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Overview

The @blitzjs/next adapter exposes functions & components specific for the Next.js framework.

Setup

You can install @blitzjs/next by running the following command:

npm i @blitzjs/next # yarn add @blitzjs/next # pnpm add @blitzjs/next

Next Config

Blitz.js extends the next.config.js file by accepting a blitz property.

blitz?: {
  resolverPath?: ResolverPathOptions;
  customServer?: {
      hotReload?: boolean;
  };
};

Client

Example

Inside src/blitz-client.ts:

import {setupBlitzClient} from "@blitzjs/next"

export const {withBlitz} = setupBlitzClient({
  plugins: [],
})

Then inside src/pages/_app.tsx wrap MyApp function with the withBlitz HOC component.

import {ErrorFallbackProps, ErrorComponent, ErrorBoundary} from "@blitzjs/next"
import {AuthenticationError, AuthorizationError} from "blitz"
import type {AppProps} from "next/app"
import React, {Suspense} from "react"
import {withBlitz} from "src/blitz-client"

function RootErrorFallback({error}: ErrorFallbackProps) {
  if (error instanceof AuthenticationError) {
    return <div>Error: You are not authenticated</div>
  } else if (error instanceof AuthorizationError) {
    return (
      <ErrorComponent
        statusCode={error.statusCode}
        title="Sorry, you are not authorized to access this"
      />
    )
  } else {
    return (
      <ErrorComponent
        statusCode={(error as any)?.statusCode || 400}
        title={error.message || error.name}
      />
    )
  }
}

function MyApp({Component, pageProps}: AppProps) {
  return (
    <ErrorBoundary FallbackComponent={RootErrorFallback}>
      <Component {...pageProps} />
    </ErrorBoundary>
  )
}

export default withBlitz(MyApp)

API

setupBlitzClient({
  plugins: [],
})

Arguments

• plugins: An array of Blitz.js plugins
  • Required

Returns

An object with the withBlitz HOC wrapper

Server

Example

Inside src/blitz-server.ts

import {setupBlitzServer} from "@blitzjs/next"

export const {gSSP, gSP, api} = setupBlitzServer({
  plugins: [],
})

API

setupBlitzServer({
  plugins: [],
  onError?: (err) => void
})

Arguments

• plugins: An array of Blitz.js plugins
  • Required
• onError: Catch all errors (Great for services like sentry)

Returns

An object with the gSSP, gSP & api wrappers.

Custom Server

The Blitz CLI supports running custom Next.js servers. This means you can compile both javascript & typescript while using the Blitz.js CLI to inject env variables. By default, the CLI checks for src/server/index.[ts | js] or src/server.[ts | js]

For more information about custom Next.js servers, check the official docs

Wrappers

All Next.js wrapper functions are serialized with superjson. That means you can use Date, Map, Set & BigInt when returning data. Another thing to note is that Blitz runs the middlewares from plugins before calling the Next.js request handler.

Examples

getStaticProps

import {gSP} from "src/blitz-server"

export const getStaticProps = gSP(async ({ctx}) => {
  return {
    props: {
      data: {
        userId: ctx?.session.userId,
        session: {
          id: ctx?.session.userId,
          publicData: ctx?.session.$publicData,
        },
      },
    },
  }
})

getServerSideProps

import {gSSP} from "src/blitz-server"

export const getServerSideProps = gSSP(async ({ctx}) => {
  return {
    props: {
      userId: ctx?.session.userId,
      publicData: ctx?.session.$publicData,
    },
  }
})

api

import {api} from "src/blitz-server"

export default api(async (req, res, ctx) => {
  res.status(200).json({userId: ctx?.session.userId})
})

For more information about Next.js API routes, visit their docs at https://nextjs.org/docs/api-routes/introduction

Concepts

Authenticate user before page loads

You may want to check if the user is logged in before your page loads. We’re going to use the getCurrentUser query inside getServerSideProps() by calling the query directly. Then you can check if the user is logged in on the server and use the built-in Next.js redirect property.

import {Routes, BlitzPage} from "@blitzjs/next"
import {gSSP} from "src/blitz-server"
import getCurrentUser from "src/users/queries/getCurrentUser"

export const getServerSideProps = gSSP(async ({ctx}) => {
  const currentUser = await getCurrentUser(null, ctx)

  if (currentUser) {
    return {
      props: {
        user: currentUser,
      },
    }
  } else {
    return {
      redirect: {
        destination: Routes.LoginPage(),
        permanent: false,
      },
    }
  }
})

Return types when data fetching on the server

You can set the types returned from the Next.js data fetching functions. All Blitz.js wrappers for the Next.js functions accept a generic. Same with the BlitzPage type.

So for example, we can use some typescript utilities to help use get the types returned by getCurrentUser()

import {Routes, BlitzPage} from "@blitzjs/next"
import {gSSP} from "src/blitz-server"
import getCurrentUser from "src/users/queries/getCurrentUser"

type TCurrentUser = Awaited<ReturnType<typeof getCurrentUser>>

export const getServerSideProps = gSSP<{user: TCurrentUser}>(async ({ctx}) => {
  const currentUser = await getCurrentUser(null, ctx)

  if (currentUser) {
    return {
      props: {
        user: currentUser,
      },
    }
  } else {
    return {
      redirect: {
        destination: Routes.LoginPage(),
        permanent: false,
      },
    }
  }
})

const Page: BlitzPage<{user: TCurrentUser}> = ({user}) => {
  return (
    <Layout title="Page">
      <div className="container">
        <p>User Page</p>
        {user && <p>{user.email}</p>}
      </div>
    </Layout>
  )
}

export default Page

Handling errors on initial page load

There’s an edge case where you may be throwing an error in a query that’s being called on an initial page load, causing a server error instead of hitting the <ErrorBoundary />. This is because when initially loading the page, there is no ErrorBoundary component rendered until _app.tsx is mounted. Though, this is expected behaviour, there is a workaround.

For an example, in a query where the user is not found you can create a NotFoundError() then return the status code.

export default resolver.pipe(resolver.zod(GetUser), async (input) => {
  const {id} = input

  const user = await db.user.findFirst({where: {id}})

  if (!user) {
    const userError = new NotFoundError("User not found")
    return {
      error: userError.statusCode,
    }
  } else {
    return {
      user,
    }
  }
})

Then on the server (in this case getServerSideProps()) you can call the query and if the error key is found in the return object then show an error.

export const getServerSideProps = gSSP(async ({ ctx }) => {

  const user = await getUser({ 1 }, ctx)
  if("error" in user) {
    return { props: { error: user.error}}
  } else {
    return { props: { user }}
  }
})

You can also catch server errors in _app.tsx and show the errors with a toast component.

function MyApp({Component, pageProps}: AppProps) {
  const getLayout = Component.getLayout || ((page) => page)
  if (pageProps.error) {
    return <ToastComponent>{pageProps.error.statusCode}</ToastComponent>
  }
  return (
    <ErrorBoundary FallbackComponent={RootErrorFallback}>
      {getLayout(<Component {...pageProps} />)}
    </ErrorBoundary>
  )
}