diff --git a/controllers/attachment.js b/controllers/attachment.js
index af52f3c5..1badbc98 100644
--- a/controllers/attachment.js
+++ b/controllers/attachment.js
@@ -3,15 +3,17 @@ const attachmentService = require('~/services/attachment')
 const getMatchOptions = require('~/utils/getMatchOptions')
 const getSortOptions = require('~/utils/getSortOptions')
 const getRegex = require('~/utils/getRegex')
+const getCategoriesOptions = require('~/utils/getCategoriesOption')
 
 const getAttachments = async (req, res) => {
   const { id: author } = req.user
   const { fileName, sort, skip, limit, categories } = req.query
+  const categoriesOptions = getCategoriesOptions(categories)
 
   const match = getMatchOptions({
     author,
     fileName: getRegex(fileName),
-    ...(categories?.length && { category: categories })
+    category: categoriesOptions
   })
   const sortOptions = getSortOptions(sort)
 
diff --git a/controllers/lesson.js b/controllers/lesson.js
index 52c39c2c..bba2c106 100644
--- a/controllers/lesson.js
+++ b/controllers/lesson.js
@@ -1,4 +1,5 @@
 const lessonService = require('~/services/lesson')
+const getCategoriesOptions = require('~/utils/getCategoriesOption')
 const getMatchOptions = require('~/utils/getMatchOptions')
 const getRegex = require('~/utils/getRegex')
 const getSortOptions = require('~/utils/getSortOptions')
@@ -23,8 +24,9 @@ const getLessonById = async (req, res) => {
 const getLessons = async (req, res) => {
   const { id: author } = req.user
   const { title, sort, skip, limit, categories } = req.query
+  const categoriesOptions = getCategoriesOptions(categories)
 
-  const match = getMatchOptions({ author, title: getRegex(title), ...(categories?.length && { category: categories }) })
+  const match = getMatchOptions({ author, title: getRegex(title), category: categoriesOptions })
   const sortOptions = getSortOptions(sort)
 
   const lessons = await lessonService.getLessons(match, sortOptions, parseInt(skip), parseInt(limit))
diff --git a/controllers/question.js b/controllers/question.js
index adde2811..32cafb35 100644
--- a/controllers/question.js
+++ b/controllers/question.js
@@ -1,16 +1,19 @@
 const questionService = require('~/services/question')
+const getCategoriesOptions = require('~/utils/getCategoriesOption')
+const getMatchOptions = require('~/utils/getMatchOptions')
 const getRegex = require('~/utils/getRegex')
 const getSortOptions = require('~/utils/getSortOptions')
 
 const getQuestions = async (req, res) => {
   const { id: author } = req.user
   const { title, sort, skip, limit, categories } = req.query
+  const categoriesOptions = getCategoriesOptions(categories)
 
-  const match = {
+  const match = getMatchOptions({
     author,
     title: getRegex(title),
-    ...(categories?.length && { category: categories })
-  }
+    category: categoriesOptions
+  })
   const sortOptions = getSortOptions(sort)
 
   const questions = await questionService.getQuestions(match, sortOptions, parseInt(skip), parseInt(limit))
diff --git a/controllers/quiz.js b/controllers/quiz.js
index 39777d24..938d6303 100644
--- a/controllers/quiz.js
+++ b/controllers/quiz.js
@@ -1,12 +1,15 @@
 const quizService = require('~/services/quiz')
+const getCategoriesOptions = require('~/utils/getCategoriesOption')
+const getMatchOptions = require('~/utils/getMatchOptions')
 const getRegex = require('~/utils/getRegex')
 const getSortOptions = require('~/utils/getSortOptions')
 
 const getQuizzes = async (req, res) => {
   const { id: author } = req.user
   const { title, sort, skip, limit, categories } = req.query
+  const categoriesOptions = getCategoriesOptions(categories)
 
-  const match = { author, title: getRegex(title), ...(categories?.length && { category: categories }) }
+  const match = getMatchOptions({ author, title: getRegex(title), category: categoriesOptions })
   const sortOptions = getSortOptions(sort)
 
   const quizzes = await quizService.getQuiz(match, sortOptions, parseInt(skip), parseInt(limit))
diff --git a/utils/getCategoriesOption.js b/utils/getCategoriesOption.js
new file mode 100644
index 00000000..23edc82f
--- /dev/null
+++ b/utils/getCategoriesOption.js
@@ -0,0 +1,8 @@
+const getCategoriesOptions = (categories) => {
+  if (categories) {
+    return categories.map((item) => (item === 'null' ? null : item))
+  } else {
+    return
+  }
+}
+module.exports = getCategoriesOptions