Display a download button widget.

This is useful when you would like to provide a way for your users to download a file directly from your app.

Note that the data to be downloaded is stored in-memory while the user is connected, so it's a good idea to keep file sizes under a couple hundred megabytes to conserve memory.

Function signature

st.download_button(label, data, file_name=None, mime=None, key=None, help=None, on_click=None, args=None, kwargs=None)

Parameters

label (str)

A short label explaining to the user what this button is for.

data (str or bytes or file)

The contents of the file to be downloaded. See example below for caching techniques to avoid recomputing this data unnecessarily.

file_name (str)

An optional string to use as the name of the file to be downloaded, such as 'my_file.csv'. If not specified, the name will be automatically generated.

mime (str or None)

The MIME type of the data. If None, defaults to "text/plain" (if data is of type str or is a textual file) or "application/octet-stream" (if data is of type bytes or is a binary file).

key (str or int)

An optional string or integer to use as the unique key for the widget. If this is omitted, a key will be generated for the widget based on its content. Multiple widgets of the same type may not share the same key.

help (str)

An optional tooltip that gets displayed when the button is hovered over.

on_click (callable)

An optional callback invoked when this button is clicked.

args (tuple)

An optional tuple of args to pass to the callback.

kwargs (dict)

An optional dict of kwargs to pass to the callback.

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