Sam Goods: Online shopping

This is the REST API for the backend of Sam Goods: Online shopping and invoice generator.

The Task

The task required developing a REST API for a goods website enabled with the functionality of adding desirable items to a list and then getting the invoice of that list.

Approach

I used django and djangorestframework for the same. The database used was postgresql.

Models

The initial stages of the task involved developing two models.
- Item
- List
The Item model contains information such as name, price, and available_stock of the corressponding item, and also contains a ForeignKey reference to the List table.
The List model just contains a name and is implemented in a way so as to maintain only a single List in the database at all times.

Views

Then I developed the views using the APIView class imported from rest_framework library.
Simple GET and POST requests were handled to get all items in the database and to post new items to the database.
GET request view to the "Get List" endpoint is responsible for keeping a single list in the database.
POST request view for the list handles adding new items to the list.
PUT request view for the list handles any updates made to the list.

Endpoints

GET Items This endpoint returns the list of items along with their prices and available quantity in the database. A post request to this endpoint with the following JSON format adds a new item to the database.
```
{
    "name": "Bag",
    "quantity": 69,
    "price": 420
}
```
PS: If quantity or/and price are not specified, they are set to 100 by default.
GET List This endpoint creates a primary list or returns the list that is already on the database.

A POST request to the same endpoint with the below format adds the specified items to the list.
```
{
    "name": "Bag",
    "quantity": 30
}
```
Both name and quantity are required fields in this POST request.
A PUT request to the same endpoint is used to update the items in the list and NOT add new items to the list.
- The format for updating the quantity of an a item called "Bag" with new quantity 69 is given below
```
{
    "name": "Bag",
    "quantity": 69
}
```
- To delete the item "Bag" from the list, use
```
{
    "name": "Bag",
    "delete": 1
}
```
Setting the value of delete key to 0 does not result in any update.