Prices and Costs

Beancount limitation

One limitation of the official beancount data model is that the distinction of total price and unit price disappears during parsing, and therefore with the official library, there is no way to tell which form the original definition uses, to read the total cost, or to output a total cost.

Basic access

Fortunately, autobean-refactor does not have the same issue. In autobean-refactor, there are UnitPrice, TotalPrice, UnitCost, and TotalCost. The Unit- and Total- versions are almost identical except being different type, allowing case distinction.

Price access

To check type:

posting = p.parse('    Assets:Foo 100.00 GBP @@ 130.00 USD', models.Posting)
assert isinstance(posting.price, models.TotalPrice)
assert not isinstance(posting.price, models.UnitPrice)
_print_model(posting)

    Assets:Foo 100.00 GBP @@ 130.00 USD

To read value:

(posting.price.number, posting.price.currency)

(Decimal('130.00'), 'USD')

To modify value:

posting.price.number = decimal.Decimal('135.00')
_print_model(posting)

    Assets:Foo 100.00 GBP @@ 135.00 USD

To flip type:

posting.price = models.UnitPrice.from_value(
    number=posting.price.number / posting.number,
    currency=posting.price.currency)
_print_model(posting)

    Assets:Foo 100.00 GBP @ 1.35 USD

Cost access

The interface for costs is more complex as costs can carry more information.

To check type:

posting = p.parse(
    '    Assets:Foo 100.00 GBP { 1.30 USD, 2000-01-01, "foo", * }',
    models.Posting)
assert isinstance(posting.cost.raw_cost, models.UnitCost)
assert not isinstance(posting.cost.raw_cost, models.TotalCost)
_print_model(posting)

    Assets:Foo 100.00 GBP { 1.30 USD, 2000-01-01, "foo", * }

To read value:

(posting.cost.number_per, posting.cost.number_total, posting.cost.currency)

(Decimal('1.30'), None, 'USD')

To modify value:

posting.cost.number_per = decimal.Decimal('1.35')
posting.cost.label = 'bar'
_print_model(posting)

    Assets:Foo 100.00 GBP { 1.35 USD, 2000-01-01, "bar", * }

To flip type:

num = posting.cost.number_per
posting.cost.number_per = None
posting.cost.number_total = num * posting.number
_print_model(posting)

    Assets:Foo 100.00 GBP {{ 135.0000 USD, 2000-01-01, "bar", * }}