LINQ to Entities for subtracting 2 dates

Admin 1
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I am trying to determine the number of days between 2 dates using LINQ with Entity Framework. It is telling me that it does not recognize Subtract on the System.TimeSpan class

Here is my where portion of the LINQ query.

where ((DateTime.Now.Subtract(vid.CreatedDate).TotalDays < maxAgeInDays))

Here is the error I receive in the VS.NET debugger

{"LINQ to Entities does not recognize the method 'System.TimeSpan Subtract(System.DateTime)' method, and this method cannot be translated into a store expression."}

Am I doing something wrong or is there a better way to get the number of days between 2 DateTimes in the entity framework?

thanks Michael

datetime linq-to-entities entity-framework
6 Answers

Here is how I got it to work

I defined a datetime variable that represents the oldest date

DateTime oldestDate = DateTime.Now.Subtract(new TimeSpan(maxAgeInDays, 0, 0, 0, 0));
...

then I modified the where portion of the LINQ query

where (vid.CreatedDate >= oldestDate )

worked like a charm - thanks Micah for getting me to think about the expression tree

Admin1

You run into these kind of isses because the predicate needs to be translated to an expression tree. And translation process doesn't recognize the DateTime.Now.Subtract method.

Micah_177440
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