationMessage = ex.Message;
+            return;
+        }
+        ValidationMessage = "";
        if (CatalogSubject?.Id == item.Id) CatalogSubject = null;
        LoadSubjects();
    }
@@ -68,8 +68,9 @@ public class StudentListItem
 public partial class StudentDetailViewModel : ObservableObject
 {
    private readonly IStudentRepository _students;
-    private readonly IEnrollmentRepository _enrollments;
+    private readonly IGroupMembershipRepository _memberships;
    private readonly IGroupRepository _groups;
+    private readonly ISubjectRepository _subjects;
    private readonly IDocumentationRepository _docs;

    [ObservableProperty] private Student? _student;
@@ -79,7 +80,7 @@ public partial class StudentDetailViewModel : ObservableObject
    [ObservableProperty] private string _editLastName = "";
    [ObservableProperty] private ContactItem? _selectedContact;

-    public ObservableCollection<EnrollmentEntry> Enrollments   { get; } = [];
+    public ObservableCollection<GroupMembershipEntry> GroupMemberships { get; } = [];
    public ObservableCollection<DocEntry>        Documentation { get; } = [];
    public ObservableCollection<ContactItem>     Contacts      { get; } = [];
    public bool HasNoContacts => Contacts.Count == 0;
@@ -87,11 +88,11 @@ public partial class StudentDetailViewModel : ObservableObject
    public Action<ContactItem>? OnViewAddress { get; set; }

    public StudentDetailViewModel(IStudentRepository students,
-        IEnrollmentRepository enrollments, IGroupRepository groups,
+        IGroupMembershipRepository memberships, IGroupRepository groups, ISubjectRepository subjects,
        IDocumentationRepository docs)
    {
-        _students = students; _enrollments = enrollments;
-        _groups = groups; _docs = docs;
+        _students = students; _memberships = memberships;
+        _groups = groups; _subjects = subjects; _docs = docs;
    }

    public void LoadStudent(Guid id)
@@ -102,12 +103,13 @@ public partial class StudentDetailViewModel : ObservableObject
        EditFirstName = Student.FirstName;
        EditLastName  = Student.LastName;

-        Enrollments.Clear();
-        foreach (var e in _enrollments.GetByStudent(Student.Id))
+        GroupMemberships.Clear();
+        foreach (var membership in _memberships.GetByStudent(Student.Id))
        {
-            var g = _groups.GetById(e.GroupId);
+            var g = _groups.GetById(membership.GroupId);
            if (g is null) continue;
-            Enrollments.Add(new() { SchoolYear = e.SchoolYear, GroupName = g.Name, Subject = g.Subject ?? "" });
+            var subject = g.SubjectId is Guid subjectId ? _subjects.GetById(subjectId)?.Name ?? "" : "";
+            GroupMemberships.Add(new() { SchoolYear = g.SchoolYear, GroupName = g.Name, Subject = subject });
        }

        LoadContacts();
@@ -195,7 +197,7 @@ public partial class StudentDetailViewModel : ObservableObject
    private bool CanViewSelectedAddress() => SelectedContact?.HasAddress == true;
 }

-public class EnrollmentEntry { public string SchoolYear { get; set; } = ""; public string GroupName { get; set; } = ""; public string Subject { get; set; } = ""; }
+public class GroupMembershipEntry { public string SchoolYear { get; set; } = ""; public string GroupName { get; set; } = ""; public string Subject { get; set; } = ""; }
 public class DocEntry { public string Date { get; set; } = ""; public string Title { get; set; } = ""; public string TypeLabel { get; set; } = ""; public bool IsConfidential { get; set; } }

 public class ContactItem