c# - Selecting a DTO object from an entity framework query where most properties are the same, is there a better way?

Question

So, I have the following EF query:

private List<PolysubByYearDto> buildDtos(IQueryable<vw_Polysub> polysubs)
        {
            var query = from p in polysubs
                         join c in uowTr.CountyRepository.List() on p.primary_cty equals c.County_Code into lj1
                         from polysubWithCounty in lj1.DefaultIfEmpty()
                         join t in uowTr.PolysubRepository.ListPolyType() on p.poly_type_cd equals t.poly_type_cd into lj2
                         from polysubWithType in lj2.DefaultIfEmpty()
                         join period in uowTr.PolysubRepository.ListReportPeriods() on p.rec_no equals period.rec_no into lj3
                         from polysubWithPeriod in lj3.DefaultIfEmpty()
                        select new PolysubByYearDto()
                        {
                            PrimaryCountyName = (polysubWithCounty == null ? String.Empty : polysubWithCounty.county_name),
                            PolyTypeName = (polysubWithType == null ? String.Empty : polysubWithType.poly_name_ds),
                            ReportYearEndMonth = ((polysubWithPeriod == null || !polysubWithPeriod.year_end_month.HasValue) ? 0 : polysubWithPeriod.year_end_month.Value),
                            taxrate_year = p.taxrate_year
                            //taxrate_year and every property to follow (a lot) are all from the vw_Polysub object
                            //and share the same names as the PolysubByYearDto object properties...
                            // is there a better way to just make them all map without explicitly naming all properties?
                        };

            return query.ToList();
        }

The comment inside the "select" explains my problem. The PolysubByYearDto class is a child of vw_Polysub so it contains all of the same properties plus 3 more. Those 3 properties are set from joined data in the query, but every single property afterward just requires parent to child object property mapping. There are many properties and they all share the same names. Is there a way to do this without explicitly naming every property? The vw_Polysub object is generated from a view so it doesn't have reference properties which is why I had to join the data. I do not want to .toList() the query and then use reflection/automapper to map the properties because of performance reasons, I want the PolysubByYearDto objects to come out of the database. Thanks!

question from:https://stackoverflow.com/questions/65849242/selecting-a-dto-object-from-an-entity-framework-query-where-most-properties-are

Answer 1

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