学習[react&NodeJS]#5

日付:21.06.25
参考講義

[React.js]

1.ログインページ

LandingPage.js(開始ページ)

の変更

import React, { useEffect } from 'react';
import axios from 'axios';

function LandingPage() {

    useEffect(() => {
        axios.get('/api/hello')
            .then(response => console.log(response.data))
    }, []);
    return (
        <div style={{
            display: 'flex', justifyContent: 'center', alignItems: 'center',
            width: '100%', height: '100vh'
        }}>
            <h2>시작 페이지</h2>
        </div>
    )
}

export default LandingPage;

先生成

[LoginPage.js]再試行部分->ページ上のフレームワーク

return (
        <div style={{
            display: 'flex', justifyContent: 'center', alignItems: 'center',
            width: '100%', height: '100vh'
        }}>
            <form style={{ display: 'flex', flexDirection: 'column' }}
            >
                <label>Email</label>
                <input type='email' value={} onChange={} />
                <label>Password</label>
                <input type='password' value={} onChange={} />
                <br />
                <button>
                    Login
                </button>
            </form>
        </div>
    )

🔽 結果画面🔽
LoginPage.js]の関数LoginPageState()にステータスを作成

function LoginPage() {
    const [Email, setEmail] = useState("");
    const [Password, setPassword] = useState("");
}

を入力するとonChangeイベントが発生し、ステータスが発生した後に値が変更されます.
-> [LoginPage.js] funtion LoginPagestate()

function LoginPage() {
    const [Email, setEmail] = useState("");
    const [Password, setPassword] = useState("");

    const onEmailHandler = (event) => {
        setEmail(event.currentTarget.value)
    };

    const onPasswordHandler = (event) => {
        setPassword(event.currentTarget.value)
    };
}

onSubmitHandler->ログイン情報入力時のリフレッシュ防止

function LoginPage() {
    const [Email, setEmail] = useState("");
    const [Password, setPassword] = useState("");

    const onEmailHandler = (event) => {
        setEmail(event.currentTarget.value)
    };

    const onPasswordHandler = (event) => {
        setPassword(event.currentTarget.value)
    };
  	const onSubmitHandler = (event) => {
        event.preventDefault(); // 페이지 refresh 방지

        let body = {
            email: Email,
            password: Password,
    };
}

[LoginPage.js]戻り値、onChange、onSubmit修正

...
...
<form style={{ display: 'flex', flexDirection: 'column' }}
                onSubmit={onSubmiHandler}
            >
                <label>Email</label>
                <input type='email' value={Email} onChange={onEmailHandler} />
                <label>Password</label>
                <input type='password' value={Password} onChange={onPasswordHandler} />
                <br />
                <button>
                    Login
                </button>
            </form>
...
...

2.Reduxを使用して情報を伝達する

動作

[LoginPage.js]にdispatchで動作

を作成する.

import { useDispatch } from 'react-redux';

function LoginPage{
  ...
  ...
  const dispatch = useDispatch();
    dispatch(loginUser(body))
                .then(response => {
                    if (response.payload.loginSuccess) {
                        props.history.push('/')
                    } else {
                        alert('Error')
                    }
                });
}

[action]-作成ファイル

[user action.js]

import axios from 'axios';
import {
    LOGIN_USER
} from './types';

export function loginUser(dataToSubmit) {
    const request = axios.post('/api/users/login', dataToSubmit)
        .then(response => response.data)

    return {//reducer로 전송
        type: "LONGIN_USER",
        payload: request,
    }
}

[action]-作成ファイル

[type.js]

export const LOGIN_USER = "login_user";

[Reducers]-[user Reducer.js]作成ファイル

import {
    LOGIN_USER
} from '../_actions/types';

export default function (state = {}, action) {
    switch (action.type) {
        case LOGIN_USER:
            return { ...state, loginSuccess: action.payload }
            break;

        default:
            return state;
    }
}

[reducers]-[index.js]修正

// rootReducer에 Reducer들을 합체
import { combineReducers } from "redux";
import user from './user_reducer';

const rootReducer = combineReducers({
    user,
})

export default rootReducer;

[LoginPage.js]最終コード

import React, { useState } from 'react';
import { useDispatch } from 'react-redux';
import { loginUser } from '../../../_actions/user_action'

function LoginPage(props) {
    const dispatch = useDispatch();
    const [Email, setEmail] = useState("");
    const [Password, setPassword] = useState("");

    const onEmailHandler = (event) => {
        setEmail(event.currentTarget.value)
    };

    const onPasswordHandler = (event) => {
        setPassword(event.currentTarget.value)
    };

    const onSubmitHandler = (event) => {
        event.preventDefault(); // 페이지 refresh 방지

        let body = {
            email: Email,
            password: Password,
        };

        dispatch(loginUser(body))
            .then(response => {
          // 로그인 성공 시 첫 페이지로 이동
                if (response.payload.loginSuccess) {
                    props.history.push('/')
                } else {
                    alert('Error')
                }
            })

    };

    return (
        <div style={{
            display: 'flex', justifyContent: 'center', alignItems: 'center',
            width: '100%', height: '100vh'
        }}>
            <form style={{ display: 'flex', flexDirection: 'column' }}
                onSubmit={onSubmitHandler}
            >
                <label>Email</label>
                <input type='email' value={Email} onChange={onEmailHandler} />
                <label>Password</label>
                <input type='password' value={Password} onChange={onPasswordHandler} />
                <br />
                <button>
                    Login
                </button>
            </form>
        </div>
    )
}

export default LoginPage

検査結果は

Full Code

Walang Github

Walang Notion