"purchase_id": 1, "customer_id": 1,
{“index”: 0, "name": "Orange", "quantity": 3, "unit_price": 0.25},
{“index”: 1, "name": "Banana", "quantity": 4, "price": 0.1}
{ "name": "Orange", "quantity": 3, "unit_price": 0.25},
{ "name": "Banana", "quantity": 4, "price": 0.1}
"purchase_id": 2, "customer_id": 1,
“index” : 0, "name": "Apple", "quantity": 1, "unit_price": 0.5}
{ "name": "Apple", "quantity": 1, "unit_price": 0.5}
"purchase_id": 1, "customer_id": 1,
{“index” : 0, "name": "Orange", "quantity": -2, "unit_price": 0.25}
{ "name": "Orange", "quantity": -2, "unit_price": 0.25}