diff --git a/advlabdb/adminModelViews.py b/advlabdb/adminModelViews.py
index bb8de37..5bc4cba 100644
--- a/advlabdb/adminModelViews.py
+++ b/advlabdb/adminModelViews.py
@@ -42,9 +42,9 @@ from .database_import import importFromFile
 from .exceptions import DataBaseException, ModelViewException
 from .model_dependent_funs import (
     initActiveSemesterMenuLinks,
+    lastSemester,
     setUserActiveSemester,
     sortedSemestersStartingWithNewest,
-    userActiveSemester,
 )
 from .models import (
     MAX_MARK,
@@ -70,7 +70,7 @@ from .models import (
 
 
 def semesterExperimentQueryFactory():
-    return SemesterExperiment.query.filter(SemesterExperiment.semester == userActiveSemester())
+    return SemesterExperiment.query.filter(SemesterExperiment.semester == current_user.active_semester)
 
 
 class SemesterRowFilter(FilterEqual):
@@ -150,7 +150,7 @@ class UserView(SecureAdminModelView):
             query_factory=semesterQueryFactory,
             allow_blank=True,
             blank_text="-",
-            default=userActiveSemester,
+            default=lastSemester,
             description="Not fixed and users (including assistants) can change it.",
         )
 
@@ -289,13 +289,13 @@ class RoleView(SecureAdminModelView):
 class SemesterView(SecureAdminModelView):
     class CreateForm(Form):
         def defaultFormLabel():
-            if userActiveSemester().label == "WS":
+            if current_user.active_semester.label == "WS":
                 return "SS"
             else:
                 return "WS"
 
         def defaultFormYear():
-            activeSemester = userActiveSemester()
+            activeSemester = current_user.active_semester
             if activeSemester.label == "WS":
                 return activeSemester.year + 1
             else:
@@ -351,7 +351,7 @@ class SemesterView(SecureAdminModelView):
         return Semester.initFromOldSemester(
             label=form.label.data,
             year=form.year.data,
-            oldSemester=userActiveSemester(),
+            oldSemester=current_user.active_semester,
             transferParts=form.transfer_parts.data,
             transferAssistants=form.transfer_assistants.data,
         )
@@ -370,7 +370,7 @@ class SemesterView(SecureAdminModelView):
         category._children.insert(0, link)
 
     def after_model_change(self, form, model, is_created):
-        setUserActiveSemester(model.id)
+        setUserActiveSemester(model)
 
         SemesterView.addMenuLink(adminSpace, model)
         SemesterView.addMenuLink(assistantSpace, model)
@@ -412,10 +412,10 @@ class PartView(SecureAdminModelView):
     column_searchable_list = ["program.label", "number"]
 
     def queryFilter(self):
-        return Part.semester == userActiveSemester()
+        return Part.semester == current_user.active_semester
 
     def customCreateModel(self, form):
-        return Part(program=form.program.data, number=form.number.data, semester=userActiveSemester())
+        return Part(program=form.program.data, number=form.number.data, semester=current_user.active_semester)
 
 
 class StudentView(SecureAdminModelView):
@@ -469,11 +469,11 @@ class StudentView(SecureAdminModelView):
 
 
 def partQueryFactory():
-    return Part.query.filter(Part.semester == userActiveSemester())
+    return Part.query.filter(Part.semester == current_user.active_semester)
 
 
 def groupQueryFactory():
-    return Group.query.filter(Group.semester == userActiveSemester())
+    return Group.query.filter(Group.semester == current_user.active_semester)
 
 
 class PartRowFilter(FilterEqual):
@@ -481,7 +481,7 @@ class PartRowFilter(FilterEqual):
         if not has_request_context():
             return tuple()
 
-        parts = Part.query.filter(Part.semester == userActiveSemester())
+        parts = Part.query.filter(Part.semester == current_user.active_semester)
         return tuple((part.id, f"{part.program.repr()}{part.number}") for part in parts)
 
 
@@ -568,14 +568,14 @@ class PartStudentView(SecureAdminModelView):
     ]
 
     def queryFilter(self):
-        return PartStudent.part.has(Part.semester == userActiveSemester())
+        return PartStudent.part.has(Part.semester == current_user.active_semester)
 
     def on_model_change(self, form, model, is_created):
         PartStudent.check(model.part, model.group)
 
 
 def partStudentQueryFactory():
-    return PartStudent.query.filter(PartStudent.part.has(Part.semester == userActiveSemester()))
+    return PartStudent.query.filter(PartStudent.part.has(Part.semester == current_user.active_semester))
 
 
 class ProgramRowFilter(FilterEqual):
@@ -635,7 +635,7 @@ class GroupView(SecureAdminModelView):
     refreshFiltersCache = True
 
     def queryFilter(self):
-        return Group.semester == userActiveSemester()
+        return Group.semester == current_user.active_semester
 
     def customCreateModel(self, form):
         return Group.customInit(form.part_students.data)
@@ -796,11 +796,11 @@ class SemesterExperimentView(SecureAdminModelView):
     ]
 
     def queryFilter(self):
-        return SemesterExperiment.semester == userActiveSemester()
+        return SemesterExperiment.semester == current_user.active_semester
 
     def customCreateModel(self, form):
         return SemesterExperiment(
-            semester=userActiveSemester(),
+            semester=current_user.active_semester,
             oral_weighting=form.oral_weighting.data,
             protocol_weighting=form.protocol_weighting.data,
             final_weighting=form.final_weighting.data,
@@ -1052,7 +1052,7 @@ class GroupExperimentView(SecureAdminModelView):
     ]
 
     def queryFilter(self):
-        return GroupExperiment.group.has(Group.semester == userActiveSemester())
+        return GroupExperiment.group.has(Group.semester == current_user.active_semester)
 
     def customCreateModel(self, form):
         return GroupExperiment(semester_experiment=form.semester_experiment.data, group=form.group.data)
@@ -1076,7 +1076,7 @@ class GroupExperimentView(SecureAdminModelView):
 
 def groupExperimentQueryFactory():
     return GroupExperiment.query.filter(
-        GroupExperiment.semester_experiment.has(SemesterExperiment.semester == userActiveSemester())
+        GroupExperiment.semester_experiment.has(SemesterExperiment.semester == current_user.active_semester)
     )
 
 
@@ -1173,7 +1173,7 @@ class AppointmentView(SecureAdminModelView):
 
     def queryFilter(self):
         return Appointment.group_experiment.has(
-            GroupExperiment.semester_experiment.has(SemesterExperiment.semester == userActiveSemester())
+            GroupExperiment.semester_experiment.has(SemesterExperiment.semester == current_user.active_semester)
         )
 
     def customCreateModel(self, form):
@@ -1338,7 +1338,7 @@ class ExperimentMarkView(SecureAdminModelView):
     # Deactivated for the experiments history of a student.
     def queryFilter(self):
         return ExperimentMark.group_experiment.has(
-            GroupExperiment.semester_experiment.has(SemesterExperiment.semester == userActiveSemester())
+            GroupExperiment.semester_experiment.has(SemesterExperiment.semester == current_user.active_semester)
         )
     """
 
@@ -1425,7 +1425,7 @@ class ActionsView(SecureAdminBaseView):
 
         if form.validate_on_submit():
             if form.manualUpdateFinalExperimentAndPartMarksSubmit.data:
-                for semesterExperiment in userActiveSemester().semester_experiments:
+                for semesterExperiment in current_user.active_semester.semester_experiments:
                     semesterExperiment.updateFinalExperimentAndPartMarks()
 
                 flash("Manually updated all final experiment and part marks", "success")
@@ -1519,7 +1519,7 @@ class AnalysisView(SecureAdminBaseView):
                 )
 
             if form.finalPartMarksSubmit.data:
-                parts = userActiveSemester().parts
+                parts = current_user.active_semester.parts
                 activeSemesterFinalPartMarksHists = [
                     AnalysisView.markHist(
                         data=np.array([partStudent.final_part_mark for partStudent in part.part_students]),
diff --git a/advlabdb/assistantModelViews.py b/advlabdb/assistantModelViews.py
index 1b6af43..627ae77 100644
--- a/advlabdb/assistantModelViews.py
+++ b/advlabdb/assistantModelViews.py
@@ -11,7 +11,7 @@ from . import assistantSpace, db
 from .advlabdb_independent_funs import flashRandomPassword, randomPassword
 from .customClasses import SecureAssistantBaseView, SecureAssistantModelView
 from .exceptions import DataBaseException, ModelViewException
-from .model_dependent_funs import initActiveSemesterMenuLinks, userActiveSemester
+from .model_dependent_funs import initActiveSemesterMenuLinks
 from .models import (
     MAX_MARK,
     MIN_MARK,
@@ -53,12 +53,14 @@ class AssistantAppointmentView(SecureAssistantModelView):
     ]
     form_columns = column_editable_list
 
-    def queryFilter(self):
-        return and_(
-            Appointment.group_experiment.has(
-                GroupExperiment.semester_experiment.has(SemesterExperiment.semester == userActiveSemester())
-            ),
-            Appointment.assistant == current_user.assistant,
+    def query_modifier(self, query):
+        return (
+            query.join(GroupExperiment)
+            .join(SemesterExperiment)
+            .where(
+                SemesterExperiment.semester == current_user.active_semester,
+                Appointment.assistant == current_user.assistant,
+            )
         )
 
 
@@ -114,7 +116,7 @@ class AssistantExperimentMarkView(SecureAssistantModelView):
         return ExperimentMark.group_experiment.has(
             GroupExperiment.semester_experiment.has(
                 and_(
-                    SemesterExperiment.semester == userActiveSemester(),
+                    SemesterExperiment.semester == current_user.active_semester,
                     SemesterExperiment.assistants.any(Assistant.user == current_user),
                 )
             )
diff --git a/advlabdb/customClasses.py b/advlabdb/customClasses.py
index e7ae61f..b3a62fa 100644
--- a/advlabdb/customClasses.py
+++ b/advlabdb/customClasses.py
@@ -9,7 +9,6 @@ from sqlalchemy import and_, select
 
 from . import db
 from .exceptions import DataBaseException, ModelViewException
-from .model_dependent_funs import userActiveSemester
 from .model_independent_funs import get_count, reportBadAttempt
 from .models import (
     Assistant,
@@ -45,7 +44,7 @@ class SecureAdminIndexView(CustomIndexView):
             select(ExperimentMark.final_experiment_mark)
             .join(PartStudent)
             .join(Part)
-            .where(Part.semester == userActiveSemester())
+            .where(Part.semester == current_user.active_semester)
         )
         number_of_all_experiment_marks = get_count(active_semester_experiment_mark_ids_stmt)
 
@@ -70,7 +69,7 @@ class SecureAssistantIndexView(CustomIndexView):
             select(ExperimentMark.final_experiment_mark)
             .join(GroupExperiment)
             .join(SemesterExperiment)
-            .where(SemesterExperiment.semester == userActiveSemester())
+            .where(SemesterExperiment.semester == current_user.active_semester)
             .join(SemesterExperiment.assistants)
             .where(Assistant.user == current_user)
         )
diff --git a/advlabdb/model_dependent_funs.py b/advlabdb/model_dependent_funs.py
index 68ab657..ff49cc0 100644
--- a/advlabdb/model_dependent_funs.py
+++ b/advlabdb/model_dependent_funs.py
@@ -24,39 +24,21 @@ def lastSemester():
     return sortedSemestersStartingWithNewest(limit=1).first()
 
 
-def userActiveSemester(flashWarning=False):
-    lastSemesterId = lastSemester().id
-    if current_user.active_semester_id is None:
-        current_user.active_semester_id = lastSemesterId
-        db.session.commit()
-    elif current_user.active_semester_id != lastSemesterId:
-        activeSemester = db.session.get(Semester, current_user.active_semester_id)
-        if activeSemester is not None:
-            if flashWarning:
-                flash(f"You are in the old semester {activeSemester.repr()}!", "warning")
-        else:
-            current_user.active_semester_id = lastSemesterId
+def setUserActiveSemester(semester):
+    if semester is None:
+        flash(f"Can not change the active semester to None!", "error")
+        return
+
+    if current_user.active_semester != semester:
+        try:
+            current_user.active_semester = semester
             db.session.commit()
-            flash("Semester changed!", "warning")
+        except Exception as ex:
+            flash(str(ex), "error")
 
-    return db.session.get(Semester, current_user.active_semester_id)
-
-
-def setUserActiveSemester(semesterId):
-    if current_user.active_semester_id != semesterId:
-        semester = db.session.get(Semester, semesterId)
-        if semester is not None:
-            try:
-                current_user.active_semester_id = semesterId
-                db.session.commit()
-            except Exception as ex:
-                flash(str(ex), "error")
-
-                db.session.rollback()
-            else:
-                flash(f"Active semester changed to {semester.repr()}!", "warning")
+            db.session.rollback()
         else:
-            flash(f"No semester with ID {semesterId}!", "error")
+            flash(f"Active semester changed to {semester.repr()}!", "warning")
 
 
 def initActiveSemesterMenuLinks(space):
diff --git a/advlabdb/routes.py b/advlabdb/routes.py
index aeaaad9..c506978 100644
--- a/advlabdb/routes.py
+++ b/advlabdb/routes.py
@@ -1,13 +1,18 @@
 from flask import flash, redirect, render_template, request, url_for
 from flask_security import auth_required, current_user, roles_accepted, roles_required
 
-from . import app
-from .model_dependent_funs import setUserActiveSemester, userActiveSemester
+from . import app, db
+from .model_dependent_funs import lastSemester, setUserActiveSemester
+from .models import Semester
 
 
 @app.context_processor
 def util_processor():
-    return dict(userActiveSemester=userActiveSemester, current_user=current_user)
+    active_semester = current_user.active_semester
+    if active_semester != lastSemester():
+        flash(f"You are in the old semester {current_user.active_semester.repr()}!", "warning")
+
+    return dict(active_semester=active_semester, current_user=current_user)
 
 
 @app.route("/")
@@ -28,7 +33,8 @@ def set_semester():
     except Exception as ex:
         flash(str(ex), "error")
     else:
-        setUserActiveSemester(semesterId)
+        semester = db.session.get(Semester, semesterId)
+        setUserActiveSemester(semester)
 
     red = request.referrer or url_for("index")
     return redirect(red)
diff --git a/advlabdb/templates/actions.html b/advlabdb/templates/actions.html
index 45a1a02..549cccb 100644
--- a/advlabdb/templates/actions.html
+++ b/advlabdb/templates/actions.html
@@ -2,7 +2,7 @@
 {% extends "admin/master.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
 
     <hr>
 
diff --git a/advlabdb/templates/admin_create.html b/advlabdb/templates/admin_create.html
index 2d9ac8f..0e6dd50 100644
--- a/advlabdb/templates/admin_create.html
+++ b/advlabdb/templates/admin_create.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/create.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/admin_details.html b/advlabdb/templates/admin_details.html
index 3119844..f89e673 100644
--- a/advlabdb/templates/admin_details.html
+++ b/advlabdb/templates/admin_details.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/details.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/admin_edit.html b/advlabdb/templates/admin_edit.html
index 44b0d74..b0314d4 100644
--- a/advlabdb/templates/admin_edit.html
+++ b/advlabdb/templates/admin_edit.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/edit.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/admin_index.html b/advlabdb/templates/admin_index.html
index 3e04a7c..f5accb6 100644
--- a/advlabdb/templates/admin_index.html
+++ b/advlabdb/templates/admin_index.html
@@ -2,11 +2,11 @@
 {% extends "admin/index.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
 
     <hr>
 
     {{missing_final_experiment_marks(number_of_missing_final_experiment_marks, number_of_all_experiment_marks)}}
 
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/admin_list.html b/advlabdb/templates/admin_list.html
index fc60f63..a0f9662 100644
--- a/advlabdb/templates/admin_list.html
+++ b/advlabdb/templates/admin_list.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/list.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/analysis/analysis.html b/advlabdb/templates/analysis/analysis.html
index ff3014a..8ba4ff5 100644
--- a/advlabdb/templates/analysis/analysis.html
+++ b/advlabdb/templates/analysis/analysis.html
@@ -2,7 +2,7 @@
 {% extends "admin/master.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
 
     <hr>
 
diff --git a/advlabdb/templates/analysis/assistant_marks.html b/advlabdb/templates/analysis/assistant_marks.html
index 0d3cbfc..8753375 100644
--- a/advlabdb/templates/analysis/assistant_marks.html
+++ b/advlabdb/templates/analysis/assistant_marks.html
@@ -2,7 +2,7 @@
 {% extends "admin/master.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
 
     <hr>
 
diff --git a/advlabdb/templates/analysis/final_part_marks.html b/advlabdb/templates/analysis/final_part_marks.html
index 9f20ec3..3692077 100644
--- a/advlabdb/templates/analysis/final_part_marks.html
+++ b/advlabdb/templates/analysis/final_part_marks.html
@@ -2,7 +2,7 @@
 {% extends "admin/master.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
 
     <hr>
 
diff --git a/advlabdb/templates/assistant_create.html b/advlabdb/templates/assistant_create.html
index 458f081..d16cf7e 100644
--- a/advlabdb/templates/assistant_create.html
+++ b/advlabdb/templates/assistant_create.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/create.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="assistant")}}
+    {{information(current_user, active_semester, role="assistant")}}
     {{ super() }}
 {% endblock %}
diff --git a/advlabdb/templates/assistant_details.html b/advlabdb/templates/assistant_details.html
index 68a4f72..e2bca28 100644
--- a/advlabdb/templates/assistant_details.html
+++ b/advlabdb/templates/assistant_details.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/details.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="assistant")}}
+    {{information(current_user, active_semester, role="assistant")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/assistant_edit.html b/advlabdb/templates/assistant_edit.html
index ad9da0b..c1435ad 100644
--- a/advlabdb/templates/assistant_edit.html
+++ b/advlabdb/templates/assistant_edit.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/edit.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="assistant")}}
+    {{information(current_user, active_semester, role="assistant")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/assistant_index.html b/advlabdb/templates/assistant_index.html
index c83ee0d..9ef0e7b 100644
--- a/advlabdb/templates/assistant_index.html
+++ b/advlabdb/templates/assistant_index.html
@@ -2,11 +2,11 @@
 {% extends "admin/index.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="assistant")}}
+    {{information(current_user, active_semester, role="assistant")}}
 
     <hr>
 
     {{missing_final_experiment_marks(number_of_missing_final_experiment_marks, number_of_all_experiment_marks)}}
 
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/assistant_list.html b/advlabdb/templates/assistant_list.html
index 8538642..36d767e 100644
--- a/advlabdb/templates/assistant_list.html
+++ b/advlabdb/templates/assistant_list.html
@@ -2,6 +2,6 @@
 {% extends "admin/model/list.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="assistant")}}
+    {{information(current_user, active_semster, role="assistant")}}
     {{ super() }}
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/advlabdb/templates/import.html b/advlabdb/templates/import.html
index 359331f..69a8205 100644
--- a/advlabdb/templates/import.html
+++ b/advlabdb/templates/import.html
@@ -2,7 +2,7 @@
 {% extends "admin/master.html" %}
 
 {% block body %}
-    {{information(current_user, userActiveSemester, role="admin")}}
+    {{information(current_user, active_semester, role="admin")}}
 
     <hr>
 
diff --git a/advlabdb/templates/macros.html b/advlabdb/templates/macros.html
index 9a8c87a..71ca8c4 100644
--- a/advlabdb/templates/macros.html
+++ b/advlabdb/templates/macros.html
@@ -1,7 +1,7 @@
-{% macro information(current_user, userActiveSemester, role) %}
+{% macro information(current_user, active_semester, role) %}
     User: <a href="{{ url_for('index') }}{{ role }}/user/details/?id={{ current_user.id }}">{{ current_user.repr() }}</a>
 
-    | Active semester: {{ userActiveSemester(flashWarning=True).repr() }}
+    | Active semester: {{ active_semester.repr() }}
 
     {% if (role == "admin") and (current_user.has_role("assistant")) %}
         | <a href="{{ url_for('index') }}assistant">Assistant space</a>.
@@ -15,4 +15,4 @@
         Number of <strong>missing</strong> final experiment marks:
         {{ number_of_missing_final_experiment_marks }} / {{ number_of_all_experiment_marks }}
     </p>
-{% endmacro %}
\ No newline at end of file
+{% endmacro %}