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Setting up authentication in Astro with Prisma and Planetscale

Phone with passcode screen
| 4 min read
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I’ve been wanting to add authentication to my personal website for a while now to see how it works in Astro. With Prisma and PlanetScale already running for comments on my blogs, I decided to store my account information in PlanetScale. Because it’s just used for my own account, and I’m not storing any other sensitive information in my database, I decided to store the credentials in plain text for now. I changed my Prisma schema to make this possible:

src/schema.prisma
model Account {
  id Int @id @default(autoincrement())
  username String @unique
  password String
}

Once the model is updated in the code, running npx prisma db push propagates the changes to PlanetScale, so the schema is updated in the actual database.

I used an existing package called @astro-auth to handle all the authentication on my site. For this to work, I needed to add 2 environment variables to my application: ASTROAUTH_URL (the URL my site is hosted on) and ASTROAUTH_SECRET (a self chosen secret key).

Because I stored the credentials in PlanetScale, I needed to use the CredentialProvider to enable logging in with username and password. There are many other providers available on @astro-auth, go check out the package if you’re interested. The code needed to set this up with @astro-auth looks like this:

src/pages/api/auth/[...astroauth].ts
import AstroAuth from "@astro-auth/core";
import { CredentialProvider } from "@astro-auth/providers";
import { prisma } from "../../../lib/prisma";

export const all = AstroAuth({
  authProviders: [
    CredentialProvider({
      authorize: async (properties) => {
        const account = await prisma?.account.findFirst({
          where: {
            username: properties.username,
            AND: {
              password: properties.password,
            },
          },
          select: {
            id: true,
          },
        });
        if (account?.id) {
          return properties.username;
        }
        return null;
      },
    }),
  ],
});

Creating a login page was very easy. I just created a form, calling the signIn() method from @astro-auth on submit, and BOOM: logged in! The code for the login page:

src/pages/login.astro
<html>
  <head>
    <title>Login</title>
    <script>
      import { signIn } from "@astro-auth/client";

      document.addEventListener("DOMContentLoaded", () => {
        document
          .querySelector("form")
          ?.addEventListener("submit", async (e) => {
            e.preventDefault();
            const form = e.target;
            if (form) {
              const formData = new FormData(form as HTMLFormElement);
              const data = Object.fromEntries(formData);
              await signIn({
                provider: "credential",
                login: data,
              });
              window.location.href = "/";
            }
          });
      });
    </script>
  </head>
  <body>
    <form>
      <label for="username">Name</label>
      <input type="text" name="username" />

      <label for="password">Password</label>
      <input type="password" name="password" />

      <input type="submit" value="Submit" />
    </form>
  </body>
</html>

After submitting the form, the user’s signed in and is redirected to the homepage. Protecting a page with authentication is easy, just checking the logged in user with the getUser() function from @astro-auth. Here’s an example of a page where I used this check:

src/pages/comment-overview.astro
---
import { getUser } from "@astro-auth/core";
import Layout from "../layouts/Layout.astro";
import { prisma } from "../lib/prisma";
import CommentsOverviewWrapper from "../components/CommentOverviewWrapper";
const user = getUser({ client: Astro });
if (!user) {
  return Astro.redirect("/", 307);
}
const commentsWithPost = await prisma?.comment.findMany({
  include: {
    post: {
      select: { url: true },
    },
  },
});
---

<Layout
  description="Overview of comments"
  title="Thomas Ledoux | Comment overview"
>
  <CommentsOverviewWrapper commentsWithPost={commentsWithPost} client:load />
</Layout>

If the user is not logged in, the user will be redirected to the homepage with a 307 status code. I also have an API route to delete comments on my blog posts, which I want to fence off so only authenticated user can use this API. It’s possible to use the getUser() function from @astro-auth for this too, but this time we’re going to pass the request instead of the Astro object. Example of using this code:

src/pages/api/comments.ts
export const del: APIRoute = async ({ request }) => {
  const user = getUser({ server: request });
  if (user) {
    const body = await request.json();
    const deleteComment = await prisma?.comment.delete({
      where: {
        id: body.id,
      },
    });
    return new Response(
      JSON.stringify({
        message: `Comment with id ${deleteComment?.id} deleted`,
      }),
      { status: 200 },
    );
  }
  return new Response(null, { status: 403 });
};

So when the user is not authenticated, a 403 response will be returned.

Hope this was helpful! Source code can be found on my Github as always.

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