We want to query for service usage in the BST financial year:
2022-04-01T00:00:00+01:00 to 2023-03-31T23:59:59+01:00 =>
2022-04-01 to 2023-03-31 # bst_date
Previously we were only doing this explicitly for the monthly API
and it seemed like the yearly usage API was incorrectly querying:
2022-03-31T23:00:00+00:00 to 2023-03-30T23:00:00+00:00 =>
2022-03-31 to 2023-03-30 # "bst_date"
However, it turns out this isn't a problem for two reasons:
1. We've been lucky that none of our rates have changed since 2017,
which is long ago enough that no one would care.
2. There's a quirk somewhere in Sqlalchemy / Postgres that has been
compensating for the lack of explicit BST conversion.
To help ensure we do this consistently in future I've DRYed-up the
BST conversion into a new utility. I could have just hard-coded the
dates but it seemed strange to have the knowledge twice.
I've also adjusted the tests so they detect if we accidentally use
data from a different financial year. (2) is why none of the test
assertions actually need changing and users won't be affected.
Sqlalchemy / Postgres quirk
===========================
The following queries were run on the same data but results differ:
FactBilling.query.filter(FactBilling.bst_date >= datetime(2021,3,31,23,0), FactBilling.bst_date <= '2021-04-05').order_by(FactBilling.bst_date).first().bst_date
datetime.date(2021, 4, 1)
FactBilling.query.filter(FactBilling.bst_date >= '2021-03-31 23:00:00', FactBilling.bst_date <= '2021-04-05').order_by(FactBilling.bst_date).first().bst_date
datetime.date(2021, 3, 31)
Looking at the actual query for the first item above still suggests
the results should be the same, but for the use of "timestamp".
SELECT ...
FROM ft_billing
WHERE ft_billing.service_id = '16b60315-9dab-45d3-a609-e871fbbf5345'::uuid AND ft_billing.bst_date >= '2016-03-31T23:00:00'::timestamp AND ft_billing.bst_date <= '2017-03-31T22:59:59.999999'::timestamp AND ft_billing.notification_type IN ('email', 'letter') GROUP BY ft_billing.rate, ft_billing.notification_type UNION ALL SELECT sum(ft_billing.notifications_sent) AS notifications_sent, sum(ft_billing.billable_units * ft_billing.rate_multiplier) AS billable_units, ft_billing.rate AS ft_billing_rate, ft_billing.notification_type AS ft_billing_notification_type
FROM ft_billing
WHERE ft_billing.service_id = '16b60315-9dab-45d3-a609-e871fbbf5345'::uuid AND ft_billing.bst_date >= '2016-03-31T23:00:00'::timestamp AND ft_billing.bst_date <= '2017-03-31T22:59:59.999999'::timestamp AND ft_billing.notification_type = 'sms' GROUP BY ft_billing.rate, ft_billing.notification_type) AS anon_1 ORDER BY anon_1.notification_type, anon_1.rate
If we try some manual queries with and without '::timestamp' we get:
select distinct(bst_date) from ft_billing where bst_date >= '2022-04-20T23:00:00' order by bst_date desc;
bst_date
------------
2022-04-21
2022-04-20
select distinct(bst_date) from ft_billing where bst_date >= '2022-04-20T23:00:00'::timestamp order by bst_date desc;
bst_date
------------
2022-04-21
2022-04-20
It looks like this is happening because all client connections are
aware of the local timezone, and naive datetimes are interpreted as
being in UTC - not necessarily true, but saves us here!
The monthly API datetimes were pre-converted to dates, so none of
this was relevant for deciding exactly which date to use.
bst_date is a date field. Comparing dates with datetimes in postgres
gets confusing and dangerous. See this example, where a date evaluates
as older than midnight that same day.
```
notification_api=# select '2019-04-01' >= '2019-04-01 00:00';
?column?
----------
f
(1 row)
```
By only using dates everywhere, we reduce the chance of these bugs
happening
Bumped notifications-utils to 3.7.0. Version 3.7.0 includes the
`convert_utc_to_bst` and `convert_bst_to_utc` functions and the
`LETTER_PROCESSING_DEADLINE` constant, so these have been removed from
this repo and anywhere using these has now been updated to get these
from `notifications-utils`.
Also bumped pytest by a patch version to bring in a bug fix.
- moved get_current_financial_year_start_year from service.utils to dao.date_utils
- Moved logic for data persistence from rest to dao when updating records in db
This is still a work in progress but it would be good to get some eyes on it.
This commit includes creating and updating a row in the monthly billing table and a method to fetch the results.
There is a command to populate the monthly billing for a service and month so we can try it out.
The total cost at the moment are wrong, they do not take into account the free allowance - see notes below about adding that to the table.
Left to do:
create a nightly task to run to update the monthly totals.
create an endpoint to return the yearly billing, the current day will need to be calculated on the fly and added to the totals.
Add the free allowance into the total costs.
Once we have the new columns in notifications table, the query will need to include the rate multiplier and if the number is international.
The monthly billing query will be built next.
