Further polishing for subject

stude/courses/admin.py

@@ -1,5 +1,6 @@
 from django.contrib import admin
-from .models import Course
+from .models import Course, SubjectCourse
 
 
 admin.site.register(Course)
+admin.site.register(SubjectCourse)

stude/subjects/admin.py

@@ -1,5 +1,10 @@
 from django.contrib import admin
+from courses.models import Course
 from .models import Subject
 
 
-admin.site.register(Subject)
+class SubjectAdmin(admin.ModelAdmin):
+    filter_horizontal = ['courses']
+
+
+admin.site.register(Subject, SubjectAdmin)

stude/subjects/serializers.py

@@ -1,16 +1,20 @@
 from rest_framework import serializers
 from .models import Subject
+from courses.models import Course
 from year_levels.serializers import YearLevelSerializer
 from semesters.serializers import SemesterSerializer
+from courses.serializers import CourseSerializer
 
 
 class SubjectSerializer(serializers.ModelSerializer):
     year_level = serializers.SerializerMethodField()
     semester = serializers.SerializerMethodField()
+    courses = serializers.SlugRelatedField(
+        queryset=Course.objects.all(), many=True, slug_field='name', allow_null=True)
 
     class Meta:
         model = Subject
-        fields = '__all__'
+        fields = ('name', 'code', 'courses', 'year_level', 'semester')
 
     def get_year_level(self, obj):
         return obj.year_level.name