error TS2339: Property 'build' does not exist on type 'Model<TodoDoc>

package.json

@@ -58,7 +58,7 @@
     "karma-jasmine": "~3.3.0",
     "karma-jasmine-html-reporter": "^1.5.0",
     "protractor": "~7.0.0",
-    "ts-node": "~8.3.0",
+    "ts-node": "^8.3.0",
     "ts-node-dev": "^1.0.0",
     "tslint": "~6.1.0",
     "typescript": "^3.9.7"

src/index.ts

 import express from 'express';
-import mongoose from 'mongoose';
+import mongoose from 'mongoose'
 import { json } from 'body-parser';
 import { todoRouter } from './routes/todo'
 
@@ -7,14 +7,14 @@ const app = express()
 app.use(json())
 app.use(todoRouter)
 
-mongoose.connect('mongodb://localhost:27017/todo', {
-    useCreateIndex: true,
-    useNewUrlParser: true,
-    useUnifiedTopology: true
+mongoose.connect('mongodb://localhost:27017/test-todo', {
+  useNewUrlParser: true,
+  useCreateIndex: true,
+  useUnifiedTopology: true
 }, () => {
-    console.log('connected to database')
+  console.log('connected to database')
 })
 
 app.listen(3000, () => {
-    console.log('server is listening on port 3000')
+  console.log('server is listening on port 3000')
 })
\ No newline at end of file

src/models/todo.ts

+import mongoose from 'mongoose'
+
+interface ITodo {
+  title: string;
+  description: string;
+}
+
+interface todoModelInterface extends mongoose.Model<TodoDoc> {
+  build(attr: ITodo): TodoDoc
+}
+
+interface TodoDoc extends mongoose.Document {
+  title: string;
+  description: string;
+}
+
+const todoSchema = new mongoose.Schema({
+  title: {
+    type: String,
+    required: true
+  },
+  description: {
+    type: String, 
+    required: true
+  }
+})
+
+todoSchema.statics.build = (attr: ITodo) => {
+  return new Todo(attr)
+}
+
+const Todo = mongoose.model<TodoDoc, todoModelInterface>('Todo', todoSchema)
+
+Todo.build({
+  title: 'some title',
+  description: 'some description'
+})
+
+export { Todo }
\ No newline at end of file

src/routes/todo.ts

-import express, { Request, Response} from 'express'
+import express, { Request, Response } from 'express'
+import { Todo } from '../models/todo'
 
 const router = express.Router()
 
-router.get('/api/todo', [], (req: Request, res: Response) => {
-    return res.send('the todo')
+router.get('/api/todo', async (req: Request, res: Response) => {
+  const todo = await Todo.find({})
+  return res.status(200).send(todo)
 })
 
-router.post('/api/todo', (req, res) => {
-    return res.send('new todo created')
+router.post('/api/todo', async (req: Request, res: Response) => {
+  const { title, description } = req.body;
+
+  const todo = Todo.build({ title, description })
+  await todo.save()
+  return res.status(201).send(todo)
 })
 
 export { router as todoRouter }
\ No newline at end of file