Developers strive to create efficient, scalable, and maintainable web applications. To achieve this, they often use modern web technologies, such as TypeScript and GraphQL. In this article, we will discuss how to implement TypeScript and GraphQL in a Next.js web application.
Next.js is a popular React framework that allows developers to build server-side rendered (SSR) applications easily. It provides features such as automatic code splitting, server-side rendering, and static site generation. Next.js applications can also be easily deployed to the cloud.
TypeScript is a superset of JavaScript that adds static typing, classes, and interfaces to the language. It helps developers catch errors early in the development process and provides better code editor support. TypeScript code is transpiled to JavaScript, which can run in any browser.
GraphQL is a query language for APIs that allows clients to specify exactly what data they need from the server. It provides a more efficient and flexible alternative to traditional REST APIs. With GraphQL, clients can fetch multiple resources in a single request, reducing network overhead.
To set up a Next.js app with TypeScript, we need to install the required dependencies. We can use the following command to create a new Next.js app with TypeScript:
npx create-next-app --typescript my-app
This command creates a new Next.js app with TypeScript support. We can run the app using the following command:
cd my-app
npm run dev
We can now open the app in our browser at http://localhost:3000
.
To add GraphQL to a Next.js app, we need to install the following dependencies:
npm install graphql apollo-server-micro apollo-boost isomorphic-unfetch
graphql
: The GraphQL runtime library.apollo-server-micro
: A lightweight GraphQL server for Next.js.apollo-boost
: A package that provides a simple way to set up a GraphQL client.isomorphic-unfetch
: A package that provides a simple way to make HTTP requests from both the server and client.Next.js provides a built-in API route feature that allows us to create serverless functions. We can use this feature to create a GraphQL server.
Create a new file api/graphql.ts
with the following code:
import { ApolloServer, gql } from "apollo-server-micro";
import { NextApiRequest, NextApiResponse } from "next";
import fetch from "isomorphic-unfetch";
const typeDefs = gql`
type Query {
hello: String
}
`;
const resolvers = {
Query: {
hello: () => "Hello world!",
},
};
const apolloServer = new ApolloServer({
typeDefs,
resolvers,
context: async ({ req }: { req: NextApiRequest }) => {
const token = req.headers.authorization || "";
const user = await fetch("https://api.example.com/user", {
headers: { authorization: token },
}).then((res) => res.json());
return { user };
},
});
export const config = {
api: {
bodyParser: false,
},
};
export default apolloServer.createHandler({ path: "/api/graphql" });
In this code, we define a simple GraphQL schema with a single query hello
. We also define a resolver for the query that returns the string "Hello world!".
We then create an instance of ApolloServer
with the schema and resolvers. We also define a context function that fetches the user object from an external API using the authorization token in the request headers.
Finally, we export a Next.js API route with the GraphQL server handler. We also disable the default body parser in the API route configuration since Apollo Server already parses the request body.
To set up a GraphQL client, we can use the apollo-boost
package. Create a new file lib/apollo.ts
with the following code:
import { ApolloClient, InMemoryCache } from "apollo-boost";
export const client = new ApolloClient({
uri: "/api/graphql",
cache: new InMemoryCache(),
});
In this code, we create a new instance of ApolloClient
with the GraphQL server endpoint (/api/graphql
) and an in-memory cache.
Now that we have set up a Next.js app with TypeScript and added a GraphQL server and client, we can use them in our application.
To define a GraphQL query, we need to create a .graphql
file with the query definition. Create a new file queries/hello.graphql
with the following code:
query Hello {
hello
}
In this code, we define a GraphQL query Hello
with a single field hello
.
To use the GraphQL client in a component, we can use the useQuery
hook from the @apollo/react-hooks
package.
Create a new file pages/index.tsx
with the following code:
import { NextPage } from "next";
import { useQuery } from "@apollo/react-hooks";
import { client } from "../lib/apollo";
import HELLO_QUERY from "../queries/hello.graphql";
interface HelloData {
hello: string;
}
const IndexPage: NextPage = () => {
const { loading, error, data } = useQuery<HelloData>(HELLO_QUERY, {
client,
});
if (loading) return <p>Loading...</p>;
if (error) return <p>Error: {error.message}</p>;
return <p>{data?.hello}</p>;
};
export default IndexPage;
In this code, we import the useQuery
hook and the client
instance from lib/apollo
. We also import the HELLO_QUERY
GraphQL query from the queries/hello.graphql
file.
We define an interface HelloData
that represents the shape of the data returned by the query.
We then use the useQuery
hook to fetch the data from the server. We pass the HELLO_QUERY
and client
as arguments to the hook. We also provide a loading and error state while the query is being executed.
Finally, we render the data.hello
string if the query is successful.
In this article, we discussed how to implement TypeScript and GraphQL in a Next.js web application. We set up a GraphQL server and client and used them in a component to fetch data from the server. We hope this article has been helpful in your development journey.