如何使用带上传功能的短划线按钮

Question

是否有人知道我是否正确设置了此按钮（用于Dash），以便能够读取下拉列表和上载功能的输入？我的app.callback（）呢？ 我需要一些帮助来分析为什么当我点击submit而什么也没发生时它不能正常工作

#Uploading file definitions
def save_file(name, content):
    """Decode and store a file uploaded with Plotly Dash."""
    data = content.encode("utf8").split(b";base64,")[1]
    with open(os.path.join(UPLOAD_DIRECTORY, name), "wb") as fp:
        fp.write(base64.decodebytes(data))
def uploaded_files():
    """List the files in the upload directory."""
    files = []
    for filename in os.listdir(UPLOAD_DIRECTORY):
        path = os.path.join(UPLOAD_DIRECTORY, filename)
        if os.path.isfile(path):
            files.append(filename)
    return files
def file_download_link(filename):
    """Create a Plotly Dash 'A' element that downloads a file from the app."""
    location = "/download/{}".format(urlquote(filename))
    return html.A(filename, href=location)
    
@app.callback(
Output("file-list", "children"),
[Input("upload-data", "filename"), Input("upload-data", "contents")],)

def update_output(uploaded_filenames, uploaded_file_contents):
    """Save uploaded files and regenerate the file list."""

    if uploaded_filenames is not None and uploaded_file_contents is not None:
        for name, data in zip(uploaded_filenames, uploaded_file_contents):
            save_file(name, data)

    files = uploaded_files()
    if len(files) == 0:
        return [html.Li("No files yet!")]
    else:
        return [html.Li(file_download_link(filename)) for filename in files]

#Callback for dropdown menu
@app.callback(dash.dependencies.Output('dd-output-container', 'children'),[dash.dependencies.Input('Categories', 'value')])
def update_output_dropdown(value):
    return 'You have selected "{}"'.format(value)


#Callback for submitting everything.
@app.callback(Output('target', 'children'), Input('submit', 'n_clicks'))
def callback(n_clicks):
    if (n_clicks != 0):
        
        #Read the uploaded file and calculate the category from dropdown
        for file in uploaded_files():
            with open(file) as f:
                dfs = pd.read_excel(file)
                xl = pd.ExcelFile(dfs)
                if xl.parse(sheet_name= 'Spikes'): 

这是一个视觉： Visual