How to get columns of uploaded excel file?

Panel
1

On Discord (link) jase64 asks how to get the columns of an uploaded excel file.

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2

You are almost there. The error you mention

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Is because you are taking columns on the function fn_uploaded. Instead you should run the function fn_uploaded() as this will return the dataframe. Then you can take get the columns fn_uploaded().columns.

In Panel you would often pn.bind, @pn.depends or use pn.rx on the function fn_uploaded. For example like below.

import pandas as pd
import panel as pn
import io

pn.extension("tabulator")

file_input = pn.widgets.FileInput()

def get_data(file):
    if file is not None:
        df = pd.read_excel(io.BytesIO(file), engine='openpyxl')
        return df
    return pd.DataFrame()

upload = pn.widgets.FileInput(accept='.xlsx', multiple=False)

fn_uploaded = pn.bind(get_data, file=upload.param.value)

def get_columns(df):
    return f"Columns: {df.columns.tolist()}"
columns = pn.bind(get_columns, df=fn_uploaded)

pn.Column(
    upload,
    pn.pane.Str(fn_uploaded, height=75),
    columns,
).servable()