SQL - HighlightIf vs Highlight ?

klundberg · December 2014

Hello,

Would someone please point out why HighlightIf fails below?

( from x in
  // ensure a list of non-null first names
  ( from y in Users .Where (y => y.FirstName.Length>0) select y.FirstName ) .Take(9)
  select new {
    //  works fine:
    //  FirstName=Util.Highlight(x)
    //  fails: "Object reference not set to an instance of an object"
    FirstName=Util.HighlightIf(x, a => a.Contains("a"))
  }
)

Thanks in advance,
Ken

Sorax · December 2014

Apparently the provider is able to infer Highlight is a local method but trips on HighlightIf. Maybe it's the predicate. Not sure but adding AsEnumerable() fixes it:

(from x in
  (from y in Users .Where (y => y.FirstName.Length>0) 
   select y.FirstName) 
  .Take(9)
  .AsEnumerable()
  select new 
  {
    FirstName = Util.HighlightIf(x, a => a.Contains("a"))
  }
)

You might consider fluent syntax:

Users
.Where(a => a.FirstName.Length > 0)
.Select(a => a.FirstName)
.Take(9)
.AsEnumerable()
.Select(a => Util.HighlightIf(a, b => b.Contains("a"))

JoeAlbahari · December 2014

Yes, it's most likely the predicate. AsEnumerable is a good workaround.

klundberg · January 2015

Thank you Sorax and Joe!
I like fluent syntax, but was using (let) query variables in the larger query this snippet came from.

SQL - HighlightIf vs Highlight ?

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