Important End Points -> /api/transactions/ -> /api/verify/str:Card_number

Database Structure 3 Models -> Cards -> Items -> Transaction -> has Foreign Key Relation with Cards and Items

Endpoint Description -> /api/transactions/

Most important Endpoint. When data is send to the this end point from the NodeMCU In the following format. { "Card_number": "abcdef", (needs to be string)
"Number_of_Items":10000, (needs to be integer) "Item_Retrieved": 1 (needs to be integer) }

Card_number is checked by server from the Cards table i.e. if the card is in database it will be verified or else it wont be verified. Number_of_Items is the number of the items that user wants to receive. It will be verified first if the amoint is available then only the transaction will be proceeded. Item_Retrived is the id of the items that is going to be retrived.

In above JSON data if the card_number "abcdef" is in the database and number of items of item_retrived (id = 1, lets say i.e. paper) is equal to or less than required than only item will be dispensed.