Flask – File Uploading Handling file upload in Flask is very easy. It needs an HTML form with its enctype attribute set to ‘multipart/form-data’, posting the file to a URL. The URL handler fetches file from request.files[] object and saves it to the desired location. Each uploaded file is first saved in a temporary location on the server, before it is actually saved to its ultimate location. Name of destination file can be hard-coded or can be obtained from filename property of request.files[file] object. However, it is recommended to obtain a secure version of it using the secure_filename() function. It is possible to define the path of default upload folder and maximum size of uploaded file in configuration settings of Flask object. app.config[‘UPLOAD_FOLDER’] Defines path for upload folder app.config[‘MAX_CONTENT_PATH’] Specifies maximum size of file yo be uploaded – in bytes The following code has ‘/upload’ URL rule that displays ‘upload.html’ from the templates folder, and ‘/upload-file’ URL rule that calls uploader() function handling upload process. ‘upload.html’ has a file chooser button and a submit button. You will see the screen as shown below. Click Submit after choosing file. Form’s post method invokes ‘/upload_file’ URL. The underlying function uploader() does the save operation. Following is the Python code of Flask application. from flask import Flask, render_template, request from werkzeug import secure_filename app = Flask(__name__) @app.route('/upload') def upload_file(): return render_template('upload.html') @app.route('/uploader', methods = ['GET', 'POST']) def upload_file(): if request.method == 'POST': f = request.files['file'] f.save(secure_filename(f.filename)) return 'file uploaded successfully' if __name__ == '__main__': app.run(debug = True)