Limit single file field block for PAF

hypha/apply/projects/admin.py

 from wagtail.contrib.modeladmin.options import ModelAdmin, ModelAdminGroup
 
+from .admin_views import CreateProjectApprovalFormView, EditProjectApprovalFormView
 from .models import DocumentCategory, ProjectApprovalForm
 
 
@@ -13,6 +14,8 @@ class ProjectApprovalFormAdmin(ModelAdmin):
     model = ProjectApprovalForm
     menu_icon = 'form'
     list_display = ('name', 'used_by',)
+    create_view_class = CreateProjectApprovalFormView
+    edit_view_class = EditProjectApprovalFormView
 
     def used_by(self, obj):
         rows = list()

hypha/apply/projects/admin_views.py

+from wagtail.contrib.modeladmin.views import CreateView, EditView
+
+from hypha.apply.utils.blocks import show_admin_form_error_messages
+
+
+class CreateProjectApprovalFormView(CreateView):
+
+    def get_form(self):
+        """
+        Overriding this method to disable the single file block option from Project Approval Form.
+        Set 0 as max_number of single file can be added to make single file block option unavailable or disable.
+        """
+        form = super(CreateProjectApprovalFormView, self).get_form()
+        form.fields['form_fields'].block.meta.block_counts = {'file': {'min_num': 0, 'max_num': 0}}
+        return form
+
+    def form_invalid(self, form):
+        show_admin_form_error_messages(self.request, form)
+        return self.render_to_response(self.get_context_data(form=form))
+
+
+class EditProjectApprovalFormView(EditView):
+
+    def get_form(self):
+        """
+        Overriding this method to disable the single file block option from Project Approval Form.
+        Calculating the number of Single file blocks that exist in the instance already.
+        And set that count as max_number of single file block can be added to make single file option disable.
+        """
+        form = super(EditProjectApprovalFormView, self).get_form()
+        single_file_count = sum(1 for block in self.get_instance().form_fields.raw_data if block['type'] == 'file')
+        form.fields['form_fields'].block.meta.block_counts = {'file': {'min_num': 0, 'max_num': single_file_count}}
+        return form
+
+    def form_invalid(self, form):
+        show_admin_form_error_messages(self.request, form)
+        return self.render_to_response(self.get_context_data(form=form))