Station fields

Any $station report tag can be listed as a field, written with the $ removed. The values are evaluated against the exact object behind the report tag (weewx.station.Station), so they render as the report would render them. New in 6.3.

Examples:

station.uptime.raw                WeeWX uptime in seconds
station.uptime.long_form()        e.g., 25 days, 21 hours, 15 minutes
station.os_uptime.raw             server uptime in seconds
station.os_uptime.long_form()
station.version                   the WeeWX version, e.g., 5.4.0
station.python_version
station.hardware                  e.g., Vantage
station.location                  [Station] location from weewx.conf
station.altitude                  e.g., 700 feet
station.altitude.meter.raw        unit conversions work as in report tags
station.latitude                  ["37", "24.00", "N"] — the same (degrees,
                                  minutes, hemisphere) parts the report tag
                                  exposes, as a json array

The point: a restart-correct live uptime

The point of station fields is uptime and os_uptime: they are recomputed on every loop packet, so a live uptime readout is correct within a packet or two of a weewxd or server restart.

The report-cycle alternative — shipping $station.uptime.raw in a template and extrapolating in javascript — is wrong after every restart: it shows the pre-restart uptime still climbing until the next report cycle runs.

Every other $station attribute is constant for the life of the weewxd process; loopdata computes those once and repeats the value in every write, so a page that is not itself a WeeWX report can still show them.

Notes

• Station fields are current-only: no period prefix, no aggregate.
• round(n) and the format specs/calls work as on observation and almanac fields: .raw on uptime/os_uptime/altitude (ValueHelpers), identity on plain values (station.week_start.raw); .formatted, format(...), nolabel(...), string(...), long_form(...) on the ValueHelpers only.
• Unit conversions chain as in report tags: station.altitude.meter.raw.
• A $station attribute whose value is a tuple of scalars (e.g. station.latitude’s degrees/minutes/hemisphere) is emitted as a json array.
• The json key is the field entry verbatim, so element ids can match keys as usual.