LINQ Return null even if it meets condtion

Question

Not sure why it happen, I observed it in debugging mode and condition inside the LINQ has been meet

if (chkSometing.Checked)
{
  var _results = from itemlist in dtResult.AsEnumerable()
                 where itemlist.Field<string>("data_visibility").Contains("both")
                 select itemlist;
  try { dtResult = _results.CopyToDataTable(); }
  catch (Exception ex) { Response.Write(ex.Message); }
}

Possible duplicate of [Fill Datatable from linq query](https://stackoverflow.com/questions/17088779/fill-datatable-from-linq-query) — HEWhoDoesn'tKnow, Nov 09 '18 at 01:54
I'm afraid that it is not the case, Before that query I have successfully convert it to data table. But right now it worked. I change the "Contains" to Equal. Thanks for your time pal — Richard Mark Bonifacio, Nov 09 '18 at 02:10
@RichardMarkBonifacio good work, post your answer for other's future reference. — HEWhoDoesn'tKnow, Nov 09 '18 at 02:22

Gauravsa · Accepted Answer · 2018-11-09T02:48:42.207

2

Although you may have fixed the problem, I can explain why "Contains" didnt work and "Any" will work in this case.

Contains check if the sequence contains an element.

Any checks if any element of sequence satisfies a condition. Its like a predicate.

So, if you wish to check whether an element of a sequence satisfies a condition use "Any". Example below:

List<string> list = new List<string> { "a", "aa", "aaa", "b", "c" };

bool containsBoy = list.Contains("c"); //true
// list.ElementAt(0).Contains("c") // --> Error which is what you are getting

bool anyBoy = list.Any(r => r.Length == 2); // true for "aa"

Source: What is the difference between Contains and Any in LINQ?

edited Nov 09 '18 at 02:48

answered Nov 09 '18 at 02:43

Gauravsa

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That satisfied me, Thank you for your further, clear and brief explanation. This will help me in future problems – Richard Mark Bonifacio Nov 09 '18 at 03:04
In the original code that the OP used, do the think the `Contains` call was `String.Contains` or `Enumerable.Contains`? _`Any` only makes sense discussing if the OP's code was using the latter - but I am almost certain it was using the former._ – mjwills Nov 09 '18 at 03:17

LINQ Return null even if it meets condtion

1 Answers1