Add PATCH method to /api/books/[id] for updating book title and author

Created by: yosuasilalahi-jitera

Overview

This pull request adds support for the PATCH HTTP method to the /api/books/[id] endpoint. The new functionality allows clients to update the title and/or author fields of a book by its id. The implementation continues to use in-memory storage for demonstration purposes.

Changes

• PATCH Method Handling:

  • The API now accepts PATCH requests to /api/books/:id.
  • The request body can include title and/or author fields.
  • At least one of these fields must be provided; otherwise, a 400 Bad Request error is returned.

• Validation and Error Handling:

  • Validates that the id parameter is a string.
  • Checks that the book exists; returns 404 if not found.
  • Ensures at least one updatable field is present in the request body.
  • Returns appropriate error messages for invalid input or missing book.

• Book Update Logic:

  • Updates the specified fields (title and/or author) in the in-memory book object.
  • Returns the updated book object in the response.

• Allowed Methods:

  • The endpoint now explicitly allows only PATCH and DELETE methods.
  • Returns 405 Method Not Allowed for unsupported methods.

Notes

• This implementation is for demonstration and testing purposes only.
• For production, replace the in-memory storage with a persistent database (e.g., MongoDB) and add authentication, authorization, and validation as needed.