Build and Deploy a GraphQL API to the Edge with Fauna — Part 6

In this step, we'll create a GraphQL mutation to delete products from the Fauna collection. To do this, update the grafbase/grafbase.config.ts file to include the following:

const productDeletePayload = g.type('ProductDeletePayload', {
  deleted: g.boolean()
})

g.mutation('productDelete', {
  args: {
    by: g.inputRef(productByInput)
  },
  resolver: 'products/delete',
  returns: g.ref(productDeletePayload).optional()
})

We don't need to add anything else to the configuration since we're reusing productByInput.

Now create the resolver file grafbase/resolvers/products/delete.ts and add the following:

import { Client, fql, FaunaError } from 'fauna'

const client = new Client()

export default async function ProductsDelete(_, { by }) {
  const { id } = by

  try {
    const documentQuery = fql`
      products.byId(${id}).delete()
    `

    await client.query(documentQuery)

    return { deleted: true }
  } catch (error) {
    if (error instanceof FaunaError) {
      console.log(error)
    }

    return { deleted: false }
  }
}

That's it! Fauna will throw an error if the document by ID does not exist. You can forward these errors on by doing something like this inside the catch block:

if (error instanceof FaunaError) {
  throw new GraphQLError(error?.message)
}

Open Pathfinder at http://127.0.0.1:4000 and execute the following GraphQL mutation:

mutation {
  productDelete(by: {
    id: "372397409740783822"
  }) {
    deleted
  }
}

You should now see something like this if the request was successful:

{
  "data": {
    "productDelete": {
      "deleted": true
    }
  }
}

That's it! You can now create, update and delete products inside the Fauna Database using GraphQL.

Continue to Part 7 👉