Add DateOnly/TimeOnly to What's New in EF8 #4245
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| ### DateOnly/TimeOnly supported on SQL Server | ||
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| The <xref:System.DateOnly> and <xref:System.TimeOnly> types were introduced in .NET 6 and have been supported for several database providers (e.g. SQLite, MySQL, and PostgreSQL) since their introduction. For SQL Server, the recent release of a [Microsoft.Data.SqlClient](https://www.nuget.org/packages/Microsoft.Data.SqlClient/) package targeting .NET 6 has allowed [ErikEJ to add support for these types at the ADO.NET level](https://github.com/dotnet/SqlClient/pull/1813). This in turn paved the way for support in EF8 for `DateOnly` and `TimeOnly` as properties in entity types. | ||
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Mention support is also available for EF Core 6/7 ? 😄
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Yeah, a note seems to be a good idea.
| > The code shown here comes from [DateOnlyTimeOnlySample.cs](https://github.com/dotnet/EntityFramework.Docs/tree/main/samples/core/Miscellaneous/NewInEFCore8/DateOnlyTimeOnlySample.cs). | ||
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| > [!NOTE] | ||
| > This model represents only British schools and stores times as local (GMT) times. Handling different timezones would complicate this code significantly. Note that using `DateTimeOffset` would not help here, since opening and closing times have different offsets depending whether daylight saving time is active or not. |
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FWIW unless I'm mistaken, this could be made international simply by introducing a timezone column in the table, so that we know what timezone each school is in. Then, the e.g. opening hour is always interpreted with respect to that timezone. But I agree it's not worth going into that here.
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What's the recommended way of writing queries against that? Presumably, I would use a UTC time as the parameter, but then convert the column value to UTC in the query? How would I do that conversion--is there a .NET BCL way of doing, or do I need to use a database-specific function? Also, the conversion will be dependent on the day for which the query is running, since it will give a different UTC depending on daylight saving or not. And finally, I would need to be sure that overflow to the next/previous day didn't return incorrect results.
I gave up! :-)
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Ahahaha yeah time zone stuff is always awesome :)
So that's why we added EF.Functions.AtTimeZone for SQL Server. The PG provider does translate various BCL APIs because they're a good fit (see these docs, scroll down a bit).
But you're right that you can't do time zone conversion on just a time - you need a full timestamp (8:00AM converts to different times in other time zones e.g. based on daylight savings). So if the goal is e.g. to get a UTC time for the school opening (for whatever reason), the query would need to construct a timestamp from the database time - providing some date as appropriate - convert that to UTC (with AtTimeZone), and then extract the time component out of that. I think we should have all the building blocks for that, but I'm not 100% sure.
(either way, I definitely think we\ don't need to go into all this complexity in an intro to DateOnly/TimeOnly!).
| ### DateOnly/TimeOnly supported on SQL Server | ||
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| The <xref:System.DateOnly> and <xref:System.TimeOnly> types were introduced in .NET 6 and have been supported for several database providers (e.g. SQLite, MySQL, and PostgreSQL) since their introduction. For SQL Server, the recent release of a [Microsoft.Data.SqlClient](https://www.nuget.org/packages/Microsoft.Data.SqlClient/) package targeting .NET 6 has allowed [ErikEJ to add support for these types at the ADO.NET level](https://github.com/dotnet/SqlClient/pull/1813). This in turn paved the way for support in EF8 for `DateOnly` and `TimeOnly` as properties in entity types. | ||
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Yeah, a note seems to be a good idea.
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