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POST
/
books
/
{isbn}
/
user
/
{user_id}
curl -X POST https://api.example.com/books/978-0-12345-678-9/user/42 \
  -u "username:password" \
  -H "Content-Type: application/json"

{
  "id": 123,
  "user": {
    "id": 42,
    "firstname": "John",
    "lastname": "Doe",
    "email": "[email protected]",
    "displayPicture": "https://example.com/photos/john.jpg"
  },
  "book": {
    "isbn": "978-0-12345-678-9",
    "title": "The Great Adventure",
    "stock": 4,
    "coverImage": "https://example.com/covers/great-adventure.jpg",
    "author": {
      "id": 7,
      "name": "Jane Smith",
      "age": 45
    }
  },
  "loanDate": "2026-03-04T10:30:00Z",
  "returnDate": "2026-03-18T10:30:00Z",
  "returned": false
}

​
Authentication

This endpoint requires HTTP Basic Authentication.

​
Path Parameters

​
isbn
string
required
The ISBN of the book to rent
​
user_id
integer
required
The ID of the user renting the book

​
Response

​
id
integer
Unique identifier for the rental
​
user
object
User who rented the book
​
id
integer
User ID
​
firstname
string
User’s first name
​
lastname
string
User’s last name
​
email
string
User’s email address
​
displayPicture
string
URL to user’s display picture
​
book
object
Book being rented
​
isbn
string
Book ISBN
​
title
string
Book title
​
stock
integer
Current stock count (decremented by 1 after rental)
​
coverImage
string
URL to book cover image
​
author
object
Book author details
​
id
integer
Author ID
​
name
string
Author name
​
age
integer
Author age
​
loanDate
string
ISO 8601 timestamp when the book was rented (UTC)
​
returnDate
string
ISO 8601 timestamp when the book is due (2 weeks from loan date)
​
returned
boolean
Whether the book has been returned (always false for new rentals)

​
Error Responses

​
404
error
Book with the specified ISBN or user with the specified ID not found
​
400
error
Book is out of stock (stock = 0)

​
Automatic Stock Management

When a rental is created, the book’s stock is automatically decremented by 1. If the book has no stock available (stock = 0), the request will fail with a 400 Bad Request error.

​
Loan Period

All rentals have a 2-week loan period. The returnDate is automatically set to 2 weeks (14 days) from the loanDate. 
curl -X POST https://api.example.com/books/978-0-12345-678-9/user/42 \
  -u "username:password" \
  -H "Content-Type: application/json"

{
  "id": 123,
  "user": {
    "id": 42,
    "firstname": "John",
    "lastname": "Doe",
    "email": "[email protected]",
    "displayPicture": "https://example.com/photos/john.jpg"
  },
  "book": {
    "isbn": "978-0-12345-678-9",
    "title": "The Great Adventure",
    "stock": 4,
    "coverImage": "https://example.com/covers/great-adventure.jpg",
    "author": {
      "id": 7,
      "name": "Jane Smith",
      "age": 45
    }
  },
  "loanDate": "2026-03-04T10:30:00Z",
  "returnDate": "2026-03-18T10:30:00Z",
  "returned": false
}

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