Linq All on empty collection

Question

I need to check if all definitions contains some specific data. It works fine except the case when GroupBy returns empty collection.

var exist = dbContext.De         


        

Answer 1

You could make use of DefaultIfEmpty extension method, and adjust your some condition so that it evaluates null to false.

var exist = definitions
    .Where(x => propertyTypeIds.Contains(x.PropertyTypeId) && x.CountryId == countryId)
    .GroupBy(x => x.PropertyTypeId)
    .DefaultIfEmpty()
    .All(...some condition...));

Answer 2

Well, you can do it in two steps :

var definitions = definitions.Where(
                    x => propertyTypeIds.Contains(x.PropertyTypeId) && x.CountryId == countryId)
                     .GroupBy(x => x.PropertyTypeId);

var exist = definitions.Any() && definitions.All(...some condition...);