add ChoiceField for template name

fet2020/core/forms.py

@@ -1,9 +1,17 @@
 from ckeditor_uploader.widgets import CKEditorUploadingWidget
 from django import forms
+from django.utils.translation import gettext_lazy as _
+
 from .models import CustomFlatPage
 
 
 class FlatPageForm(forms.ModelForm):
+    __choices = [
+        ("flatpages/default.html", _("default.html")),
+        ("flatpages/social_media.html", _("social_media.html")),
+    ]
+    template_name = forms.ChoiceField(choices=__choices)
+    
     class Meta:
         model = CustomFlatPage
         fields = '__all__'