forms in React: Radio button, select&option, submit the form

흠..리액트에서는 forms 만드는게 뭔가 정말 어려운 느낌이다.
방금은 Radio button에 관한 강의를 들었는데
아래 코드를 살펴보자

import React from "react"

export default function Form() {
    const [formData, setFormData] = React.useState(
        {
            firstName: "", 
            lastName: "", 
            email: "", 
            comments: "", 
            isFriendly: true,
            employment: ""
        }
    )
    console.log(formData.employment)
    
    function handleChange(event) {
        const {name, value, type, checked} = event.target
        setFormData(prevFormData => {
            return {
                ...prevFormData,
                [name]: type === "checkbox" ? checked : value
            }
        })
    }
    
    return (
        <form>
            <input
                type="text"
                placeholder="First Name"
                onChange={handleChange}
                name="firstName"
                value={formData.firstName}
            />
            <input
                type="text"
                placeholder="Last Name"
                onChange={handleChange}
                name="lastName"
                value={formData.lastName}
            />
            <input
                type="email"
                placeholder="Email"
                onChange={handleChange}
                name="email"
                value={formData.email}
            />
            <textarea 
                value={formData.comments}
                placeholder="Comments"
                onChange={handleChange}
                name="comments"
            />
            <input 
                type="checkbox" 
                id="isFriendly" 
                checked={formData.isFriendly}
                onChange={handleChange}
                name="isFriendly"
            />
            <label htmlFor="isFriendly">Are you friendly?</label>
            <br />
            <br />
            
            <fieldset>
                <legend>Current employment status</legend>
                
                <input 
                    type="radio"
                    id="unemployed"
                    name="employment"
                    value="unemployed"
                    checked={formData.employment === "unemployed"}
                    onChange={handleChange}
                />
                <label htmlFor="unemployed">Unemployed</label>
                <br />
                
                <input 
                    type="radio"
                    id="part-time"
                    name="employment"
                    value="part-time"
                    checked={formData.employment === "part-time"}
                    onChange={handleChange}
                />
                <label htmlFor="part-time">Part-time</label>
                <br />
                
                <input 
                    type="radio"
                    id="full-time"
                    name="employment"
                    value="full-time"
                    checked={formData.employment === "full-time"}
                    onChange={handleChange}
                />
                <label htmlFor="full-time">Full-time</label>
                <br />
                
            </fieldset>
        </form>
    )
}

이 코드를 보면 라디오버튼은 input을 쓰고 그다음 type에 radio라고 적는걸 볼 수 있다.

 <input 
                    type="radio"
                    id="unemployed"
                    name="employment"
                    value="unemployed"
                    checked={formData.employment === "unemployed"}
                    onChange={handleChange}
                />

그리고 각각 문항에 따라 id를 적어주었고
무엇보다 여기서 다른 애들과 다른 점은

checked={formData.employment === "unemployed"}

checked부분을 이렇게 써주는거였다.
그리고 이건 checkbox와는 다르게 value도 써줬음!

다음으로 select&option을 알아보자..
일단 밑의 코드 보기

import React from "react"

export default function Form() {
    const [formData, setFormData] = React.useState(
        {
            firstName: "", 
            lastName: "", 
            email: "", 
            comments: "", 
            isFriendly: true,
            employment: "",
            favColor: ""
        }
    )
    console.log(formData.favColor)
    
    function handleChange(event) {
        console.log(event)
        const {name, value, type, checked} = event.target
        setFormData(prevFormData => {
            return {
                ...prevFormData,
                [name]: type === "checkbox" ? checked : value
            }
        })
    }
    
    return (
        <form>
            <input
                type="text"
                placeholder="First Name"
                onChange={handleChange}
                name="firstName"
                value={formData.firstName}
            />
            <input
                type="text"
                placeholder="Last Name"
                onChange={handleChange}
                name="lastName"
                value={formData.lastName}
            />
            <input
                type="email"
                placeholder="Email"
                onChange={handleChange}
                name="email"
                value={formData.email}
            />
            <textarea 
                value={formData.comments}
                placeholder="Comments"
                onChange={handleChange}
                name="comments"
            />
            <input 
                type="checkbox" 
                id="isFriendly" 
                checked={formData.isFriendly}
                onChange={handleChange}
                name="isFriendly"
            />
            <label htmlFor="isFriendly">Are you friendly?</label>
            <br />
            <br />
            
            <fieldset>
                <legend>Current employment status</legend>
                <input 
                    type="radio"
                    id="unemployed"
                    name="employment"
                    value="unemployed"
                    checked={formData.employment === "unemployed"}
                    onChange={handleChange}
                />
                <label htmlFor="unemployed">Unemployed</label>
                <br />
                
                <input 
                    type="radio"
                    id="part-time"
                    name="employment"
                    value="part-time"
                    checked={formData.employment === "part-time"}
                    onChange={handleChange}
                />
                <label htmlFor="part-time">Part-time</label>
                <br />
                
                <input 
                    type="radio"
                    id="full-time"
                    name="employment"
                    value="full-time"
                    checked={formData.employment === "full-time"}
                    onChange={handleChange}
                />
                <label htmlFor="full-time">Full-time</label>
                <br />
            </fieldset>
            <br />
            
            <label htmlFor="favColor">What is your favorite color?</label>
            <br />
            <select 
                id="favColor"
                value={formData.favColor}
                onChange={handleChange}
                name="favColor"
            >
                <option value="">-- Choose --</option>
                <option value="red">Red</option>
                <option value="orange">Orange</option>
                <option value="yellow">Yellow</option>
                <option value="green">Green</option>
                <option value="blue">Blue</option>
                <option value="indigo">Indigo</option>
                <option value="violet">Violet</option>
            </select>
        </form>
    )
}

일단 select애들을 저렇게 value를 적어주고
다른 애들과 마찬가지로 id, value, onChange,name을 적어준다
그리고 아래 이부분에도

 const [formData, setFormData] = React.useState(
        {
            firstName: "", 
            lastName: "", 
            email: "", 
            comments: "", 
            isFriendly: true,
            employment: "",
            favColor: ""
        }
    )

favColor를 empty string으로 추가해줬음 ><!

다음으로 submit 하는걸 어떻게 리액트에서 할 수 있는지 살펴보자

import React from "react"

export default function Form() {
    const [formData, setFormData] = React.useState(
        {
            firstName: "", 
            lastName: "", 
            email: "", 
            comments: "", 
            isFriendly: true,
            employment: "",
            favColor: ""
        }
    )
    
    function handleChange(event) {
        const {name, value, type, checked} = event.target
        setFormData(prevFormData => {
            return {
                ...prevFormData,
                [name]: type === "checkbox" ? checked : value
            }
        })
    }
    
    function handleSubmit(event) {
        event.preventDefault()
        // submitToApi(formData)
        console.log(formData)
    }
    
    return (
        <form onSubmit={handleSubmit}>
            <input
                type="text"
                placeholder="First Name"
                onChange={handleChange}
                name="firstName"
                value={formData.firstName}
            />
            <input
                type="text"
                placeholder="Last Name"
                onChange={handleChange}
                name="lastName"
                value={formData.lastName}
            />
            <input
                type="email"
                placeholder="Email"
                onChange={handleChange}
                name="email"
                value={formData.email}
            />
            <textarea 
                value={formData.comments}
                placeholder="Comments"
                onChange={handleChange}
                name="comments"
            />
            <input 
                type="checkbox" 
                id="isFriendly" 
                checked={formData.isFriendly}
                onChange={handleChange}
                name="isFriendly"
            />
            <label htmlFor="isFriendly">Are you friendly?</label>
            <br />
            <br />
            
            <fieldset>
                <legend>Current employment status</legend>
                <input 
                    type="radio"
                    id="unemployed"
                    name="employment"
                    value="unemployed"
                    checked={formData.employment === "unemployed"}
                    onChange={handleChange}
                />
                <label htmlFor="unemployed">Unemployed</label>
                <br />
                
                <input 
                    type="radio"
                    id="part-time"
                    name="employment"
                    value="part-time"
                    checked={formData.employment === "part-time"}
                    onChange={handleChange}
                />
                <label htmlFor="part-time">Part-time</label>
                <br />
                
                <input 
                    type="radio"
                    id="full-time"
                    name="employment"
                    value="full-time"
                    checked={formData.employment === "full-time"}
                    onChange={handleChange}
                />
                <label htmlFor="full-time">Full-time</label>
                <br />
            </fieldset>
            <br />
            
            <label htmlFor="favColor">What is your favorite color?</label>
            <br />
            <select 
                id="favColor" 
                value={formData.favColor}
                onChange={handleChange}
                name="favColor"
            >
                <option value="red">Red</option>
                <option value="orange">Orange</option>
                <option value="yellow">Yellow</option>
                <option value="green">Green</option>
                <option value="blue">Blue</option>
                <option value="indigo">Indigo</option>
                <option value="violet">Violet</option>
            </select>
            <br />
            <br />
            <button>Submit</button>
        </form>
    )
}

button이 form안에 있으면 default로 submit type이기 때문에
그냥

<button>Submit</button>

이렇게 써주고

함수 이렇게 작성해준 뒤

  function handleSubmit(event) {
        event.preventDefault()
        // submitToApi(formData)
        console.log(formData)
    }

여기에서 event.preventDefault() 이렇게 작성해준 이유는
페이지가 submit한뒤에 새로고침 되지 않게 해주기 위해서다
저거 안적어주면 페이지가 submit누른다음에 새로고침됨 ㅠㅠ

그리고 form 부분에 이렇게 함수부르는걸 작성해줌

  <form onSubmit={handleSubmit}>
            <input
                type="text"
                placeholder="First Name"
                onChange={handleChange}
                name="firstName"
                value={formData.firstName}
            />