Saving uploaded files in Flask - Mini Project: Build & Apply

Saving uploaded files

📖 Scenario: You are building a simple web app where users can upload a file. You want to save the uploaded file on the server so you can use it later.

🎯 Goal: Create a Flask app that accepts a file upload from a user and saves the file to a folder on the server.

📋 What You'll Learn

Create a Flask app with a route to upload files

Set a folder path to save uploaded files

Use Flask's request object to get the uploaded file

Save the uploaded file to the specified folder

💡 Why This Matters

🌍 Real World

Uploading and saving files is common in web apps for user profile pictures, documents, or media content.

💼 Career

Understanding file uploads is essential for backend web developers working with Flask or similar frameworks.

1

Set up Flask app and upload folder

Import Flask and request from flask. Create a Flask app called app. Set a variable UPLOAD_FOLDER to the string 'uploads/'.

Flask

from flask import Flask, request

# Your code here

Need a hint?

Use Flask(__name__) to create the app. Set UPLOAD_FOLDER as a string with the folder name.

2

Create upload route and HTML form

Add a route /upload to the app that accepts GET and POST methods. Inside the route function upload_file, if the request method is GET, return a simple HTML form string with a file input named file and a submit button.

Flask

from flask import Flask, request

app = Flask(__name__)
UPLOAD_FOLDER = 'uploads/'

@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
    # Your code here

Need a hint?

Use @app.route with methods=['GET', 'POST']. Return a form with enctype='multipart/form-data' and a file input named file.

3

Get uploaded file from request

Inside the upload_file function, after the GET block, add code for POST method. Get the uploaded file from request.files using the key 'file' and store it in a variable called uploaded_file.

Flask

from flask import Flask, request

app = Flask(__name__)
UPLOAD_FOLDER = 'uploads/'

@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
    if request.method == 'GET':
        return '''
            
                
                
            
        '''
    uploaded_file = request.files['file']  # Your code here

Need a hint?

Use request.files['file'] to get the uploaded file object.

4

Save the uploaded file

Still inside the upload_file function, after getting uploaded_file, save it to the folder UPLOAD_FOLDER using the save() method. Use uploaded_file.filename to get the original filename. Return a string 'File saved successfully' after saving.

Flask

from flask import Flask, request

app = Flask(__name__)
UPLOAD_FOLDER = 'uploads/'

@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
    if request.method == 'GET':
        return '''
            
                
                
            
        '''
    uploaded_file = request.files['file']
    # Save the file here
    # Your code here

Need a hint?

Use uploaded_file.save() with the path combining UPLOAD_FOLDER and uploaded_file.filename. Return a success message string.