A ledger supports multiple commodities. So it is also a inventory management system. There is no differentiation between commodity and currencies.
There are 4 different objects.
- account
- transaction
- entry
- commodity
Account, Transaction, Entry and Commodity.
A transaction is a list of entries that is balanced. That is summing everything by converted commodity, we obtain 0 in each commodity.
An entry is a change in the account, and a conversion, associated with a single transaction.
So it requires a 5 tuple.
account, change, commodity_type_1, converted, commodity_type_2, transaction
This means for an account, change the amount of commodity_type_1 by change.
It also convert change commodity_type_1 into converted commodity_type_2.
If there is no conversion, then change=converted, and commodity_type_1 = commodity_type_2.
Note we do not have any checks on conversions, so one should be aware about entering conversions.
The API would include creating writing a transaction, creating an account, creating an commodity. Transaction updates need to be very careful, as it requires the transaction to be balanced all the time.
psycopg2-binary, sqlachemy