フロントでログイン機能を実装する。(Step2:Rest通信し、値を取得する。)

[前回記事](https://qiita.com/kouji0705/items/f8c8952b36737bbce78b)の続きです。
前回までにログインAPIを作成しました。今回はフロント側でAPIをコールし、フロントで値を出力するまでをゴールとします。

### 成果物
![スクリーンショット 2022-08-11 13.56.24.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/599049/4a28fd31-0399-b762-79f0-677974a5b893.png)

LOGINボタン押下時に、Rest通信し値を取得する。作成したAPIではオウム返しのため、リクエスト内容がそのまま表示されます。

### Hands-on

```shell:ディレクトリ構成
~/develop/react/react_study/login$ tree -I node_modules 
.
├── README.md
├── package.json
├── public
│   ├── favicon.ico
│   ├── index.html
│   ├── logo192.png
│   ├── logo512.png
│   ├── manifest.json
│   └── robots.txt
├── src
│   ├── App.tsx
│   ├── components
│   │   ├── Header.tsx
│   │   └── Login.tsx
│   ├── index.tsx
│   └── types
│       └── User.ts
├── tsconfig.json
└── yarn.lock

4 directories, 15 files
```

```json:package.josn
{
  "name": "login",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@emotion/react": "^11.10.0",
    "@emotion/styled": "^11.10.0",
    "@mui/icons-material": "^5.8.4",
    "@mui/material": "^5.10.0",
    "@testing-library/jest-dom": "^5.14.1",
    "@testing-library/react": "^13.0.0",
    "@testing-library/user-event": "^13.2.1",
    "@types/jest": "^27.0.1",
    "@types/node": "^16.7.13",
    "@types/react": "^18.0.0",
    "@types/react-dom": "^18.0.0",
    "axios": "^0.27.2",
    "react": "^18.2.0",
    "react-dom": "^18.2.0",
    "react-scripts": "5.0.1",
    "typescript": "^4.4.2",
    "web-vitals": "^2.1.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}
```

```tsx:index.tsx
import React from "react";
import ReactDOM from "react-dom/client";
import App from "./App";

const root = ReactDOM.createRoot(
  document.getElementById("root") as HTMLElement
);
root.render(
  <React.StrictMode>
    <App />
  </React.StrictMode>
);

```

```tsx:App.tsx
import CssBaseline from "@mui/material/CssBaseline";
import { ThemeProvider, createTheme } from "@mui/material/styles";
import Header from "./components/Header";
import { Login } from "./components/Login";

function App() {
  const theme = createTheme({
    palette: {
      mode: "light",
    },
  });

  return (
    <ThemeProvider theme={theme}>
      <CssBaseline />
      <Header />
      <Login />
    </ThemeProvider>
  );
}

export default App;
```


```tsx:Header.tsx
import AppBar from "@mui/material/AppBar";
import Box from "@mui/material/Box";
import Toolbar from "@mui/material/Toolbar";
import Typography from "@mui/material/Typography";

export default function Header() {
  return (
    <Box sx={{ flexGrow: 1 }}>
      <AppBar position="static">
        <Toolbar>
          <Typography variant="h6" component="div" sx={{ flexGrow: 1 }}>
            ヘッダー
          </Typography>
        </Toolbar>
      </AppBar>
    </Box>
  );
}
```

```tsx:Login.tsx
import {
  Box,
  Button,
  Card,
  CardActions,
  CardContent,
  CardHeader,
  TextField,
} from "@mui/material";
import axios from "axios";
import { memo, useState } from "react";
import { User } from "../types/User";

export const Login = memo(() => {
  const [userId, setUserId] = useState("");
  const [password, setPassword] = useState("");

  const cardStyle = {
    display: "block",
    transitionDuration: "0.3s",
    height: "450px",
    width: "400px",
    variant: "outlined",
  };

  const onClickLogin = async () => {
    const test = await axios.post<User>("http://localhost:1323/api/login", {
      user_id: userId,
      password,
    });
    console.log(test.data);
  };

  return (
    <Box
      display="flex"
      alignItems="center"
      justifyContent="center"
      padding={20}
    >
      <Card style={cardStyle}>
        <CardHeader title="ログインページ" />
        <CardContent>
          <div>
            <TextField
              fullWidth
              id="username"
              type="email"
              label="Username"
              placeholder="Username"
              margin="normal"
              onChange={(e) => setUserId(e.target.value)}
            />
            <TextField
              fullWidth
              id="password"
              type="password"
              label="Password"
              placeholder="Password"
              margin="normal"
              onChange={(e) => setPassword(e.target.value)}
            />
          </div>
        </CardContent>
        <CardActions>
          <Button
            variant="contained"
            size="large"
            color="secondary"
            onClick={onClickLogin}
          >
            Login
          </Button>
        </CardActions>
      </Card>
    </Box>
  );
});
```