using LINQ convertAll when some conversions may be null

i have the following code

          people = positions.ConvertAll(r=> r.Person).ToList();

but in some cases "Person" is going to be null, in these cases i simply don't want to add them into开发者_如何学Python the converted collection (i dont want null items)

what is the best way of achieving this. Can you have a conditional convertall ??

With LINQ, you can do:

positions.Where(r => r.Person != null)
         .Select(r => r.Person)
         .ToList();

The ConvertAll method is not part of LINQ; it's an instance method on List<T>. If you want to stick with that, you can do:

positions.FindAll(r => r.Person != null)
         .ConvertAll(r => r.Person);

Do note that this is subtly different because the result of the filter and the projection are both List<T>s, rather than streaming queries. The final result should be the same though.

people = positions
.Where(r => r.Person !=null).ToList()
.ConvertAll(r=> r.Person);

Use Where to filter out the null occurrences then use Select:

people = positions.Where(p => p.Person != null).Select(r => r.Person).ToList();