How do I store a negative TimeSpan in Entity Framework?

Question

How do I store a negative TimeSpan in Entity Framework?

David Thielen 3,211

Hi all;

I store shifts to events with a TimeSpan as the offset from the start of the event and another TimeSpan as the duration of the shift. The setup shift starts before the event (so everyone see the event as 11:00am - 4:00pm as desired while the setup shift starts at 10:15am).

Entity Framework throws an exception saving a TimeSpan < 0 or >= 24:00:00. Is there a way to save a TimeSpan outside the 0 .. 24 hour range?

thanks - dave

AgaveJoe 30,126 Reputation points

2024-06-02T13:01:45.4233333+00:00

The C# TimeStamp is the different between two dates which can be zero or more. There no such thing as a negative TimeSpan because we cannot go backwards in time. A C# TimeSpan is mapped to a [time] type in T-SQL. The T-SQL [time] type has a range of 00:00:00.0000000 through 23:59:59.9999999.

The simple solution is using an int rather than a TimeSpan. Secondly, you are doing DateTime math not TimeSpan. You want to AddMinutes(-45) to a start DateTime for the setup crew.
David Thielen 3,211 Reputation points

2024-06-02T15:32:42.07+00:00

You can go backwards in time. You just need a flux capacitor.

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AgaveJoe 30,126 Reputation points

2024-06-02T13:01:45.4233333+00:00

The C# TimeStamp is the different between two dates which can be zero or more. There no such thing as a negative TimeSpan because we cannot go backwards in time. A C# TimeSpan is mapped to a [time] type in T-SQL. The T-SQL [time] type has a range of 00:00:00.0000000 through 23:59:59.9999999.

The simple solution is using an int rather than a TimeSpan. Secondly, you are doing DateTime math not TimeSpan. You want to AddMinutes(-45) to a start DateTime for the setup crew.
David Thielen 3,211 Reputation points

2024-06-02T15:32:42.07+00:00

You can go backwards in time. You just need a flux capacitor.

Answer 1

Bruce (SqlWork.com) 77,686 Volunteer Moderator

Your issue is the default mapping of TimeSpan is to sql Time, which is a time, not a time period. But EF supports mapping a TimeSpan to a long, and will convert the TimeSpan to ticks, which is a period and can be negative.

https://learn.microsoft.com/en-us/ef/core/modeling/value-conversions?tabs=data-annotations

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How do I store a negative TimeSpan in Entity Framework?

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