MongoDB Example (#15029)

* MongoDB Example

* Apply suggestions from code review

* Add changes based on feedback.

* clean up code with more descriptive props

* Use MongoDB in ServerSideProps instead of separate API route

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>

* Update examples/with-mongodb/README.md
Co-authored-by: NLuis Alvarez D. <luis@vercel.com>
Co-authored-by: NLuis Alvarez D <luis@vercel.com>
Co-authored-by: Nkodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

examples/with-mongodb/.env.local.example

+MONGODB_URI=
+MONGODB_DB=
\ No newline at end of file

examples/with-mongodb/.gitignore

+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local

examples/with-mongodb/README.md

+## Example app using MongoDB
+
+[MongoDB](https://www.mongodb.com/) is a general purpose, document-based, distributed database built for modern application developers and for the cloud era. This example will show you how to connect to and use MongoDB as your backend for your Next.js app.
+
+If you want to learn more about MongoDB, visit the following pages:
+
+- [MongoDB Atlas](https://mongodb.com/atlas)
+- [MongoDB Documentation](https://docs.mongodb.com/)
+
+## Deploy your own
+
+Once you have access to the environment variables you'll need, deploy the example using [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example):
+
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/import/git?c=1&s=https://github.com/vercel/next.js/tree/canary/examples/with-mongodb&env=MONGODB_URI,MONGODB_DB&envDescription=Required%20to%20connect%20the%20app%20with%20MongoDB)
+
+## How to use
+
+### Using `create-next-app`
+
+Execute [`create-next-app`](https://github.com/vercel/next.js/tree/canary/packages/create-next-app) with [npm](https://docs.npmjs.com/cli/init) or [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/) to bootstrap the example:
+
+```bash
+npx create-next-app --example with-mongodb with-mongodb
+# or
+yarn create next-app --example with-mongodb with-mongodb
+```
+
+## Configuration
+
+### Set up a MongoDB database
+
+Set up a MongoDB database either locally or with [MongoDB Atlas for free](https://mongodb.com/atlas).
+
+### Set up environment variables
+
+Copy the `env.local.example` file in this directory to `.env.local` (which will be ignored by Git):
+
+```bash
+cp .env.local.example .env.local
+```
+
+Set each variable on `.env.local`:
+
+- `MONGODB_URI` - Your MongoDB connection string. If you are using [MongoDB Atlas](https://mongodb.com/atlas) you can find this by clicking the "Connect" button for your cluster.
+- `MONGODB_DB` - The name of the MongoDB database you want to use.
+
+### Run Next.js in development mode
+
+```bash
+npm install
+npm run dev
+
+# or
+
+yarn install
+yarn dev
+```
+
+Your app should be up and running on [http://localhost:3000](http://localhost:3000)! If it doesn't work, post on [GitHub discussions](https://github.com/zeit/next.js/discussions).
+
+You will either see a message stating "You are connected to MongoDB" or "You are NOT connected to MongoDB". Ensure that you have provided the correct `MONGODB_URI` and `MONGODB_DB` environment variables.
+
+When you are successfully connected, you can refer to the [MongoDB Node.js Driver docs](https://mongodb.github.io/node-mongodb-native/3.4/tutorials/collections/) for further instructions on how to query your database.
+
+## Deploy on Vercel
+
+You can deploy this app to the cloud with [Vercel](https://vercel.com?utm_source=github&utm_medium=readme&utm_campaign=next-example) ([Documentation](https://nextjs.org/docs/deployment)).
+
+#### Deploy Your Local Project
+
+To deploy your local project to Vercel, push it to GitHub/GitLab/Bitbucket and [import to Vercel](https://vercel.com/import/git?utm_source=github&utm_medium=readme&utm_campaign=next-example).
+
+**Important**: When you import your project on Vercel, make sure to click on **Environment Variables** and set them to match your `.env.local` file.
+
+#### Deploy from Our Template
+
+Alternatively, you can deploy using our template by clicking on the Deploy button below.
+
+[![Deploy with Vercel](https://vercel.com/button)](https://vercel.com/import/git?c=1&s=https://github.com/vercel/next.js/tree/canary/examples/with-mongodb&env=MONGODB_URI,MONGODB_DB&envDescription=Required%20to%20connect%20the%20app%20with%20MongoDB)

examples/with-mongodb/package.json

+{
+  "name": "with-mongodb",
+  "version": "0.1.0",
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start"
+  },
+  "dependencies": {
+    "mongodb": "^3.5.9",
+    "next": "latest",
+    "react": "^16.13.1",
+    "react-dom": "^16.13.1"
+  },
+  "license": "MIT"
+}

examples/with-mongodb/pages/index.js

+import Head from 'next/head'
+import { connectToDatabase } from '../util/mongodb'
+
+export default function Home({ isConnected }) {
+  return (
+    <div className="container">
+      <Head>
+        <title>Create Next App</title>
+        <link rel="icon" href="/favicon.ico" />
+      </Head>
+
+      <main>
+        <h1 className="title">
+          Welcome to <a href="https://nextjs.org">Next.js with MongoDB!</a>
+        </h1>
+
+        {isConnected ? (
+          <h2 className="subtitle">You are connected to MongoDB</h2>
+        ) : (
+          <h2 className="subtitle">
+            You are NOT connected to MongoDB. Check the <code>README.md</code>{' '}
+            for instructions.
+          </h2>
+        )}
+
+        <p className="description">
+          Get started by editing <code>pages/index.js</code>
+        </p>
+
+        <div className="grid">
+          <a href="https://nextjs.org/docs" className="card">
+            <h3>Documentation &rarr;</h3>
+            <p>Find in-depth information about Next.js features and API.</p>
+          </a>
+
+          <a href="https://nextjs.org/learn" className="card">
+            <h3>Learn &rarr;</h3>
+            <p>Learn about Next.js in an interactive course with quizzes!</p>
+          </a>
+
+          <a
+            href="https://github.com/vercel/next.js/tree/master/examples"
+            className="card"
+          >
+            <h3>Examples &rarr;</h3>
+            <p>Discover and deploy boilerplate example Next.js projects.</p>
+          </a>
+
+          <a
+            href="https://vercel.com/import?filter=next.js&utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
+            className="card"
+          >
+            <h3>Deploy &rarr;</h3>
+            <p>
+              Instantly deploy your Next.js site to a public URL with Vercel.
+            </p>
+          </a>
+        </div>
+      </main>
+
+      <footer>
+        <a
+          href="https://vercel.com?utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
+          target="_blank"
+          rel="noopener noreferrer"
+        >
+          Powered by{' '}
+          <img src="/vercel.svg" alt="Vercel Logo" className="logo" />
+        </a>
+      </footer>
+
+      <style jsx>{`
+        .container {
+          min-height: 100vh;
+          padding: 0 0.5rem;
+          display: flex;
+          flex-direction: column;
+          justify-content: center;
+          align-items: center;
+        }
+
+        main {
+          padding: 5rem 0;
+          flex: 1;
+          display: flex;
+          flex-direction: column;
+          justify-content: center;
+          align-items: center;
+        }
+
+        footer {
+          width: 100%;
+          height: 100px;
+          border-top: 1px solid #eaeaea;
+          display: flex;
+          justify-content: center;
+          align-items: center;
+        }
+
+        footer img {
+          margin-left: 0.5rem;
+        }
+
+        footer a {
+          display: flex;
+          justify-content: center;
+          align-items: center;
+        }
+
+        a {
+          color: inherit;
+          text-decoration: none;
+        }
+
+        .title a {
+          color: #0070f3;
+          text-decoration: none;
+        }
+
+        .title a:hover,
+        .title a:focus,
+        .title a:active {
+          text-decoration: underline;
+        }
+
+        .title {
+          margin: 0;
+          line-height: 1.15;
+          font-size: 4rem;
+        }
+
+        .title,
+        .description {
+          text-align: center;
+        }
+
+        .subtitle {
+          font-size: 2rem;
+        }
+
+        .description {
+          line-height: 1.5;
+          font-size: 1.5rem;
+        }
+
+        code {
+          background: #fafafa;
+          border-radius: 5px;
+          padding: 0.75rem;
+          font-size: 1.1rem;
+          font-family: Menlo, Monaco, Lucida Console, Liberation Mono,
+            DejaVu Sans Mono, Bitstream Vera Sans Mono, Courier New, monospace;
+        }
+
+        .grid {
+          display: flex;
+          align-items: center;
+          justify-content: center;
+          flex-wrap: wrap;
+
+          max-width: 800px;
+          margin-top: 3rem;
+        }
+
+        .card {
+          margin: 1rem;
+          flex-basis: 45%;
+          padding: 1.5rem;
+          text-align: left;
+          color: inherit;
+          text-decoration: none;
+          border: 1px solid #eaeaea;
+          border-radius: 10px;
+          transition: color 0.15s ease, border-color 0.15s ease;
+        }
+
+        .card:hover,
+        .card:focus,
+        .card:active {
+          color: #0070f3;
+          border-color: #0070f3;
+        }
+
+        .card h3 {
+          margin: 0 0 1rem 0;
+          font-size: 1.5rem;
+        }
+
+        .card p {
+          margin: 0;
+          font-size: 1.25rem;
+          line-height: 1.5;
+        }
+
+        .logo {
+          height: 1em;
+        }
+
+        @media (max-width: 600px) {
+          .grid {
+            width: 100%;
+            flex-direction: column;
+          }
+        }
+      `}</style>
+
+      <style jsx global>{`
+        html,
+        body {
+          padding: 0;
+          margin: 0;
+          font-family: -apple-system, BlinkMacSystemFont, Segoe UI, Roboto,
+            Oxygen, Ubuntu, Cantarell, Fira Sans, Droid Sans, Helvetica Neue,
+            sans-serif;
+        }
+
+        * {
+          box-sizing: border-box;
+        }
+      `}</style>
+    </div>
+  )
+}
+
+export async function getServerSideProps(context) {
+  const { client } = await connectToDatabase()
+
+  const isConnected = await client.isConnected() // Returns true or false
+
+  return {
+    props: { isConnected },
+  }
+}

examples/with-mongodb/public/vercel.svg

+<svg width="283" height="64" viewBox="0 0 283 64" fill="none" 
+    xmlns="http://www.w3.org/2000/svg">
+    <path d="M141.04 16c-11.04 0-19 7.2-19 18s8.96 18 20 18c6.67 0 12.55-2.64 16.19-7.09l-7.65-4.42c-2.02 2.21-5.09 3.5-8.54 3.5-4.79 0-8.86-2.5-10.37-6.5h28.02c.22-1.12.35-2.28.35-3.5 0-10.79-7.96-17.99-19-17.99zm-9.46 14.5c1.25-3.99 4.67-6.5 9.45-6.5 4.79 0 8.21 2.51 9.45 6.5h-18.9zM248.72 16c-11.04 0-19 7.2-19 18s8.96 18 20 18c6.67 0 12.55-2.64 16.19-7.09l-7.65-4.42c-2.02 2.21-5.09 3.5-8.54 3.5-4.79 0-8.86-2.5-10.37-6.5h28.02c.22-1.12.35-2.28.35-3.5 0-10.79-7.96-17.99-19-17.99zm-9.45 14.5c1.25-3.99 4.67-6.5 9.45-6.5 4.79 0 8.21 2.51 9.45 6.5h-18.9zM200.24 34c0 6 3.92 10 10 10 4.12 0 7.21-1.87 8.8-4.92l7.68 4.43c-3.18 5.3-9.14 8.49-16.48 8.49-11.05 0-19-7.2-19-18s7.96-18 19-18c7.34 0 13.29 3.19 16.48 8.49l-7.68 4.43c-1.59-3.05-4.68-4.92-8.8-4.92-6.07 0-10 4-10 10zm82.48-29v46h-9V5h9zM36.95 0L73.9 64H0L36.95 0zm92.38 5l-27.71 48L73.91 5H84.3l17.32 30 17.32-30h10.39zm58.91 12v9.69c-1-.29-2.06-.49-3.2-.49-5.81 0-10 4-10 10V51h-9V17h9v9.2c0-5.08 5.91-9.2 13.2-9.2z" fill="#000"/>
+</svg>
\ No newline at end of file

examples/with-mongodb/util/mongodb.js

+import { MongoClient } from 'mongodb'
+
+let uri = process.env.MONGODB_URI
+let dbName = process.env.MONGODB_DB
+
+let cachedClient = null
+let cachedDb = null
+
+if (!uri) {
+  throw new Error(
+    'Please define the MONGODB_URI environment variable inside .env.local'
+  )
+}
+
+if (!dbName) {
+  throw new Error(
+    'Please define the MONGODB_DB environment variable inside .env.local'
+  )
+}
+
+export async function connectToDatabase() {
+  if (cachedClient && cachedDb) {
+    return { client: cachedClient, db: cachedDb }
+  }
+
+  const client = await MongoClient.connect(uri, {
+    useNewUrlParser: true,
+    useUnifiedTopology: true,
+  })
+
+  const db = await client.db(dbName)
+
+  cachedClient = client
+  cachedDb = db
+
+  return { client, db }
+}