Retrieving A Book By ID - Planning

Refer back to Chapter 6, The Bookstore API Endpoint Specifications, API Endpoint #6: Retrieve a Book Listing section for the API endpoint specifications.

1 - Route Name

Much like how we planned out the URI for retrieving all books, retrieving a single book is not too far off from that. From the specifications, it seems like this will be a GET request that will fetch a single book by its ID. We can refer back to the sections under chapter 3 for guidelines, specifically the sections Method Verbs and URI Design.

The following URI should suffice.

GET /api/v1/books/:id

2 - Input Request

Similar to retrieving all books, there are none.

3 - Middleware

Similar to retrieving all books, there are none.

4 - Validation

Similar to retrieving all books, there are none.

5 - Domain

Similar to the retrieval of all books, we will be using the same 3 entities to orchestrate our domain logic.

• bookModel

• bookRepository

• bookService

We will definitely use the bookRepository and get it a method something like getById().

In the bookService, we would want to have a method as well, perhaps, getBookById(). Also, remember that we want to do some sort of validation to check if the book we are trying to retrieve exists. Recall that we must return a 404 in our response to indicate that a book with the specified ID by the client does not exist.

6 - Events

Similar to retrieving all books, there are none.

7 - Response(s)

There are 2 types of responses that could possibly return from this endpoint.

The first is the book with the specified ID if it does exist in the database.

{
    "status": "success",
    "code": 200,
    "message": "Here is the book with the specified ID."
    "data": {
       "id": "61f88350745d83158f3c746d",
       "title": "Harry Potter and the Goblet of Fire",
       "description": "Mint condition, but will negotiate",
       "price": 99,
       "author": "J.K. Rowling",
       "datePublished": "Sun Oct 10 2021 23:56:34 GMT-0400"
    },
    "errors": null
}

The second is a message indicating to the client that the book with the specified ID does not exist.

{
    "status": "error",
    "code": 404,
    "message": "That book with the specified ID does not exist."
    "data": null,
    "errors": [
        "Book listing not found."
    ]
}