EWS returns “Custom Time Zone” - how to store it in SQL?

问题

When using the EWS GetUserAvailability() function, I get in the AttendeesAvailability[i] object a WorkingHours object containing a Start, an End, the WeekDays, and a TimeZoneInfo object.

For me, the TimeZoneInfo object always has the name Custom Timezone and a GUID as ID, so I cannot restore the very same time zone using FindSystemTimeZoneById.

The time zone that the user can select for his availability, however, is one of the system time zones, so I really expected to find a system time zone returned here. How can I find - from EWS - which system time zone the user has selected in his Outlook or OWA account settings?

If I can't, what is the appropriate way to store a TimeZoneInfo object in SQL server?

回答1:

I have since found out that the problem is the EWS XML format. As can be seen here, it does not contain the full time zone information (e.g. name), only a subset:

  <TimeZone>
    <Bias>480</Bias>
    <StandardTime>
      <Bias>0</Bias>
      <Time>02:00:00</Time>
      <DayOrder>5</DayOrder>
      <Month>10</Month>
      <DayOfWeek>Sunday</DayOfWeek>
    </StandardTime>
    <DaylightTime>
      <Bias>-60</Bias>
      <Time>02:00:00</Time>
      <DayOrder>1</DayOrder>
      <Month>4</Month>
      <DayOfWeek>Sunday</DayOfWeek>
    </DaylightTime>
  </TimeZone>

This subset is then parsed back into a time zone in this EWS Managed API code, with this really useful Guid "Id" (the Id is different every time I call GetUserAvailability, although the timezone is still the same):

return TimeZoneInfo.CreateCustomTimeZone(
    Guid.NewGuid().ToString(),
    -this.bias,
    "Custom time zone",
    "Standard time",
    "Daylight time",
    new TimeZoneInfo.AdjustmentRule[] { adjustmentRule });

So I guess I can expect that in 99% of the cases I will find one or more matching time zones in the list of available system time zones, and I am for now using the extension method:

public static TimeZoneInfo ToSystemTimeZone(this TimeZoneInfo customTimeZone)
{
    var tz = TimeZoneInfo.GetSystemTimeZones().FirstOrDefault(x => x.HasSameRules(customTimeZone));
    if (tz != null) return tz;
    else return customTimeZone;
}

This provides the first system time zone that has the same rules as the custom time zone. It's not a 100% match, since there may be multiple time zones with the same rules, but at least this should keep all the time zone information that is exposed via EWS.

来源：https://stackoverflow.com/questions/37702790/ews-returns-custom-time-zone-how-to-store-it-in-sql

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