this is loginform
=============================
import React, { Component } from 'react'
import { Redirect } from 'react-router-dom'
import googleButton from './google_signin_buttons/web/1x/btn_google_signin_dark_normal_web.png'

class LoginForm extends Component {
    constructor() {
        super()
        this.state = {
            username: "",
            password: "",
            redirectTo: null
        }

        this.handleSubmit = this.handleSubmit.bind(this)
        this.handleChange = this.handleChange.bind(this)

    }

    handleChange(event) {
        this.setState({
            [event.target.name]: event.target.value
        })
    }

    handleSubmit(event) {
        event.preventDefault()
        console.log('handleSubmit')
        this.props._login(this.state.username, this.state.password)
        this.setState({
            redirectTo: '/'
        })
    }

    render() {
        if (this.state.redirectTo) {
            return <Redirect to={{ pathname: this.state.redirectTo }} />
        }

        else
        {
            return (
                <div className="LoginForm">
                    <h1>Login Form </h1>
                    <form>
                        <label htmlFor="username">Username: </label>
                        <input
                            type="text"
                            name="username"
                            value={this.state.username}
                            onChange={this.handleChange}
                        />
                        <label htmlFor="password">Password: </label>
                        <input
                            type="password"
                            name="password"
                            value={this.state.password}
                            onChange={this.handleChange}
                        />
                        <button onClick={this.handleSubmit}>Login</button>
                    </form>
                    <a href="http://localhost:4200/auth/google">
                        <img src={googleButton} alt="sign into google account" />
                    </a>
                </div>
                )
        }
    }
}

export default LoginForm



=============================================


this is app.js
===============
_login(username, password) {
        axios.post('http://localhost:4200/auth/login', {
            username,
            password
        })
            .then(response => {
                console.log(response)
                if (response.status === 200) {
                    this.setState({
                        loggedIn: true,
                        user:response.data.user
                    })
                }
            })
    }

  render() {
    return (
        <div className="App">
            <div className="Appheader">
                <Header user={this.state.user} />
                <DisplayLinks _logout={this._logout} loggedIn={this.state.loggedIn} />
                <Route exact path="/" render={() => <Home user={this.state.user} />} />
                <Route exact path="/login" render={() => <LoginForm
                    _login={this._login}
                    _googleSignin={this._googleSignin}
                />}
                />
                <Route exact path="/signup" component={SignupForm} />
                {/*<Route path='/add-item' component={AddItem} />
                <Route path='/edit/:id' component={EditItem} />*/}
            </div>

            <div>
                <h2>Welcome to React</h2>
                <Link to={"/add-item"} className="btn btn-primary">Add New</Link>

                <IndexItem />
            </div>


            {/*<div>
            {this.props.children}
          </div>*/}

        </div>