当进入后端控制器时，Reactjs的FormData变成了空的。

我正在创建一个图书库管理CRUD，我正在使用React@18。我正在努力向我的mongdb地图集添加数据，因为每当我通过redux向axios.post传递formData时，我总是在后端控制器上得到空req.body，然而当我使用postman通过form-data向我的数据库添加数据时，这并没有发生。

这是我的bookCreate.js

const BookCreate = () => {
    const [title, setTitle] = useState('')
    const [responsibility, setResponsibility] = useState('')
    const [uniform_title, setUniform_title] = useState('')
    const [parallel_title, setParallel_title] = useState('')
    const [main_author, setMain_author] = useState('')
    const [other_author, setOther_author] = useState('')
    const [contributors, setContributors] = useState('')
    const [corp_author, setCorp_author] = useState('')
    const [placePub, setPlacePub] = useState('')
    const [publisher, setPublisher] = useState('')
    const [yearPub, setYearPub] = useState('')
    ...
    const submitHandler = (e) => {
        e.preventDefault();
        const formData = new FormData();
        formData.set('title', title);
        formData.set('responsibility', responsibility);
        formData.set('uniform_title', uniform_title);
        formData.set('parallel_title', parallel_title);
        formData.set('main_author', main_author);
        formData.set('other_author', other_author);
        formData.set('contributors', contributors);
        formData.set('corp_author', corp_author);
        formData.set('placePub', placePub);
        formData.set('publisher', publisher);
        formData.set('yearPub', yearPub);
       dispatch(newBooks(formData))
    }
    return (
    
     <Fragment>
            <MetaData title={'TUP-T Online Library - Admin'} />
            {/*<div className="row">*/}
                    <SideNavbarAdmin/>
                    <div></div>
                <div className="dashboard-content">
                    <div className="dashboard-page">
                        <div className="dashboard-header">
                            <h1>Add Book</h1>
                        </div> 
                        <div className="dashboard-body">
                            <form className="" onSubmit={submitHandler} encType='multipart/form-data'>
                                <div className="row g-3">
                                    <div className="col md-6">
                                        <div className="form-group">
                                            <label htmlFor="title_field">Title</label>
                                            <input
                                                type="text"
                                                id="title_field"
                                                className="form-control"
                                                name='title'
                                                value={title}
                                                onChange={(e) => setTitle(e.target.value)}
                                            />
                                        </div>
                                        ...
}

bookAction.js

export const newBooks = (bookData) => async (dispatch) => {
    try {

        dispatch({ type: NEW_BOOK_REQUEST })

        const config = {
            headers: {
                 "Content-Type": "multipart/form-data"
                 // "Content-Type": "application/json"
            }
        }
        // for(var pair of bookData.entries()) {
        //    console.log(pair[0]+ ', '+ pair[1]); 
        // }

        const { data } = await axios.post('/api/v1/book/new', bookData, config)

        dispatch({
            type: NEW_BOOK_SUCCESS,
            payload: data
        })

    } catch (error) {
        dispatch({
            type: NEW_BOOK_FAIL,
            payload: error.response.data.message
        })
    }
}

bookController.js

exports.createBook = async (req, res, next) => {
    console.log(req.body);
    }