section27 퀴즈 질문입니다.

등록 시 화면 페이지는 바뀌는데 바뀌자마자 위와 같은 오류가 떠서 계속 찾아보는데 혼자는 해결하기 어려워 여쭤봅니다 ㅠㅠ 어디가 틀린 걸까요? mutation은 제대로 된 걸 확인했는데 fetch가 안 되네요.

폴더 구조는

05/boards/new index.js

05/boards/products/[productId] index.js

import { useState } from "react";
import { useMutation, gql } from "@apollo/client";
import { useRouter } from "next/router";

const CREATE_PRODUCT = gql`
  mutation createProduct(
    $seller: String
    $createProductInput: CreateProductInput!
  ) {
    createProduct(seller: $seller, createProductInput: $createProductInput) {
      _id
      number
      message
    }
  }
`;

export default function ProductRegPage() {
  const router = useRouter();
  const [seller, setSeller] = useState();
  const [name, setName] = useState();
  const [detail, setDetail] = useState();
  const [price, setPrice] = useState();

  const [createProduct] = useMutation(CREATE_PRODUCT);

  const onClickRegister = async () => {
    try {
      const result = await createProduct({
        variables: {
          seller,
          createProductInput: {
            name,
            detail,
            price,
          },
        },
      });
      console.log(result);
      router.push(`/05/boards/products/${result.data.createProduct._id}`);
    } catch (error) {
      alert(error.message);
    }
  };

  const onChangeSeller = (event) => {
    setSeller(event.target.value);
  };

  const onChangeName = (event) => {
    setName(event.target.value);
  };

  const onChangeDetail = (event) => {
    setDetail(event.target.value);
  };

  const onChangePrice = (event) => {
    setPrice(parseInt(event.target.value));
  };

  return (
    <div>
      판매자: <input type="text" onChange={onChangeSeller} />
      상품명: <input type="text" onChange={onChangeName} />
      상품내용: <input type="text" onChange={onChangeDetail} />
      상품가격: <input type="text" onChange={onChangePrice} />
      <button onClick={onClickRegister}>상품 등록</button>
    </div>
  );
}

import { useQuery, gql } from "@apollo/client";
import { useRouter } from "next/router";

const FETCH_PRODUCT = gql`
  query fetchProduct($productId: ID) {
    fetchProduct(productId: $productId) {
      seller
      name
      detail
      price
    }
  }
`;

export default function ProductDetailPage() {
  const router = useRouter();
  console.log(router);

  const { data } = useQuery(FETCH_PRODUCT, {
    variables: { productId: router.query.productId },
  });

  console.log(data);

  return (
    <div>
      <div>판매자:{data ? fetchProduct?.seller : "loading..."}</div>
      <div>상품명:{data ? fetchProduct?.name : "loading..."}</div>
      <div>상품내용:{data ? fetchProduct?.detail : "loading..."}</div>
      <div>상품가격:{data ? fetchProduct?.price : "loading..."}</div>
    </div>
  );
}