Cloudflare Workers quick start

npm install -g wrangler@latest
npm create cloudflare my-fauna-worker -- \
  --category hello-world \
  --type hello-world \
  --lang ts \
  --git false \
  --deploy true
cd my-fauna-worker
npm install fauna

import { Client, fql, FaunaError, ServiceError } from "fauna";

// This interface defines the structure of the environment
// variables that get passed in.
export interface Env {
  FAUNA_SECRET: string;
}

export default {
  async fetch(request, env, ctx): Promise<Response> {
    // 1. Initialize a Fauna client using the FAUNA_SECRET env var.
    const client = new Client({ secret: env.FAUNA_SECRET });

    // Extract the email from the query string. Otherwise, use an
    // email address that's in the Fauna sample data.
    const url = new URL(request.url);
    const email =
      url.searchParams.get("email")
        || "alice.appleseed@example.com";

    try {
      // 2. Execute an FQL query to retrieve data from Fauna.
      //    In this example, it queries 'Customer.byEmail(...)' for
      //    a particular user. 'first()' ensures only the first
      //    matching result is returned as email has a unique
      //    constraint on it in this collection.
      const getData = await client.query(
        fql`Customer.byEmail(${email}).first()`
      );

      // 3. Return the retrieved data as a JSON response.
      return new Response(
        JSON.stringify(getData),
        { status: 200 }
      );
    } catch (error) {
      // 4. Handle Fauna-specific errors separately from
      //    other errors.
      if (error instanceof FaunaError) {
        // If it's a service error (e.g., a problem with the
        // query or the Fauna service itself), log the Fauna
        // queryInfo summary to the console for debugging.
        if (error instanceof ServiceError) {
          console.error(error.queryInfo?.summary);
        } else {
          // Otherwise, return a generic error response for
          // Fauna errors.
          return new Response(
            "Error " + error,
            { status: 500 }
          );
        }
      }
      // 5. For any other error, return a less specific
      //    message to prevent leaking internal error
      //    details to the caller.
      return new Response(
        "An error occurred, " +
        error.message, {
        status: 500,
      });
    }
  },
} satisfies ExportedHandler<Env>;