We implement `ToSql` and `FromSql` for `time::Timespec` values. Our
documentation indicates that we store the value in the same format
used by SQLite's built-in date/time functions, but this was not
correct.
We were using the format:
%Y-%m-%d %H:%M:%S:%f %Z
This format cannot be interpreted at all by SQLite's built-in
date/time functions. There are three reasons for this:
- SQLite supports only two timezone formats: `[+-]HH:MM` and the
literal character `Z` (indicating UTC)
- SQLite does not support a space before the timezone indicator
- SQLite supports a period (`.`) between the seconds field and the
fractional seconds field, but not a colon (`:`)
SQLite does support the RFC 3339 date/time format, which is standard
in many other places. As we're always storing a UTC value, we'll
simply use a trailing `Z` to indicate the timezone, as allowed by RFC
3339. The new format is:
%Y-%m-%dT%H:%M:%S.%fZ
To avoid breaking applications using databases with values in the old
format, we'll continue to support it as a fallback for `FromSql`.
[1] https://www.sqlite.org/lang_datefunc.html
[2] https://tools.ietf.org/html/rfc3339
Pass implementers a BorrowedValue instead of relying on them to use
the FFI interface. We take the responsibility of converting the raw
statement and column index into a BorrowedValue.
