CODEWITHSUNDEEP
typescriptnext.js
asmodianis
asmodianis

Reputation: 1126

How to make Next.js getStaticProps work with typescript

I am using Next.js with typescript feature enabled

Trying to use getStaticProps as described here https://nextjs.org/docs/basic-features/typescript

With GetStaticProps type

export const getStaticProps: GetStaticProps = () => {
    return {
        props: {
            host: process.env.DB_HOST.toString(),
        },
    }
}

I am getting error like this enter image description here

Type '() => { props: { host: string; }; }' is not assignable to type 'GetStaticProps<{ [key: string]: any; }, ParsedUrlQuery>'.
  Type '{ props: { host: string; }; }' is missing the following properties from type 'Promise<GetStaticPropsResult<{ [key: string]: any; }>>': then, catch, [Symbol.toStringTag], finallyts(2322)

I would appreciate any help.

Here is the entire page's code:

import Head from 'next/head'
import styles from '../styles/Home.module.css'
import React from 'react'
import { GetStaticProps, GetStaticPropsContext } from 'next'

interface Props {
    host: string
}

const Home: React.FC<Props> = (props) => {
    return (
        <div className={styles.container}>
            <Head>
                <title>Create Next App</title>
                <link rel="icon" href="/favicon.ico" />
            </Head>

            <main className={styles.main}>
                aa:{props.host}
                <h1 className={styles.title}>
                    Welcome to <a href="https://nextjs.org">Next.js!</a>
                </h1>
                <p className={styles.description}>
                    Get started by editing <code className={styles.code}>pages/index.js</code>
                </p>
                <div className={styles.grid}>
                    <a href="https://nextjs.org/docs" className={styles.card}>
                        <h3>Documentation &rarr;</h3>
                        <p>Find in-depth information about Next.js features and API.</p>
                    </a>

                    <a href="https://nextjs.org/learn" className={styles.card}>
                        <h3>Learn &rarr;</h3>
                        <p>Learn about Next.js in an interactive course with quizzes!</p>
                    </a>

                    <a
                        href="https://github.com/vercel/next.js/tree/master/examples"
                        className={styles.card}
                    >
                        <h3>Examples &rarr;</h3>
                        <p>Discover and deploy boilerplate example Next.js projects.</p>
                    </a>

                    <a
                        href="https://vercel.com/import?filter=next.js&utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
                        className={styles.card}
                    >
                        <h3>Deploy &rarr;</h3>
                        <p>Instantly deploy your Next.js site to a public URL with Vercel.</p>
                    </a>
                </div>
            </main>

            <footer className={styles.footer}>
                <a
                    href="https://vercel.com?utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
                    target="_blank"
                    rel="noopener noreferrer"
                >
                    Powered by <img src="/vercel.svg" alt="Vercel Logo" className={styles.logo} />
                </a>
            </footer>
        </div>
    )
}

export const getStaticProps: GetStaticProps = () => {
    return {
        props: {
            host: process.env.DB_HOST.toString(),
        },
    }
}

export default Home

Upvotes: 83

Views: 103754

Answers (7)

Roman M. Koss
Roman M. Koss

Reputation: 999

Disclaimer: For /pages setup only

In short use this for constant reuse:


export const getStaticProps = async ({
    params,
}: GetStaticPropsContext<PageParams>): Promise<
    GetStaticPropsResult<ContentPageProps>
> => {
    const { title, description } = await fetch(".../entity", { uuid: params.uuid })
    return {
        props: {
            title,
            description,
        },
    }
}

Here is what correct typing for getStaticProps looks like in page/content.tsx for me:

import type {
    GetStaticPathsResult,
    GetStaticPropsContext,
    GetStaticPropsResult,
} from 'next'

type PageParams = {
   uuid: string
}

type ContentPageProps = {
   title: string
   description: string
}

const ContentPage = ({ title, description }: ContentPageProps): JSX.Element => {
    return (
        <>
             <h1>{title}</h1>
             <p>{description}</p>
        </>
    )
}

export default ContentPage

export const getStaticProps = async ({
    params,
}: GetStaticPropsContext<PageParams>): Promise<
    GetStaticPropsResult<ContentPageProps>
> => {
    const { title, description } = await fetch(".../entity", { uuid: params.uuid })
    return {
        props: {
            title,
            description,
        },
    }
}

export const getStaticPaths = async ({}): Promise<
    GetStaticPathsResult<PageParams>
> => {
    return {
        paths: { params: { uuid: "54b659a1-3f20-4440-90b5-9107bd62b5ca" }},
        fallback: false,
    }
}

Notice

async (context:GetStaticPropsContext<PageParams>):
    Promise<GetStaticPropsResult<ContentPageProps>

Where PageParams is derived from ParsedUrlQuery and ContentPageProps is what you will put into your component to render, can by any complexity (but not recursive).

Upvotes: 8

Bon Andre Opina
Bon Andre Opina

Reputation: 2228

Hi Ran in to your issue but none of the answers above helped me.

I had a quick read in the documentation: https://nextjs.org/docs/basic-features/data-fetching#getstaticprops-static-generation

and found out that you the correct type for your getStaticProps should be:

import { GetStaticProps } from 'next'

export const getStaticProps: GetStaticProps = async (context) => {
  // ...
}

Then in your component:

import { InferGetStaticPropsType } from 'next'
import { GetStaticProps } from 'next'

type Post = {
  author: string
  content: string
}

export const getStaticProps: GetStaticProps = async (context) => {
  const res = await fetch('https://.../posts')
  const posts: Post[] = await res.json()

  return {
    props: {
      posts,
    },
  }
}

function Blog({ posts }: InferGetStaticPropsType<typeof getStaticProps>) {
  // will resolve posts to type Post[]
}

export default Blog

This will autogenerate a type from GetStaticProps to your component it worked for me 100%

Upvotes: 84

Yilmaz
Yilmaz

Reputation: 49709

  • getStaticPaths

    export const getStaticPaths: GetStaticPaths = async () => {

  • getStaticProps

    export const getStaticProps = async ({params}: 
                                     GetStaticPropsContext<{ slug: string }>) => {

  • Component

     export default function Product({product}: InferGetStaticPropsType<typeof getStaticProps>) {

Upvotes: 1

Giuseppe Silvano
Giuseppe Silvano

Reputation: 151

The correct way to do it in 2022 is to leverage generics in the Next.js types.

import type { NextPage, GetStaticProps } from "next";
// ...

interface HomeProps {
  host: string
}

const Home: NextPage<HomeProps> = (props) => {
  // ...
};

export const getStaticProps: GetStaticProps<HomeProps> = async () => {
  // ...
};

Upvotes: 10

petrosmm
petrosmm

Reputation: 550

I had same trouble as OP. This tutorial worked perfectly for me: https://www.vitamindev.com/next-js/getstaticprops-getstaticpaths-typescript/. It addressed the issue where getStaticPaths requires a type of ParsedUrlQuery. Authors offers extending it, as a solution. Please make you name your properties exactly(!) else TS will complain.

Upvotes: 2

dmudro
dmudro

Reputation: 3104

Your original example is almost correct but the getStaticProps function expression is missing async. Try this:

export const getStaticProps: GetStaticProps = async () => { // must be async
  return {
    props: {
      host: process.env.DB_HOST.toString(),
    },
  };
};

This is not because of TS but the actual definition of getStaticProps() in Next.js.

Back to your example, even better would be to improve typing with the Props generic:

interface Props {
  host: string;
}

export const getStaticProps: GetStaticProps<Props> = async () => {
  return {
    props: {
      host: process.env.DB_HOST.toString(),
    },
  };
};

Upvotes: 27

asmodianis
asmodianis

Reputation: 1126

Answer is as follows:

export async function getStaticProps(context): Promise<GetStaticPropsResult<HomeProps>> {
    return {
        props: {
            host: process.env.DB_HOST,
        },
    };
}

My colleague found the solution by checking GetStaticProps type definition: enter image description here

Here is the whole page code

import Head from "next/head";
import styles from "../styles/Home.module.css";
import React from "react";
import { GetStaticPropsResult, GetStaticProps } from "next";

interface HomeProps {
    host: string;
}

const Home: React.FC<HomeProps> = (props: HomeProps) => {
    return (
        <div className={styles.container}>
            <Head>
                <title>Create Next App</title>
                <link rel="icon" href="/favicon.ico" />
            </Head>

            <main className={styles.main}>
                aa:{props.host}
                <h1 className={styles.title}>
                    Welcome to <a href="https://nextjs.org">Next.js!</a>
                </h1>
                <p className={styles.description}>
                    Get started by editing <code className={styles.code}>pages/index.js</code>
                </p>
                <div className={styles.grid}>
                    <a href="https://nextjs.org/docs" className={styles.card}>
                        <h3>Documentation &rarr;</h3>
                        <p>Find in-depth information about Next.js features and API.</p>
                    </a>

                    <a href="https://nextjs.org/learn" className={styles.card}>
                        <h3>Learn &rarr;</h3>
                        <p>Learn about Next.js in an interactive course with quizzes!</p>
                    </a>

                    <a href="https://github.com/vercel/next.js/tree/master/examples" className={styles.card}>
                        <h3>Examples &rarr;</h3>
                        <p>Discover and deploy boilerplate example Next.js projects.</p>
                    </a>

                    <a
                        href="https://vercel.com/import?filter=next.js&utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
                        className={styles.card}
                    >
                        <h3>Deploy &rarr;</h3>
                        <p>Instantly deploy your Next.js site to a public URL with Vercel.</p>
                    </a>
                </div>
            </main>

            <footer className={styles.footer}>
                <a
                    href="https://vercel.com?utm_source=create-next-app&utm_medium=default-template&utm_campaign=create-next-app"
                    target="_blank"
                    rel="noopener noreferrer"
                >
                    Powered by <img src="/vercel.svg" alt="Vercel Logo" className={styles.logo} />
                </a>
            </footer>
        </div>
    );
};

export async function getStaticProps(context): Promise<GetStaticPropsResult<HomeProps>> {
    return {
        props: {
            host: process.env.DB_HOST,
        },
    };
}

export default Home;

Upvotes: 17

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