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.
If you want to prevent your app from rerunning when a user clicks the download button, wrap the download button in a fragment.
| 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 GitHub-flavored Markdown of the following types: Bold, Italics, Strikethroughs, Inline Code, and Links. Unsupported Markdown 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". See the body parameter of st.markdown for additional, supported Markdown directives. |
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) | Whether to expand the button's width to fill its parent container. If use_container_width is False (default), Streamlit sizes the button to fit its contents. If use_container_width is True, the width of the button matches its parent container. In both cases, if the contents of the button are wider than the parent container, the contents will line wrap. |
| 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_data 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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