#306

backend/app/controllers/materials_controller.rb

@@ -14,10 +14,15 @@ class MaterialsController < ApplicationController
 
     tag_id = params[:tag_id].presence
     parent_id = params[:parent_id].presence
+    unclassified = bool?(:unclassified)
 
     q = Material.includes(:tag, :created_by_user, :material_export_items).with_attached_file
-    q = q.where(tag_id:) if tag_id
-    q = q.where(parent_id:) if parent_id
+    if unclassified
+      q = q.where(tag_id: nil)
+    else
+      q = q.where(tag_id:) if tag_id
+      q = q.where(parent_id:) if parent_id
+    end
 
     count = q.count
     materials = q.order(created_at: :desc, id: :desc).limit(limit).offset(offset)