Flask is an extremely popular micro-framework for developing web applications in Python, praised for its simplicity, flexibility, and ease of use. A common feature that developers need to implement in web applications is the ability to allow users to download files. This can be accomplished in various ways, but here we will focus on how to force download a file using Flask.
Start by creating a new Python file (for example, app.py) and set up your basic Flask application:
from flask import Flask, send_file
app = Flask(__name__)
@app.route('/')
def home():
return 'Welcome to the file download page!'
if __name__ == '__main__':
app.run(debug=True)
To force a file to be downloaded, you'll use Flask's send_file() function, which allows you to send files to the client. You can specify various parameters such as file path, MIME type, and most importantly, you can set the Content-Disposition header to attachment to force the browser to show the window download dialog instead of viewing the file.
@app.route('/download')
def download_file():
file_path = 'path/to/your/file.ext'
return send_file(file_path, as_attachment=True)
If you want to customize the name of the file the user will see when downloading, you can do so by passing a header dictionary with a custom Content-Disposition key to send_file():
from flask import safe_join
@app.route('/download-custom')
def download_file_custom_name():
file_path = safe_join('path/to/your', 'file.ext')
file_name = 'custom_name.ext'
return send_file(file_path, as_attachment=True, download_name=file_name)
Conclusion
Forcing file downloads in a Flask application is a simple and straightforward process. By using the send_file() function and configuring the headers correctly, you can easily allow users to download files from your website. Remember to always test download features to ensure they work as expected across different browsers and devices.