『TypeError: Cannot read properties of undefined (reading 'filter')』 エラーを改善したい

Question

ReactでMaterial-UI を使用して、Web フォームを作成しています。

『TypeError: Cannot read properties of undefined (reading 'filter')』　　src/components/Questionnaire.js:24
21 | <div>
22 | <p>Questionnaire</p>
23 | <Optional />
24 | ◉ <FormControl component="fieldset">
25 | 　　　　　　 {answers
26 | .filter((_, i) => i === 0 || answers[i - 1])
27 | .map((answer, i) => (

というエラーの表示が出て、どのように実装したら良いかわからない状況で、詰まっています。 何方かアドバイスをお願いします。
期待する動作
『TypeError: Cannot read properties of undefined (reading 'filter')』　　src/components/Questionnaire.js:24を改善したい
問題解決のため行ったこと
useContextを使用して、Confirm.js　に基本情報入力及び質問の回答を確認画面に表示するように実装したら、エラーが出た。

App.js

import "./App.css";
import { Grid } from "@mui/material";
import Header from "./components/Header";
import Content from "./components/Content";

function App() {
  return (
    <Grid container direction="column">
      <Header />
      <div style={{ padding: 30 }}>
        <Content />
      </div>
    </Grid>
  );
}
export default App;

src / components / contents.js

import React from "react";
import { Grid } from "@mui/material";
import Stepper from "@mui/material/Stepper";
import Step from "@mui/material/Step";
import StepLabel from "@mui/material/StepLabel";
import Button from "@mui/material/Button";
import Typography from "@mui/material/Typography";
import Basic from "./Basic";
import Questionnaire, { QUESTIONS } from "./Questionnaire";
import Optional from "./Optional";
import Confirm from "./Confirm";

unction getSteps() {
  return ["お客様の情報を入力して下さい", "以下にお答え下さい", "ご相談下さい", "以下の内容をご確認下さい"];
}
const StepContent = ({ stepIndex, questionnaireProps }) => {
  switch (stepIndex) {
    case 0:
      return <Basic />;
case 1:
      return <Questionnaire {...questionnaireProps} />;
    case 2:
      return <Optional />;
case 3:
      return <Confirm />;
    default:
      return "Unknown stepIndex";
  }
};
function Content() {
  const [activeStep, setActiveStep] = React.useState(0);
  const [answers, setAnswers] = React.useState(Array(QUESTIONS.length).fill(null));
  const steps = getSteps();
  const handleNext = () => {
    setActiveStep((prevActiveStep) => prevActiveStep + 1);
  };
  const handleBack = () => {
    setActiveStep((prevActiveStep) => prevActiveStep - 1);
  };
  const handleReset = () => {
    setActiveStep(0);
  };
  const buttonDisabled = activeStep === 1 && answers.some((a) => !a);
  return (
    <Grid container>
      <Grid sm={2} />
      <Grid lg={8} sm={8} spacing={10}>
        <Stepper activeStep={activeStep} alternativeLabel>
          {steps.map((label) => (
            <Step key={label}>
              <StepLabel>{label}</StepLabel>
            </Step>
          ))}
        </Stepper>
        {activeStep === steps.length ? (
          <div>
            <Typography>全ステップの表示を完了</Typography>
            <Button onClick={handleReset}>リセット</Button>
          </div>
        ) : (
          <div>
            <Typography>
              <StepContent stepIndex={activeStep} questionnaireProps={{ answers, setAnswers }} />
            </Typography>
            <Button disabled={activeStep === 0} onClick={handleBack}>
              戻る
            </Button>
            <Button variant="contained" color="primary" onClick={handleNext} disabled={buttonDisabled}>
              {activeStep === steps.length - 1 ? "送信" : "次へ"}
            </Button>
          </div>
        )}
      </Grid>
    </Grid>
  );
}
export default Content;

src / components / Basics.js

import React from "react";
import Radio from "@mui/material/Radio";
import RadioGroup from "@mui/material/RadioGroup";
import FormControlLabel from "@mui/material/FormControlLabel";
import FormControl from "@mui/material/FormControl";
import FormLabel from "@mui/material/FormLabel";
import InputLabel from "@mui/material/InputLabel";
import Select from "@mui/material/Select";
import Questionnaire from "./Questionnaire";

const Basic = () => {
  return (
    <>
      <div style={{ textAlign: "center" }}>
        <p>Basic</p>
        <Questionnaire />
        <FormControl component="fieldset">
          <FormLabel component="legend">- 性別 -</FormLabel>
          <RadioGroup row aria-label="gender" name="row-radio-buttons-group">
            <FormControlLabel value="male" control={<Radio />} label="男性" />
            <FormControlLabel value="female" control={<Radio />} label="女性" />
          </RadioGroup>
        </FormControl>
      </div>
      <div style={{ textAlign: "center" }}>
        <p>Basic</p>
        <Questionnaire />
        <FormLabel component="legend">- 生年月日 -</FormLabel>
        <FormControl sx={{ m: 1, minWidth: 120 }}>
          <InputLabel htmlFor="grouped-native-select">year</InputLabel>
          <Select native defaultValue="" id="grouped-native-select" label="Grouping">
            <option aria-label="None" value="" />
            <optgroup label="year">
              {Array.from(Array(2020), (_, num) => (
                <option key={num} value={num + 1}>
                  {num + 1990}
                </option>
              ))}
            </optgroup>
          </Select>
        </FormControl>
        <FormControl sx={{ m: 1, minWidth: 120 }}>
          <InputLabel htmlFor="grouped-native-select">month</InputLabel>
          <Select native defaultValue="" id="grouped-native-select" label="Grouping">
            <option aria-label="None" value="" />
            <optgroup label="month">
              {Array.from(Array(12), (_, num) => (
                <option key={num} value={num + 1}>
                  {num + 1}
                </option>
              ))}
            </optgroup>
          </Select>
        </FormControl>
        <FormControl sx={{ m: 1, minWidth: 120 }}>
          <InputLabel htmlFor="grouped-native-select">day</InputLabel>
          <Select native defaultValue="" id="grouped-native-select" label="Grouping">
            <option aria-label="None" value="" />
            <optgroup label="day">
              {Array.from(Array(12), (_, num) => (
                <option key={num} value={num + 1}>
                  {num + 1}
                </option>
              ))}
            </optgroup>
          </Select>
        </FormControl>
      </div>
    </>
  );
};
export default Basic;

src / components / Questionnaire.js

import React from "react";
import Typography from "@mui/material/Typography";
import Radio from "@mui/material/Radio";
import RadioGroup from "@mui/material/RadioGroup";
import FormControlLabel from "@mui/material/FormControlLabel";
import FormControl from "@mui/material/FormControl";
import FormLabel from "@mui/material/FormLabel";
import Optional from "./Optional";

export const QUESTIONS = [
  "現在、生命保険に加入されていますか？",
  "現在、入院中ですか。また、3ヶ月以内に医師の診察・検査の結果、入院・手術をすすめられたことがありますか？",
  "過去、5年以内に病気やケガで手術を受けたことまたは継続して７日以上の入院をしたことはありますか？",
];

const Questionnaire = ({ answers, setAnswers }) => {
  const handleAnswer = (answeredIndex, answer) => {
    setAnswers(answers.map((e, i) => (i === answeredIndex ? answer : e)));
  };
  return (
    <div>
      <p>Questionnaire</p>
      <Optional />
      <FormControl component="fieldset">
        {answers
          .filter((_, i) => i === 0 || answers[i - 1])
          .map((answer, i) => (
            <React.Fragment key={i}>
              <FormLabel component="legend">{QUESTIONS[i]}</FormLabel>
              {answer ? (
                <Typography>{answer === "yes" ? "はい" : "いいえ"}</Typography>
              ) : (
                <RadioGroup
                  row
                  aria-label="gender"
                  name="row-radio-buttons-group"
                  onChange={(_evt, value) => {
                    handleAnswer(i, value);
                  }}
                >
                  <FormControlLabel value="yes" control={<Radio />} label="はい" />
                  <FormControlLabel value="no" control={<Radio />} label="いいえ" />
                </RadioGroup>
              )}
            </React.Fragment>
          ))}
      </FormControl>
    </div>
  );
};
export default Questionnaire;

src / components / Optional.js

import React from "react";
import { Grid } from "@mui/material";
import Tooltip from "@mui/material/Tooltip";
import TextField from "@mui/material/TextField";

const Optional = () => {
  return (
    <div>
      <p>Optional</p>

      <Grid container>
        <Grid sm={2} />
        <Grid lg={8} sm={8} spacing={10}>
          <Tooltip title="ご相談内容を記入することができます" placement="top-start" arrow>
            <TextField
              label="ご相談内容"
              fullWidth
              margin="normal"
              rows={4}
              multiline
              variant="outlined"
              placeholder="その他ご要望等あれば、ご記入ください"
            />
          </Tooltip>
        </Grid>
      </Grid>
    </div>
  );
};
export default Optional;

src / components / Confirm.js

import React from "react";
import Basic from "./Basic";

const Confirm = () => {
  return (
    <div style={{ textAlign: "center" }}>
      <Basic />
    </div>
  );
};
export default Confirm;

Answer 1

Basics.jsの<Questionnaire />でanswersをpropsとして渡してないからだと思われます。

Comments

[edu]

k4aさん、回答ありがとうございました！
useContextを使用して、Confirm.js　に基本情報入力及び質問の回答を確認画面に表示するように実装したら、エラーが出たので、useContextを使用せず他の方法を探して実装してみます。