Video 93: Promise Chaining

playground/8-promises.js

@@ -1,12 +1,28 @@
-const doWorkPromise = new Promise((resolve, reject) => {
+const add = (a, b) => {
+  return new Promise((resolve, reject) => {
     setTimeout(() => {
-    reject('Things went wrong!')
-    // resolve([7, 4, 1])
+      resolve(a + b)
     }, 2000)
   })
+}
 
-doWorkPromise.then((result) => {
-  console.log('Success!', result)
-}).catch((error) => {
-  console.log('Error!', error)
+// add(1, 2).then((sum) => {
+//   console.log(sum)
+//
+//   add(sum, 5).then((sum2) => {
+//     console.log(sum2)
+//   }).catch((e) => {
+//     console.log(e)
+//   })
+// }).catch((e) => {
+//   console.log(e)
+// })
+
+add(1, 1).then((sum) => {
+  console.log(sum)
+  return add(sum, 4)
+}).then((sum2) => {
+  console.log(sum2)
+}).catch((e) => {
+  console.log(e)
 })

task-manager/playground/promise-chaining.js

@@ -0,0 +1,13 @@
+require('../src/db/mongoose')
+const User = require('../src/models/user')
+
+// 5e519e3404357c00d0777aee
+
+User.findByIdAndUpdate('5e52f2612f736700e5a20797', { age: 1 }).then((user) => {
+  console.log(user)
+  return User.countDocuments({ age: 1 })
+}).then((result) => {
+  console.log(result)
+}).catch((e) => {
+  console.log(e)
+})

task-manager/src/db/mongoose.js

@@ -2,5 +2,6 @@ const mongoose = require('mongoose')
 
 mongoose.connect('mongodb://localhost:27017/task-manager-api', {
   useNewUrlParser: true,
-  useCreateIndex: true
+  useCreateIndex: true,
+  useFindAndModify: false
 })