How to add a Graphql endpoint into a Sveltekit app

Warning: The code provided in this post is not well tested for every environment, and may not provide all the features, use with caution.

Hello, In this post I will show you how you can add a graphql endpoint in a sveltekit app with apollo-server-lambda.

TLDR;

If you want to start quickly, here's the boilerplate Repo: https://github.com/vibhanshu909/sveltekit-with-graphql

Note: I'm using typescript here, if you don't use typescript, make the required changes.
This Project also uses tailwindcss, if you don't want to use tailwindcss, perform the following steps.

• Delete postcss.config.cjs, tailwindcss.config.cjs & src/app.css files.
• remove postcss: true option in preprocess function from svelte.config.js file.
• remove import '../app.css'; statement from the script block in __layout.svelte file.

Follow the below steps.

Step 1: Install the required dependencies

npm i apollo-server-lambda graphql

Step 2: create a file src/routes/graphql.ts with the following contents.

import type { EndpointOutput, RequestHandler } from '@sveltejs/kit';
import { ApolloServer, gql } from 'apollo-server-lambda';

const typeDefs = gql`
    type Query {
        hello: String
    }
    type Mutation {
        double(x: Int!): Int!
    }
`;

// Provide resolver functions for your schema fields
const resolvers = {
    Query: {
        hello: () => 'Hello world!'
    },
    Mutation: {
        double: (_, { x }) => x * 2
    }
};

const apolloServer = new ApolloServer({
    typeDefs,
    resolvers,
    playground: true,
    introspection: true,
    tracing: true
});

const graphqlHandler = apolloServer.createHandler();

// This is where the magic happens.
const handler: RequestHandler = async (args) => {
    return await new Promise<EndpointOutput>((resolve, reject) => {
        graphqlHandler(
            {
                httpMethod: args.method,
                headers: args.headers,
                path: args.path,
                body: args.rawBody as string
            } as any,
            {} as any,
            (err, result) => {
                if (err) {
                    reject(err);
                } else {
                    resolve({
                        status: result.statusCode,
                        body: result.body,
                        headers: result.headers as any
                    });
                }
            }
        ) as any;
    });
};

export const head = handler;
export const get = handler;
export const post = handler;

Step 3: Test the endpoint.

npm run dev

Goto http://localhost:3000/graphql, you should see the graphql playground.

And that's it. :)

Comment down below, if you have any questions.

Comments

[Jonathan Gamble]

This does not work with SvelteKit.

I got mine to work with this:

const handler = async ({ request }) => {

  const r = await request.json();

  return {
    body: await server.executeOperation(r)
  };

}

export const head = handler;
export const get = handler;
export const post = handler;

[vibhanshu pandey]

Yes, Unfortunately this no longer works, there's been a number of updates in the sveltekit repo.

Thinking of Archiving this, until further updates.