Library - Flask Practice

For this assessment, you'll be working with a Library book loan domain.

In this repo:

There is a Flask application with some features built out.

You can either check your API by:

Using Postman to make requests
Building out a React frontend

Setup

To download the dependencies, run:

pipenv install
pipenv shell

You can run your Flask API on localhost:5555 by running:

python server/app.py

Your job is to build out the Flask API to add the functionality described in the deliverables below.

Models

You will implement an API for the following data model:

The file server/models.py defines the model classes without relationships. Use the following commands to create the initial database app.db:

export FLASK_APP=server/app.py
flask db init
flask db upgrade head

Now you can implement the relationships as shown in the ER Diagram:

A Member has many Books through Loan
A Book has many Members through Loan
A Loan belongs to a Member and belongs to a Book

Update server/models.py to establish the model relationships. Since a Loan belongs to a Member and a Book, configure the model to cascade deletes.

Set serialization rules to limit the recursion depth.

Run the migrations and seed the database:

flask db revision --autogenerate -m 'message'
or 
flask db migrate -m 'message'
flask db upgrade head
python server/seed.py

If you aren't able to get the provided seed file working, you are welcome to generate your own seed data to test the application.

Validations

Add validations to the Loan model:

must have a number_of_pages greater than or equal to 1

Routes

Set up the following routes. Make sure to return JSON data in the format specified along with the appropriate HTTP verb.

Recall you can specify fields to include or exclude when serializing a model instance to a dictionary using to_dict() (don't forget the comma if specifying a single field).

NOTE: If you choose to implement a Flask-RESTful app, you need to add code to instantiate the Api class in server/app.py.

GET /books

Return JSON data in the format below:

[
  {
    "author": "Gayle Laakmann McDowell",
    "id": 1,
    "title": "Cracking the Coding Interview"
  },
  {
    "author": "Marijn Haverbeke",
    "id": 2,
    "title": "Eloquent JavaScript"
  },
  {
    "author": "Allen B. Downey",
    "id": 3,
    "title": "Think Python: How to Think Like a Computer Scientist"
  }
]

Recall you can specify fields to include or exclude when serializing a model instance to a dictionary using to_dict() (don't forget the comma if specifying a single field).

GET /books/int:id

If the Book exists, return JSON data in the format below:

{
  "author": "Allen B. Downey",
  "id": 3,
  "title": "Think Python: How to Think Like a Computer Scientist",
  "loans": [
    {
      "id": 1,
      "member": {
        "id": 1,
        "name": "Emma",
        "year_joined": 2023
      },
      "book_id": 3,
      "check_out_date": "2023-11-17 23:32:24",
      "due_date": "2023-11-24 23:32:24",
      "member_id": 1
    }
  ]
}

If the Book does not exist, return the following JSON data, along with the appropriate HTTP status code:

{
  "error": "Book not found"
}

DELETE /books/int:id

If the Book exists, it should be removed from the database, along with any Loans that are associated with it (a Loan belongs to a Book). If you did not set up your models to cascade deletes, you need to delete associated Loans before the Book can be deleted.

After deleting the Book, return an empty response body, along with the appropriate HTTP status code.

If the Book does not exist, return the following JSON data, along with the appropriate HTTP status code:

{
  "error": "Book not found"
}

GET /members

Return JSON data in the format below:

[
  {
    "id": 1,
    "name": "Emma",
    "year_joined": 2023
  },
  {
    "id": 2,
    "name": "Taylor",
    "year_joined": 2023
  },
  {
    "id": 3,
    "name": "Kiki",
    "year_joined": 2023
  }
]

POST /loans

This route should create a new Loan that is associated with an existing Book and Member. It should accept an object with the following properties in the body of the request:

{
  "book_id": 1,
  "member_id": 3
}

If the Loan is created successfully, send back a response with the data related to the Loan:

{
  "id": 1,
  "member": {
    "id": 1,
    "name": "Emma",
    "year_joined": 2023
  },
  "book_id": 3,
  "due_date": 1,
  "check_out_date": 1,
  "book": {
    "author": "Gayle Laakmann McDowell",
    "id": 1,
    "title": "Cracking the Coding Interview",
    "number_of_pages": 100
  },
  "member_id": 1
}

If the Loan is not created successfully due to a validation error, return the following JSON data, along with the appropriate HTTP status code:

{
  "errors": ["validation errors"]
}

emileypalmquist / flask-library-practice