使用 ConvertUsing 到 map 并使用 SqlFunctions 进行投影

Question

I am upgrading a .NET Framework project from Automapper 4.1.1 to Automapper 10.0.0 and I am encountering a problem that I am unable to resolve. I see that ConvertUsing and ProjectUsing have been unified, but somehow I have to be able to tell if a Mapping or a Project is being done. I have a configuration so that it is applied generically when changing a DateTime to an int so that it transforms by calculating the number of minutes. I need to use SqlFunctions to do the conversion but only when we are projecting, when we are mapping it must be done through a simple transformation. How can you do this if you can now only have one ConvertUsing?

       CreateMap<DateTime?, int>().ConvertUsing(x => x.HasValue ? System.Data.Entity.SqlServer.SqlFunctions.DatePart("HOUR", x.Value).Value * 60 + System.Data.Entity.SqlServer.SqlFunctions.DatePart("MINUTE", x.Value).Value : 0); CreateMap<DateTime, int>().ConvertUsing(x => System.Data.Entity.SqlServer.SqlFunctions.DatePart("HOUR", x).Value * 60 + System.Data.Entity.SqlServer.SqlFunctions.DatePart("MINUTE", x).Value); CreateMap<DateTime?, int>().ConvertUsing(x => Convert.ToInt32(x.HasValue ? x.Value.TimeOfDay.TotalMinutes : 0)); CreateMap<DateTime, int>().ConvertUsing(x => Convert.ToInt32(x.TimeOfDay.TotalMinutes));

I tried using ProjectUsing or looking for a parameter inside ConvertUsing that tells me if I'm converting an IQueryable but it doesn't seem to exist

Answer 1

You can create custom DB function (using eg CodeFirstFunctions or EntityFramework.Functions package that allows creating custom functions) and provide body of this function (example):

[Function(FunctionType.ComposableScalarValuedFunction, nameof(SecondsDiff), Schema = "dbo")]
[return: Parameter(DbType = "int")]
public static int? SecondsDiff([Parameter(DbType = "date")] DateTime? date1, [Parameter(DbType = "date")] DateTime? date2)
{
    if (date1 == null || date2 == null)
    {
        return null;
    }

    DateTime a = date1.Value;
    DateTime b = date2.Value;

    if (a >= b)
    {
        return (int?)(b - a).TotalSeconds;
    }

    return -(int?)(a - b).TotalSeconds;
}

It will work in both modes.