Return a dictionary with content and filename keys for raw text. Key Features and Best Practices
: For Excel files, use dcc.send_data_frame(df.to_excel, "filename.xlsx") . Ensure you have an engine like openpyxl or xlsxwriter installed in your environment.
Dash provides specialized helper functions to format data for the dcc.Download component: Helper Function Description Pandas DataFrames Sends a DataFrame as a CSV or Excel file. dcc.send_file Existing Files python dash dcc download
: For very large files (e.g., >100MB), consider using a dedicated Flask route with flask.send_from_directory instead of the Dash component to avoid memory bottlenecks within the Dash callback. Download | Dash for Python Documentation | Plotly
: Always use prevent_initial_call=True in your download callback. Without this, the browser may attempt to trigger a download as soon as the page loads. Return a dictionary with content and filename keys
: The dcc.Download component does not render any visual elements; it simply manages the browser's download stream.
Downloads a file already saved on the server's disk (e.g., a PDF or image). Raw Binary Useful for dynamically generated images or zip files. dict(content=...) Text Strings Dash provides specialized helper functions to format data
To use dcc.Download , you typically pair it with a trigger, such as an html.Button .