Replace days with dates, naming the exact dates to fetch

[chross22]

Why

days took day-of-month numbers and applied them to every requested month. That describes a sampling rule, not a set of dates. Survey dates are not a rule — they fall on the 3rd in January and the 17th in February, and no day-number selection expresses that.

Matching daily data to observations was the point of daily support, and days could not do it.

accessEnvDat(vars = "SST", dates = unique(observations$date), bounding_box = bb)

YYYYMMDD strings, YYYY-MM-DD strings, Date objects, and YYYYMMDD numbers are all accepted. Dates are sorted and deduplicated. A date the calendar does not have is an error naming it, since dropping it would fetch fewer days than were asked for and say nothing.

Because dates names the time steps, years and months are no longer required, and passing them alongside it is an error rather than two answers to one question with no rule for which wins.

A matching bug this exposed

detect_temporal_resolution() reads daily data from more than one day within a month. A set of survey dates — one per month — is indistinguishable from monthly data by that test, so matchData() would join by month and ignore the day. That is the opposite of why anyone passes dates.

accessEnvDat() knows which dataset it fetched, so it now records the step on the result and the detector trusts that over its heuristics. An explicit temporal_resolution still overrides both.

Caught by testing against the live API rather than by reading — the fetch looked right and the resolution was wrong.

One trap named in the error text

c() on a mixture of strings and Dates converts the Dates to days-since-1970 before the function sees them. Being told that 18310 is not a date is unhelpful without the cause, so that case is diagnosed specifically.

Verification

Live API: three dates on different days of three months fetch those days, come back as daily, and match observations on exactly those dates.

  YEAR MONTH DAY n      SST
  2010     1   3 1 6.900449
  2010     2  17 2 5.470718
  2010     3  26 3 5.130863

• R CMD check — Status: OK. Full suite green; the days test block is replaced by 13 dates tests covering input forms, sorting, dedupe, invalid dates, the c() coercion trap, the contradictions, and the recorded step.
• Installed into both R 4.6.1 and 4.3.2.

Breaking

days is removed rather than deprecated — it landed today, is unreleased, and the two arguments mean different things, so an alias would be a rule masquerading as a date list.

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