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[source] | |
|---|---|
st.download_button(label, data, file_name=None, mime=None, key=None, help=None, on_click=None, args=None, kwargs=None, *, type="secondary", disabled=False, use_container_width=False) | |
| Parameters | |
label (str) | A short label explaining to the user what this button is for. The label can optionally contain Markdown and supports the following elements: Bold, Italics, Strikethroughs, Inline Code, and Emojis. This also supports:
Unsupported elements are unwrapped so only their children (text contents) render. Display unsupported elements as literal characters by backslash-escaping them. E.g. 1\. Not an ordered list. |
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. |
type ("secondary" or "primary") | An optional string that specifies the button type. Can be "primary" for a button with additional emphasis or "secondary" for a normal button. Defaults to "secondary". |
disabled (bool) | An optional boolean, which disables the download button if set to True. The default is False. |
use_container_width (bool) | An optional boolean, which makes the button stretch its width to match the parent container. |
| Returns | |
(bool) | True if the button was clicked on the last run of the app, False otherwise. |
Examples
Download a large DataFrame as a CSV:
import streamlit as st @st.cache def convert_df(df): # IMPORTANT: Cache the conversion to prevent computation on every rerun return df.to_csv().encode('utf-8') csv = convert_df(my_large_df) st.download_button( label="Download data as CSV", data=csv, file_name='large_df.csv', mime='text/csv', )Download a string as a file:
import streamlit as st text_contents = '''This is some text''' st.download_button('Download some text', text_contents)Download a binary file:
import streamlit as st binary_contents = b'example content' # Defaults to 'application/octet-stream' st.download_button('Download binary file', binary_contents)Download an image:
import streamlit as st with open("flower.png", "rb") as file: btn = st.download_button( label="Download image", data=file, file_name="flower.png", mime="image/png" )
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