Creating a serverless GraphQL API with TypeScript and Prisma

This was originally posted in my blog on 6th December 2020.

In this post we'll create a GraphQL API to create, view and delete notes that we can deploy to Vercel using Apollo Server, TypeScript and MongoDB.

Initial Setup

First Vercel will need be downloaded, installed and logged into.

yarn global add vercel
vercel login

The nice thing about using Vercel for development is that we don't have to worry about manually configuring TypeScript.

Then create a folder, initialize a project in it and install typescript as a dev dependency.

mkdir serverless-api-graphql-prisma
cd serverless-api-graphql-prisma
yarn init --yes
yarn add typescript -D

Setup the Database

We will be using Prisma to connect to and work with our database. In this example we'll be using PostgreSQL.

If you need a database without installing one locally, Heroku has free tier.

Once you have the database set up, keep note of its URL.

Setup Prisma

First install the dependencies.

yarn add @prisma/cli ts-node @types/node -D

Then create tsconfig.json with the following configuration.

{
  "compilerOptions": {
    "sourceMap": true,
    "outDir": "dist",
    "strict": true,
    "lib": ["esnext"],
    "esModuleInterop": true
  }
}

Next let's create the Prisma schema file by running the prisma init command.

npx prisma init

This will create the prisma folder in the project root and in it the schema.prisma and .env files.

// This is your Prisma schema file,
// learn more about it in the docs: https://pris.ly/d/prisma-schema

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

generator client {
  provider = "prisma-client-js"
}

# Environment variables declared in this file are automatically made available to Prisma.
# See the documentation for more detail: https://pris.ly/d/prisma-schema#using-environment-variables

# Prisma supports the native connection string format for PostgreSQL, MySQL and SQLite.
# See the documentation for all the connection string options: https://pris.ly/d/connection-strings

DATABASE_URL="postgresql://johndoe:randompassword@localhost:5432/mydb?schema=public"

Replace the placeholder DATABASE_URL in your .env file with the URL of your own database.

Remember to not commit the .env file. Add it to .gitignore.

To organize our code, first let's move the .env to the project root.

Then move the schema.prisma file to src\db\schema.prisma.

// src\db\schema.prisma
// This is your Prisma schema file,
// learn more about it in the docs: https://pris.ly/d/prisma-schema

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

generator client {
  provider = "prisma-client-js"
}

We also need to modify Prisma to read the schema from its new path by adding the path in package.json.

{
  "prisma": {
    "schema": "src/db/schema.prisma"
  }
}

Now we need to add the model for Notes. All models are "declared" in the schema.prisma file.

// src\db\schema.prisma
// This is your Prisma schema file,
// learn more about it in the docs: https://pris.ly/d/prisma-schema

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

generator client {
  provider = "prisma-client-js"
}

model Note {
  id      Int      @id @default(autoincrement())
  date    DateTime @default(now())
  title   String
  content String
}

Creating the database tables

We will be using Prisma Migrate to create the database tables using the models in your schema file.

First enter the following command.

npx prisma migrate save --name init --experimental

This will create a new folder called migrations in src\db to store your migration history but it won't actually create the table in your database.

Replace init with the name of your migration.

To finish creating the table, run the up command.

npx prisma migrate up --experimental

Install and Generate the Prisma Client

yarn add @prisma/client
npx prisma generate

When you generate the Prisma Client it will create types for all the database models to use in our code. In our case it'll create one for Note.

Setup the GraphQL API

First let's install the dependencies.

yarn add apollo-server-micro graphql graphql-iso-date
yarn add @types/graphql-iso-date -D

Next create the folder api in the project root and in it create the file graphql.ts. Vercel will expose the serverless function in the file as the endpoint /api/graphql. The GraphQL function will be created using Apollo Server. Since we're doing a serverless version we'll be using apollo-server-micro.

Then import ApolloServer from apollo-server-micro.

// api/graphql.ts
import { ApolloServer } from "apollo-server-micro";

After that import the GraphQL Schemas and Resolvers. We'll create these later.

// api/graphql.ts
import { ApolloServer } from "apollo-server-micro";

import typeDefs from "../src/graphql/schema";
import resolvers from "../src/graphql/resolvers";

Then initialize the Apollo Server and export it.

// api/graphql.ts
import { ApolloServer } from "apollo-server-micro";

import typeDefs from "../src/graphql/schema";
import resolvers from "../src/graphql/resolvers";

const apolloServer = new ApolloServer({
  typeDefs,
  resolvers,
});

export default apolloServer.createHandler({ path: "/api/graphql" });

To finish configuring we'll set the introspection and playground options.

// api/graphql.ts
import { ApolloServer } from "apollo-server-micro";

import typeDefs from "../src/graphql/schema";
import resolvers from "../src/graphql/resolvers";

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

export default apolloServer.createHandler({ path: "/api/graphql" });

Setup the GraphQL Schema

In the src folder create the graphql folder and in it create the schema folder.

GraphQL doesn't have a type for date and time so we'll need a schema for those types. Create custom.ts in the schema folder.

// src/graphql/schema/custom.ts
import { gql } from "apollo-server-micro";

export default gql`
  scalar Date
  scalar Time
  scalar DateTime
`;

Next we'll setup the schema for Note.

First create the Note schema file, note.ts in the schema folder.

// src/graphql/schema/note.ts
import { gql } from "apollo-server-micro";

export default gql``;

Then add the Note type.

// src/graphql/schema/note.ts
import { gql } from "apollo-server-micro";

export default gql`
  type Note {
    id: ID!
    title: String!
    content: String!
    date: DateTime!
  }
`;

After that add two Queries, one to get all Notes and one to get a specific Note.

// src/graphql/schema/note.ts
import { gql } from "apollo-server-micro";

export default gql`
  extend type Query {
    getAllNotes: [Note!]
    getNote(id: ID!): Note
  }

  type Note {
    id: ID!
    title: String!
    content: String!
    date: DateTime!
  }
`;

Next add two Mutations to create new Notes and delete existing ones.

// src/graphql/schema/note.ts
import { gql } from "apollo-server-micro";

export default gql`
  extend type Query {
    getAllNotes: [Note!]
    getNote(id: ID!): Note
  }

  extend type Mutation {
    saveNote(title: String!, content: String!): Note!
    deleteNote(id: ID!): Note
  }

  type Note {
    id: ID!
    title: String!
    content: String!
    date: DateTime!
  }
`;

Note that we add the keyword extend to the Query and Mutation type in the two schemas. This is because we'll be joining all the schemas into one later.

Finally we'll need a schema a join all the others schemas together. Create index.ts in the schema folder and declare and export the Link Schema in an array.

// src/graphql/schema/index.ts
import { gql } from "apollo-server-micro";

const linkSchema = gql`
  type Query {
    _: Boolean
  }

  type Mutation {
    _: Boolean
  }

  type Subscription {
    _: Boolean
  }
`;

export default [linkSchema];

Then import the other Schemas and add them to the array.

// src/graphql/schema/index.ts
import { gql } from "apollo-server-micro";

import noteSchema from "./note";
import customSchema from "./custom";

const linkSchema = gql`
  type Query {
    _: Boolean
  }

  type Mutation {
    _: Boolean
  }

  type Subscription {
    _: Boolean
  }
`;

export default [linkSchema, noteSchema, customSchema];

Setup the resolvers

Since we added a custom type for dates and times in our schema, the first resolver we'll add is for those types. Create a folder called resolvers in the graphql folder and in it create custom.ts.

// src/graphql/resolvers/custom.ts
import { GraphQLDate, GraphQLTime, GraphQLDateTime } from "graphql-iso-date";

export default {
  Date: GraphQLDate,
  Time: GraphQLTime,
  DateTime: GraphQLDateTime,
};

Next we'll start working on the resolver for Notes.

Start by creating note.ts in graphql, importing the required dependencies and exporting an empty object which is going to be our resolver.

// src/graphql/resolvers/note.ts
import { ApolloError } from "apollo-server-micro";
import { PrismaClient, Note } from "@prisma/client";

const prisma = new PrismaClient();

export default {};

Notice the Note type from @prisma/client this comes from generating the Prisma Client from earlier.

Then define an object for the Queries.

// src/graphql/resolvers/note.ts
// ...

export default {
  Query: {},
};

When defining the function for each of the queries (or mutations or fields) there are three important parameters.

• parent - If you a resolving a field of an object this parameter will contain it. We won't be needing it in this post.
• args - The arguments passed to the query or mutation.
• context - The context object created when setting up the API. We won't be needing it in this post.

First let's write the resolver for getAllNotes. Start by declaring the function.

// src/graphql/resolvers/note.ts
// ...

export default {
  Query: {
    getAllNotes: async (): Promise<Note[]> => {},
  },
};

Then add the code to get all the notes.

// src/graphql/resolvers/note.ts
// ...

export default {
  Query: {
    getAllNotes: async (): Promise<Note[]> => {
      try {
        const notes = await prisma.note.findMany();

        return notes;
      } catch (error) {
        console.error("> getAllNotes error: ", error);

        throw new ApolloError("Error retrieving all notes");
      }
    },
  },
};

After that let's add the resolver for getNote.

// src/graphql/resolvers/note.ts {20-37}
// ...

export default {
  Query: {
    // ... 

    getNote: async (
      parent: any,
      { id }: { id: Note["id"] }
    ): Promise<Note | null> => {
      try {
        const note = await prisma.note.findUnique({
          where: {
            id,
          },
        });

        return note;
      } catch (error) {
        console.error("> getNote error: ", error);

        throw new ApolloError("Error retrieving note");
      }
    },
  },
};

We can retrieve the id argument from the second parameter.

Let's finish of the Note resolvers by adding the resolvers for the mutations.

// src/graphql/resolvers/note.ts
// ...
export default {
  // ...

  Mutation: {
    saveNote: async (
      parent: any,
      { title, content }: { title: Note["title"]; content: Note["content"] }
    ): Promise<Note> => {
      try {
        const note = await prisma.note.create({
          data: {
            title,
            content,
          },
        });

        return note;
      } catch (error) {
        console.error("> saveNote error: ", error);

        throw new ApolloError("Error creating note");
      }
    },

    deleteNote: async (
      parent: any,
      { id }: { id: Note["id"] }
    ): Promise<Note> => {
      try {
        const note = await prisma.note.delete({
          where: {
            id,
          },
        });

        return note;
      } catch (error) {
        console.error("> getNote error: ", error);

        throw new ApolloError("Error retrieving all notes");
      }
    },
  },
};

In the end the file should look like this.

import { ApolloError } from "apollo-server-micro";
import { PrismaClient, Note } from "@prisma/client";

const prisma = new PrismaClient();

export default {
  Query: {
    getAllNotes: async (): Promise<Note[]> => {
      try {
        const notes = await prisma.note.findMany();

        return notes;
      } catch (error) {
        console.error("> getAllNotes error: ", error);

        throw new ApolloError("Error retrieving all notes");
      }
    },

    getNote: async (
      parent: any,
      { id }: { id: Note["id"] }
    ): Promise<Note | null> => {
      try {
        const note = await prisma.note.findUnique({
          where: {
            id,
          },
        });

        return note;
      } catch (error) {
        console.error("> getNote error: ", error);

        throw new ApolloError("Error retrieving note");
      }
    },
  },

  Mutation: {
    saveNote: async (
      parent: any,
      { title, content }: { title: Note["title"]; content: Note["content"] }
    ): Promise<Note> => {
      try {
        const note = await prisma.note.create({
          data: {
            title,
            content,
          },
        });

        return note;
      } catch (error) {
        console.error("> saveNote error: ", error);

        throw new ApolloError("Error creating note");
      }
    },

    deleteNote: async (
      parent: any,
      { id }: { id: Note["id"] }
    ): Promise<Note> => {
      try {
        const note = await prisma.note.delete({
          where: {
            id,
          },
        });

        return note;
      } catch (error) {
        console.error("> getNote error: ", error);

        throw new ApolloError("Error retrieving all notes");
      }
    },
  },
};

Now we have to connect all the resolvers together using an index.ts file created in the resolvers folder.

// src/graphql/resolvers/index.ts
import noteResolver from "./note";
import customResolver from "./custom";

export default [noteResolver, customResolver];

Running the API locally

To run the project locally first you need to link it to a Vercel project.

vercel link

Then run vercel dev to start the API locally.

vercel dev

If you visit http://localhost:3000/api/graphql you can see the GraphQL Playground.

Deploying to Vercel

First we need to upload the database path as an Environment Variable.

vercel env add

Name the variable DB_PATH and make sure you make to available for all three environments (Production, Preview and Development).

Then all that's left to do is to deploy to Vercel.

vercel

The GraphQL Playground should be visible in the /api/graphql route of the URL returned.

Wrapping Up

I made a sample deployment which you can check out here. The source code is available on GitHub.

If you want a more detailed explanation into GraphQL and making a server for it, you can check out the excellent guide that I learnt from here.

Bonus: Using it in Next.js

You can create a GraphQL API endpoint in your Next.js project by putting the graphql.ts inside the api folder in the pages folder.

The only extra step you need to do is to add this bit of code to the end of the graphql.ts file.

// pages/api/graphql.ts
// ...

export default apolloServer.createHandler({ path: "/api/graphql" });

export const config = {
  api: {
    bodyParser: false,
  },
};