Typing props from GetStaticProps

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To properly type the cityData in TypeScript, you need to define the shape of the data that getStaticProps is returning. In your case, it seems like trpcState is an object that contains a json property, which in turn contains a queries array. The first element of this array has a state object with a data property.

You can define an interface that describes this structure and use it to type your props. However, the extracts provided do not contain specific information about the structure of trpcState, so I can't provide an exact interface.

Here's a general example of how you could define the interface:

interface ITrpcState {
  json: {
    queries: Array<{
      state: {
        data: any; // Replace 'any' with the actual type of 'data'
      };
    }>;
  };
}

interface IProps {
  trpcState: ITrpcState;
  cityName: string;
}

const CityPage: NextPageWithLayout = (props: IProps) => {
  const cityData = props.trpcState.json.queries[0].state.data;
  // ...
};

In this example, replace any with the actual type of data. If you don't know the type of data, you might need to check the function or API that's providing the data.

Remember, TypeScript is all about defining the shape of your data. If you know the shape, you can create interfaces or types that describe your data and use them to avoid unsafe assignments.

For more information about typing in Next.js with TypeScript, you can refer to the Next.js Documentation (https://nextjs.org/docs/pages/building-your-application/configuring/typescript#static-generation-and-server-side-rendering).

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From the provided code, it seems like trpcState is the result of calling the dehydrate method on the object returned by generateSSGHelper(). However, the extracts do not provide specific information about the return type of generateSSGHelper() or the dehydrate method, so it's not possible to provide an exact TypeScript type for trpcState.

However, if you have access to the type definitions of the library that provides createServerSideHelpers, you can use those to infer the type of trpcState. For example, if createServerSideHelpers is a function from the trpc library, and it returns an object with a dehydrate method that returns a DehydratedState object, you could do:

import { DehydratedState } from '@trpc/server';

interface IProps {
  trpcState: DehydratedState;
  cityName: string;
}

const CityPage: NextPageWithLayout = (props: IProps) => {
  const cityData = props.trpcState.json.queries[0].state.data;
  // ...
};

Please replace @trpc/server and DehydratedState with the actual module and type if they're different. If you're unsure, you might need to check the documentation or type definitions of the library that provides createServerSideHelpers.

For more information about typing in Next.js with TypeScript, you can refer to the Next.js Documentation (https://nextjs.org/docs/pages/building-your-application/configuring/typescript#static-generation-and-server-side-rendering).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@obtuse heart kapa.ai is still learning and improving, please let us know how it did by reacting below

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Let me check the knowledge base for you. One moment! :books:

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The createServerSideHelpers function from @trpc/react-query/server is used to create server-side helpers for tRPC. The return type of this function is CreateSSGHelpersResult.

You can import this type from @trpc/react-query/server and use it to type the return value of your generateSSGHelper function:

import { createServerSideHelpers, CreateSSGHelpersResult } from "@trpc/react-query/server";
import { appRouter } from "~/server/api/root";
import { prisma } from "~/server/db";
import superjson from "superjson";

export const generateSSGHelper = (): CreateSSGHelpersResult => {
  return createServerSideHelpers({
    router: appRouter,
    ctx: { prisma, userId: null },
    transformer: superjson, // optional - adds superjson serialization
  });
};

Now, you can use the CreateSSGHelpersResult type to infer the type of trpcState in your getStaticProps function:

import { InferGetStaticPropsType, GetStaticProps } from 'next';
import { CreateSSGHelpersResult } from "@trpc/react-query/server";

export const getStaticProps: GetStaticProps = async (context) => {
  const ssg = generateSSGHelper();
  const slug = context.params?.slug;
  if (typeof slug !== "string") throw new Error("no slug");
  const cityName = slug.replace("@", "");
  await ssg.city.getCityDataByName.prefetch({ name: cityName });

  return {
    props: {
      trpcState: ssg.dehydrate(),
      cityName,
    },
  };
};

type CityPageProps = InferGetStaticPropsType<typeof getStaticProps> & {
  trpcState: CreateSSGHelpersResult['dehydrate'];
};

const CityPage: NextPageWithLayout<CityPageProps> = (props) => {
  const cityData = props.trpcState.json.queries[0].state.data;
  // ...
};

Please note that the exact type of trpcState might be different depending on the actual implementation of createServerSideHelpers and dehydrate. If you're unsure, you might need to check the documentation or type definitions of the @trpc/react-query/server library.

For more information about typing in Next.js with TypeScript, you can refer to the Next.js Documentation (https://nextjs.org/docs/pages/building-your-application/configuring/typescript#static-generation-and-server-side-rendering).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: