Books Flask App

Here’s how you can design a simple RESTful API for a book management system using Flask. This API will include routes for adding, retrieving, updating, and deleting books. For simplicity, I'll store the book data in an in-memory dictionary.

Steps:

1. Install Flask (if you don’t have it):

   bash
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   pip install flask
   

2. Create a basic Flask app with the following routes:

   • POST /books: Add a new book.
   • GET /books: Get all books.
   • GET /books/<id>: Get a book by its ID.
   • PUT /books/<id>: Update a book's details.
   • DELETE /books/<id>: Delete a book by its ID.

Code:

python
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from flask import Flask, jsonify, request, abort

app = Flask(__name__)

# In-memory database (dictionary) for storing books
books = {}

# Helper function to generate a unique book ID
def generate_id():
    return max(books.keys(), default=0) + 1

# Route to add a new book
@app.route('/books', methods=['POST'])
def add_book():
    if not request.json or 'title' not in request.json:
        abort(400, description="Book title is required")

    book_id = generate_id()
    new_book = {
        'id': book_id,
        'title': request.json['title'],
        'author': request.json.get('author', "Unknown"),
        'published_year': request.json.get('published_year', "N/A")
    }
    books[book_id] = new_book
    return jsonify(new_book), 201

# Route to get all books
@app.route('/books', methods=['GET'])
def get_books():
    return jsonify(list(books.values()))

# Route to get a specific book by ID
@app.route('/books/<int:book_id>', methods=['GET'])
def get_book(book_id):
    book = books.get(book_id)
    if book is None:
        abort(404, description="Book not found")
    return jsonify(book)

# Route to update a book by ID
@app.route('/books/<int:book_id>', methods=['PUT'])
def update_book(book_id):
    if not request.json:
        abort(400, description="Bad request. JSON data is required")
    
    book = books.get(book_id)
    if book is None:
        abort(404, description="Book not found")

    # Update book details based on the provided fields
    book['title'] = request.json.get('title', book['title'])
    book['author'] = request.json.get('author', book['author'])
    book['published_year'] = request.json.get('published_year', book['published_year'])
    
    books[book_id] = book
    return jsonify(book)

# Route to delete a book by ID
@app.route('/books/<int:book_id>', methods=['DELETE'])
def delete_book(book_id):
    book = books.pop(book_id, None)
    if book is None:
        abort(404, description="Book not found")
    return jsonify({'result': 'Book deleted successfully'})

# Error handler for 404 errors
@app.errorhandler(404)
def not_found(error):
    return jsonify({'error': str(error)}), 404

# Error handler for 400 errors
@app.errorhandler(400)
def bad_request(error):
    return jsonify({'error': str(error)}), 400

# Run the Flask app
if __name__ == '__main__':
    app.run(debug=True)

Features:

• POST /books: Add a new book by sending a JSON payload.
  • Example request payload:

    json
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    {
        "title": "The Great Gatsby",
        "author": "F. Scott Fitzgerald",
        "published_year": 1925
    }
    

• GET /books: Retrieve all books in the system.
• GET /books/<id>: Retrieve a specific book by its ID.
• PUT /books/<id>: Update the details of a book by its ID (partial updates allowed).
  • Example request payload:

    json
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    {
        "title": "The Great Gatsby - Updated"
    }
    

• DELETE /books/<id>: Remove a book by its ID.

Example Usage:

• Add a book:

  bash
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  curl -X POST -H "Content-Type: application/json" -d '{"title": "1984", "author": "George Orwell", "published_year": 1949}' http://127.0.0.1:5000/books
  

• Get all books:

  bash
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  curl http://127.0.0.1:5000/books
  

• Get a book by ID:

  bash
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  curl http://127.0.0.1:5000/books/1
  

• Update a book by ID:

  bash
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  curl -X PUT -H "Content-Type: application/json" -d '{"title": "Animal Farm"}' http://127.0.0.1:5000/books/1
  

• Delete a book by ID:

  bash
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  curl -X DELETE http://127.0.0.1:5000/books/1
  

Running the Application:

1. Save the Python script to a file (e.g., app.py).
2. Run the Flask app:

   bash
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   python app.py
   

3. Access the API on http://127.0.0.1:5000.

This is a simple implementation and doesn't persist data. In a real-world application, you could use a database (like SQLite, PostgreSQL, etc.) for storage. You could also add authentication, pagination, and better error handling for a more robust API.