**Course Title:** Mastering Flask Framework: Building Modern Web Applications **Section Title:** File Uploads and Cloud Storage Integration **Topic:** Implement a file upload feature that stores files in cloud storage (e.g., AWS S3).(Lab topic) **Objective:** By the end of this topic, you will be able to implement a file upload feature in your Flask application that stores files in cloud storage using AWS S3. You will learn how to handle file uploads, validate and process uploaded files, and integrate with AWS S3 to store files securely. **Prerequisites:** * Basic understanding of Flask and its ecosystem * Familiarity with AWS S3 and its API * Knowledge of Python and its libraries (e.g., boto3, flask) **Step 1: Install Required Libraries** To implement file uploads and store files in AWS S3, you will need to install the following libraries: * `boto3` for interacting with AWS S3 * `flask` for building the Flask application * `flask_wtf` for handling file uploads You can install these libraries using pip: ```bash pip install boto3 flask flask_wtf ``` **Step 2: Set up AWS S3** To use AWS S3, you will need to create an AWS account and set up an S3 bucket. You can follow the instructions on the AWS website to create an S3 bucket and obtain your access keys. **Step 3: Configure Flask Application** In your Flask application, you will need to configure the `boto3` library to interact with AWS S3. You can do this by creating a `config.py` file and adding the following code: ```python import os AWS_ACCESS_KEY_ID = os.environ.get('AWS_ACCESS_KEY_ID') AWS_SECRET_ACCESS_KEY = os.environ.get('AWS_SECRET_ACCESS_KEY') AWS_S3_BUCKET_NAME = os.environ.get('AWS_S3_BUCKET_NAME') ``` You will also need to install the `boto3` library and import it in your Flask application: ```python import boto3 ``` **Step 4: Handle File Uploads** To handle file uploads, you will need to create a form in your Flask application that allows users to select a file to upload. You can use the `flask_wtf` library to create a form that handles file uploads. Here is an example of how you can create a form that handles file uploads: ```python from flask_wtf import FlaskForm from wtforms import FileField class FileUploadForm(FlaskForm): file = FileField('File') ``` **Step 5: Validate and Process Uploaded Files** To validate and process uploaded files, you will need to create a function that checks the file type and size, and then uploads the file to AWS S3. Here is an example of how you can create a function that validates and processes uploaded files: ```python from flask import request from boto3 import client def upload_file(file): s3 = client('s3', aws_access_key_id=AWS_ACCESS_KEY_ID, aws_secret_access_key=AWS_SECRET_ACCESS_KEY) file_name = file.filename file_type = file.mimetype file_size = file.content_length if file_type not in ['image/jpeg', 'image/png', 'application/pdf']: return 'Invalid file type' if file_size > 1024 * 1024 * 10: return 'File too large' s3.upload_fileobj(file, AWS_S3_BUCKET_NAME, file_name) return 'File uploaded successfully' ``` **Step 6: Integrate with AWS S3** To integrate with AWS S3, you will need to create a function that uploads the file to AWS S3. Here is an example of how you can create a function that integrates with AWS S3: ```python from flask import request from boto3 import client def upload_file_to_s3(file): s3 = client('s3', aws_access_key_id=AWS_ACCESS_KEY_ID, aws_secret_access_key=AWS_SECRET_ACCESS_KEY) file_name = file.filename file_type = file.mimetype file_size = file.content_length if file_type not in ['image/jpeg', 'image', 'application/pdf']: return 'Invalid file type' if file_size > 1024 * 1024 * 10: return 'File too large' s3.upload_fileobj(file, AWS_S3_BUCKET_NAME, file_name) return 'File uploaded successfully' ``` **Conclusion:** In this topic, you learned how to implement a file upload feature in your Flask application that stores files in cloud storage using AWS S3. You learned how to handle file uploads, validate and process uploaded files, and integrate with AWS S3 to store files securely. **Exercise:** Implement a file upload feature in your Flask application that stores files in cloud storage using AWS S3. **Note:** This is a lab topic, and you are expected to implement the code yourself. If you have any questions or need help, please ask in the comments below. **External Resources:** * AWS S3 Documentation: <https://docs.aws.amazon.com/AmazonS3/latest/dev/Welcome.html> * Flask Documentation: <https://flask.palletsprojects.com/en/2.0.x/> * boto3 Documentation: <https://boto3.amazonaws.com/v1/documentation/api/latest/index.html> **Next Topic:** Introduction to asynchronous programming in Flask. Please leave a comment below if you have any questions or need help with this topic.