Implemented persistent reorder todo list functionality

backend/.eslintrc.cjs

@@ -1,6 +1,7 @@
 module.exports = {
   env: {
     node: true,
+    "es6": true,
   },
   extends: 'eslint:recommended',
   parserOptions: {

backend/src/app.js

@@ -6,7 +6,8 @@ import {
   createTodoItem,
   fetchTodoItemById,
   updateTodoItem,
-  deleteTodoItem
+  deleteTodoItem,
+  reorderTodoItems
 } from './todo-service.js'
 
 const app = express()
@@ -29,6 +30,12 @@ app.get('/api/todo-list/:listId', async (req, res) => {
   try {
     const todoList = await fetchTodoListById(req.params.listId)
     if (!todoList) return res.status(404).json({ message: 'Todo list not found' })
+
+    // Sort items by order before returning
+    if (todoList.items) {
+      todoList.items.sort((a, b) => (a.order ?? Infinity) - (b.order ?? Infinity))
+    }
+
     res.json(todoList)
   } catch (error) {
     res.status(500).json({ message: error.message })
@@ -63,6 +70,16 @@ app.patch('/api/todo-list/:listId/item/:itemId', async (req, res) => {
   }
 })
 
+app.patch('/api/todo-list/:listId/reorder', async (req, res) => {
+  try {
+    const { itemIds } = req.body
+    const reorderedItems = await reorderTodoItems(req.params.listId, itemIds)
+    res.json(reorderedItems)
+  } catch (error) {
+    res.status(500).json({ message: error.message })
+  }
+})
+
 app.delete('/api/todo-list/:listId/item/:itemId', async (req, res) => {
   try {
     const deletedTodoItem = await deleteTodoItem(req.params.listId, req.params.itemId)

backend/src/data-source.js

@@ -7,10 +7,34 @@ let dataSource = null
 const seedData = async (dataSource) => {
   const todoListRepository = dataSource.getRepository(TodoList)
   const todoItemRepository = dataSource.getRepository(TodoItem)
+
   const firstList = await todoListRepository.save({ title: 'First List' })
-  await todoItemRepository.save({ itemTitle: 'First todo of first list!', list: firstList })
+  await todoItemRepository.save([
+    { 
+      itemTitle: 'First todo of first list!', 
+      list: firstList,
+      order: 0 
+    },
+    { 
+      itemTitle: 'Second todo of first list!', 
+      list: firstList,
+      order: 1 
+    }
+  ])
+
   const secondList = await todoListRepository.save({ title: 'Second List' })
-  await todoItemRepository.save({ itemTitle: 'First todo of second list!', list: secondList })
+  await todoItemRepository.save([
+    { 
+      itemTitle: 'First todo of second list!', 
+      list: secondList,
+      order: 0 
+    },
+    { 
+      itemTitle: 'Second todo of second list!', 
+      list: secondList,
+      order: 1 
+    }
+  ])
 }
 
 export const getAppDataSource = async () => {

backend/src/todo-item.js

@@ -15,6 +15,10 @@ export const TodoItem = new EntitySchema({
       type: Boolean,
       default: false,
     },
+    order: {
+      type: Number,
+      nullable: false,
+    },
   },
   relations: {
     list: {

backend/src/todo-service.js

@@ -17,11 +17,26 @@ export const fetchTodoListById = async (listId) => {
 
 export const createTodoItem = async (listId, todoItemData) => {
   const AppDataSource = await getAppDataSource()
-  const todoList = await AppDataSource.getRepository(TodoList).findOneBy({ id: listId })
+  const todoListRepository = AppDataSource.getRepository(TodoList)
+  const todoItemRepository = AppDataSource.getRepository(TodoItem)
+
+  const todoList = await todoListRepository.findOneBy({ id: listId })
   if (!todoList) throw new Error(`Todo list ${listId} not found`)
-
-  const todoItem = AppDataSource.getRepository(TodoItem).create({ ...todoItemData, list: todoList })
-  return AppDataSource.getRepository(TodoItem).save(todoItem)
+
+  const maxOrderItem = await todoItemRepository.findOne({
+    where: { list: { id: listId } },
+    order: { order: 'DESC' }
+  })
+
+  const newOrder = maxOrderItem ? maxOrderItem.order + 1 : 0
+
+  const todoItem = todoItemRepository.create({ 
+    ...todoItemData, 
+    list: todoList,
+    order: newOrder 
+  })
+
+  return todoItemRepository.save(todoItem)
 }
 
 export const fetchTodoItemById = async (listId, itemId) => {
@@ -56,3 +71,32 @@ export const deleteTodoItem = async (listId, itemId) => {
   await todoRepository.delete(itemId)
   return todoItem
 }
+
+export const reorderTodoItems = async (listId, itemIds) => {
+  const AppDataSource = await getAppDataSource()
+  const todoItemRepository = AppDataSource.getRepository(TodoItem)
+
+  try {
+    const todoItems = await todoItemRepository.find({
+      where: { list: { id: listId } }
+    })
+
+    // Use Promise.all for concurrent updates
+    await Promise.all(itemIds.map((itemId, index) => {
+      const todoItem = todoItems.find(item => item.id === parseInt(itemId))
+
+      if (todoItem) {
+        todoItem.order = index
+        return todoItemRepository.save(todoItem)
+      }
+    }))
+
+    return todoItemRepository.find({
+      where: { list: { id: listId } },
+      order: { order: 'ASC' }
+    })
+  } catch (error) {
+    console.error('Error reordering items:', error)
+    throw error
+  }
+}