# Example App FastAPI / React

This guide walks through the process of setting up authentication using PropelAuth on top of a product built in FastAPI & React.

## [Setting up our Authentication UIs](https://docs.propelauth.com/getting-started/example-apps/react-fastapi#setting-up-our-authentication-uis)

PropelAuth provides UIs for signup, login, and account management, so we don’t need to build them ourselves.

To get started, let’s create a project:

We now actually have all the UIs we need to fully test the experience of our users. The preview button lets you view different pages, like the signup page:

For now, though, let’s customize these UIs, which we can do on the **Look & Feel** section of the dashboard followed by **Open Editor**:

There’s a lot more to discover in the PropelAuth dashboard. We can set up [social logins](https://docs.propelauth.com/overview/authentication/login-methods#social-login-sso), like Login with Google, and enable [passwordless logins via Magic Links](https://docs.propelauth.com/overview/authentication/login-methods#passwordless-magic-links). We can collect more information on signup like [first/last name or accepting terms of service](https://docs.propelauth.com/overview/user-management/user-properties). We can also create and manage [organizations](https://docs.propelauth.com/overview/basics/organizations), if our users need to work together in groups. But, for now, let’s jump right in to building our frontend.

## [Authentication in React](https://docs.propelauth.com/getting-started/example-apps/react-fastapi#authentication-in-react)

### Prereqs

- An application using a [**React-based framework**](https://react.dev/learn/start-a-new-react-project). We use Next.js Pages Router and Typescript for this guide. If you'd prefer to use Vanilla React or Next.js with App Router, check out our [quickstart guide](https://docs.propelauth.com/getting-started/quickstart-fe).

### Next.js Installation

Start by creating a new Next.js project:

```bash
npx create-next-app@latest
```

For this guide we'll be using TypeScript as well as Pages Router, so make sure to set the following when prompted:

```bash
✔ What is your project named? `my-app`
✔ Would you like to use TypeScript? `Yes`
✔ Would you like to use App Router? (recommended) `No`
```

### PropelAuth Installation

We’re going to use PropelAuth's [**@propelauth/react**](https://www.npmjs.com/package/@propelauth/react?ref=propelauth.com) library which allows us to manage our user’s information. Change directory to your Next.js app and run this command:

```bash
npm install @propelauth/react
```

### Run it and update the Dashboard

We are now ready to run the application:

```bash
npm run dev
```

Note down which port the application is running on, and then update the PropelAuth dashboard. We need to configure PropelAuth so that it knows both where the application is running and where to redirect the user back to.

Enter the URL the frontend is running on in the **Primary Frontend Location** section under **Frontend Integration.** For our example, this is `http://localhost:3000`

You’ll also want to copy the Auth URL, as we’ll use it in the next step.

### Set up the AuthProvider

The [AuthProvider](https://docs.propelauth.com/reference/frontend-apis/react#auth-provider) is responsible for checking if the current user is logged in and fetching information about them. You should add it to the top level of your application so it never unmounts. In Next.js, this is the `_app.tsx` file:

```tsx
import type { AppProps } from 'next/app'
import { AuthProvider } from '@propelauth/react'

export default function App({ Component, pageProps }: AppProps) {
    return (
        <AuthProvider authUrl="ENTER_YOUR_AUTH_URL_HERE">
            <Component {...pageProps} />
        </AuthProvider>
    )
}
```

### Displaying user information

And now, the moment you’ve been waiting for! Let’s display the user’s email address via the React hook [useAuthInfo](https://docs.propelauth.com/reference/frontend-apis/react#use-auth-info) . We’ll replace our `index.tsx` file with this:

```tsx
import { useAuthInfo } from '@propelauth/react'

export default function Home() {
    const { loading, isLoggedIn, user } = useAuthInfo()
    if (loading) {
        return <div>Loading...</div>
    } else if (isLoggedIn) {
        return <div>Logged in as {user.email}</div>
    } else {
        return <div>Not logged in</div>
    }
}
```

### Small note: withAuthInfo and withRequiredAuthInfo

`useAuthInfo` is great, but it does mean you have to check the loading state often. PropelAuth also provides a higher-order component [withAuthInfo](https://docs.propelauth.com/reference/frontend-apis/react#with-auth-info) which won’t render the underlying component until loading is finished, making the code a bit cleaner:

```tsx
import { withAuthInfo } from '@propelauth/react'

export default withAuthInfo(function Home({ isLoggedIn, user }) {
    if (isLoggedIn) {
        return <div>Logged in as {user.email}</div>
    } else {
        return <div>Not logged in</div>
    }
})
```

Similarly, if you know the user is logged in, you can use [withRequiredAuthInfo](https://docs.propelauth.com/reference/frontend-apis/react#with-required-auth-info) which can make it even cleaner:

```tsx
import { withRequiredAuthInfo } from '@propelauth/react'

// By default, will redirect the user to the login page if they aren't logged in
export default withRequiredAuthInfo(function Home({ user }) {
    return <div>Logged in as {user.email}</div>
})
```

You can read more about this [here](/content/post/why-we-have-both-react-hooks-and-hocs/index.html).

### Adding Login/Account/Logout Buttons to our application

The `@propelauth/react` library also provides React hooks `useRedirectFunctions` and `useLogoutFunction` which provide easy ways for us to send the user to the hosted pages (like login, signup, account, etc) or log the user out entirely. Let’s update our `index.tsx` file:

```tsx
import { withAuthInfo, useLogoutFunction, useRedirectFunctions } from '@propelauth/react'

export default withAuthInfo(function Home({ isLoggedIn, user }) {
    const { redirectToLoginPage, redirectToAccountPage } = useRedirectFunctions()
    const logoutFn = useLogoutFunction()

if (isLoggedIn) {
        return (
            <>
                <div>Logged in as {user.email}</div>
                <div>
                    <button onClick={() => redirectToAccountPage()}>Account</button>
                    <button onClick={() => logoutFn(false)}>Logout</button>
                </div>
            </>
        )
    } else {
        return (
            <>
                <div>Not logged in</div>
                <button onClick={() => redirectToLoginPage()}>Login</button>
            </>
        )
    }
})
```

## [Sending Requests from Frontend to Backend](https://docs.propelauth.com/getting-started/example-apps/react-fastapi#sending-requests-from-frontend-to-backend)

**Prereqs:**

- To make a request from Next.js to a backend running on a different localhost port, you’ll need to handle [CORS issues](/content/post/avoiding-cors-issues-in-react-next-js/index.html).

For Next.js, we handle CORS locally by adding a rewrite for all `/api/*` routes to our backend on port 3001. This is our `next.config.js`:

```jsx
/** @type {import('next').NextConfig} */
const nextConfig = {
    reactStrictMode: true,
    async rewrites() {
        return [
            {
                source: '/api/:path*',
                destination: 'http://127.0.0.1:3001/api/:path*',
            },
        ]
    },
}

export default nextConfig
```

### Start with an unauthenticated HTTP request

In our Next.js application, let's make a new file `requestdemo.tsx` that uses `useEffect` to make an HTTP request to our backend:

```jsx
import { useEffect, useState } from 'react'
import { withAuthInfo } from '@propelauth/react'

const fetchFromApi = async () => {
    const response = await fetch('/api/whoami', {
        headers: {
            'Content-Type': 'application/json',
        },
    })
    if (response.ok) {
        return response.json()
    } else {
        return { status: response.status }
    }
}

export default withAuthInfo(function RequestDemo() {
    const [response, setResponse] = useState(null)

useEffect(() => {
        fetchFromApi().then((data) => setResponse(data))
    }, [])

if (response) {
        return <pre>{JSON.stringify(response, null, 2)}</pre>
    } else {
        return <div>Loading...</div>
    }
})
```

## [Authentication in FastAPI](https://docs.propelauth.com/getting-started/example-apps/react-fastapi#authentication-in-fast-api)

### Prereqs

- A FastAPI application. If you don’t have one, follow the guide [**here**](https://fastapi.tiangolo.com/#installation).
- A PropelAuth API Key. You can generate one on the **Backend Integration** section of your dashboard.

### Installation

Install the `propelauth-fastapi` library in your project:

```bash
pip install propelauth-fastapi
```

### Creating an unprotected route

Let’s now create the route that our frontend is trying to make a request to:

```python
from fastapi import FastAPI

app = FastAPI()

@app.get("/api/whoami")
def who_am_i():
    return {"Hello": "World"}
```

If we run the application:

```bash
uvicorn main:app --reload --port=3001
```

And then navigate back to the `/requestdemo` page:

## [Protecting our unprotected route]

To lock it down so that only users can access it, all we have to do is initialize the propelauth_fastapi library, and [**dependency inject**](/content/post/a-practical-guide-to-dependency-injection-with-fastapis-depends/index.html) a user.

```python
from fastapi import FastAPI, Depends
from propelauth_fastapi import init_auth, User

app = FastAPI()
auth = init_auth("YOUR_AUTH_URL", "YOUR_API_KEY")

@app.get("/api/whoami")
def read_root(user: User = Depends(auth.require_user)):
    return {"Hello": user.user_id}/
```

And now when we hit the `/requestdemo` endpoint again, we instead get a 401 Unauthorized error!

## [Making an Authenticated HTTP request](https://docs.propelauth.com/getting-started/example-apps/react-fastapi#making-an-authenticated-http-request)

Similar to `user` or `isLoggedIn` , one of the other values that we receive from `useAuthInfo`, `withAuthInfo`, and `withRequiredAuthInfo` is an [accessToken](https://docs.propelauth.com/recipes/access-tokens).

This accessToken is unique to our user, and is what our backend is checking when it says we are authorized or unauthorized. We need to pass this in to our backend via an Authorization header, like so:

```jsx
Authorization: Bearer ${accessToken}
```

Here’s that same component from the last section, but this time it will pass the access token to the backend:

```jsx
import {useEffect, useState} from "react";
import {withAuthInfo} from "@propelauth/react";

const fetchFromApi = async (accessToken: string | null) => {
    const response = await fetch("/api/whoami", {
        headers: {
            "Content-Type": "application/json",
            "Authorization": `Bearer ${accessToken}`
        }
    });
    if (response.ok) {
        return response.json();
    } else {
        return {status: response.status};
    }
}

export default withAuthInfo(function RequestDemo({accessToken}) {
    const [response, setResponse] = useState(null);

useEffect(() => {
        fetchFromApi(accessToken).then((data) => setResponse(data));
    }, [])

if (response) {
        return <pre>{JSON.stringify(response, null, 2)}</pre>
    } else {
        return <div>Loading...</div>
    }
})
```

And now, as long as we are logged in, we see:

## [Organizations, Custom User Schema, Impersonation, and more](https://docs.propelauth.com/getting-started/example-apps/react-fastapi#organizations-custom-user-schema-impersonation-and-more)

Now that you’ve built a basic auth system using PropelAuth, you can easily add more features on top of it. Whether you want to [add organizations](https://docs.propelauth.com/overview/basics/organizations), [collect and store more information about your users](https://docs.propelauth.com/overview/user-management/user-properties), or even [see what your users are seeing](https://docs.propelauth.com/overview/user-management/user-impersonation) - it’s all possible now!