Storing TimeSpan Properties with EntityFramework Code First

30 April 2013

Entity Framework 5 Code First does a good job of selecting a corresponding SQL column type for most C# primitives. However, the type it chooses for TimeSpan properties can cause problems. It chooses the Time type which can only store ranges up to 24 hours. If your TimeSpan needs to store more than 24 hours, you need to choose a different option.

The strategy I’ve found most useful is to store the data as Ticks in a BIGINT column. You can achieve this by using the code below

[NotMapped]
public TimeSpan TimeToCompleteForm
{
  get;
  set;
}

public long TimeToCompleteFormTicks
{
  get
  {
    return TimeToCompleteForm.Ticks;
  }
  set
  {
    TimeToCompleteForm = TimeSpan.FromTicks( value );
  }
}

In SQL you can query this value as raw ticks or convert it to a readable string in the format 'dd.hh:mm:ss:ms' using the following query:

SELECT CONVERT(VARCHAR, DATEPART(DAY,DATEADD(ms, TimeToCompleteFormTicks/10000, 0))) + '.' + CONVERT(VARCHAR, DATEADD(ms, TimeToCompleteFormTicks/10000, 0), 114)

Finally, if you prefer to represent the value in milliseconds instead of ticks, the code above requires two tweaks. Instead of Ticks use the TotalMilliseconds property of the TimeSpan. Additionally, use the FromMilliseconds method to convert the incoming milliseconds to a TimeSpan instead of FromTicks.

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