I've written some code to read a column of data from a dataset called AltIds. The values are nullable. My code is written to find all the values in the column that are not null and write them to an array.

Guid[] altIds = myDataSet.Tables[0].AsEnumerable()
  .Select(row => row.Field<Guid?>("AltId"))
  .Where(x => x.HasValue)

The code works, but it seems a bit complicated. Is there a better way to do this?


2 Answers 2


What you have is fine. You could restructure it to eliminate one of the selects, but then you would repeat yourself with the row.

var altIds = myDataSet.Tables[0].AsEnumerable()
                 .Where(row => row.Field<Guid?>("AltId").HasValue)
                 .Select(row => row.Field<Guid?>("AltId").Value)

You could rewrite it in query expression syntax, but that's only less complicated if you find fluent syntax more so.

var altIds = (from row in myDataSet.Tables[0].AsEnumerable()
             let x = row.Field<Guid?>("AltId")
             where x.HasValue
             select x.Value).ToArray();

Either way, it's six in one hand, half a dozen in the other. I find your code readable, and it passes the "does what it is supposed to" test, so I wouldn't worry about this snippet.


This is terribly nit picky, but the whitespace is inconsistent. Give this line some breathing space.


In a larger sample of code, this kind of thing becomes hard to read.


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