how to check for null in datarow row in c#

Question

I have this code

  foreach (DataRow row in DTgraph.Rows)
            {
                String UserName = row["UserName"].ToString();
                String LoggedState = row["LoggedState"].ToString();
                String InteractionId = row["InteractionId"].ToString();
                String InteractionType = row["InteractionType"].ToString();

            }

how to check if the row["something"] is null?

I tried to run the code, and the null values becomes "" (empty).

I need to check if these is null.

I now that this is an stupid question, but my problem is that I am making ToString() so i thought that null becomes null or NULL or Null or empty?

thanks

`DBNull.Value` will become an empty string. `null` will throw a `NullReferenceException` if you invoke `ToString()`. — Adriano Repetti, Apr 07 '14 at 15:38
And what you want to be your result if the value is null (well it's DBNull.Value) — Steve, Apr 07 '14 at 15:39
@user2226785 Perhaps it is not NULL after all, otherwise you will get an exception like Adriano mentioned. If you use `(string)xyz`, then you will get the behaviour you described (i.e. NULL becomes empty string with no exception thrown). — Racil Hilan, Apr 07 '14 at 15:39
@RacilHilan no it is NULL, I can see it from my eyes. really — user2226785, Apr 07 '14 at 15:40
Let me clarify: `NULL` (SQL) in your database won't be `null` (C#) in your record. `NULL` will be replaced with `DBNull.Value` in your C# code (but you'll still have `NULL` on your database). — Adriano Repetti, Apr 07 '14 at 15:40
@Adriano so I need to check this `if row["something"]==DBNull.Value` right? — user2226785, Apr 07 '14 at 15:41
@user2226785 You see it where? In the database? That doesn't mean it is null in your app. Place a break-point and see what values you're getting there. — Racil Hilan, Apr 07 '14 at 15:42
@RacilHilan I can't use breakpoist because I am deplyong on a server with no debugging environment — user2226785, Apr 07 '14 at 15:43
Thank you but no need to post another answer, feel free to accept huMpty's one! — Adriano Repetti, Apr 07 '14 at 15:44
possible duplicate of [How to get nullable DateTime out of the database](http://stackoverflow.com/questions/9503698/how-to-get-nullable-datetime-out-of-the-database) — Dour High Arch, Apr 07 '14 at 16:02

score 4 · Accepted Answer · edited Apr 07 '14 at 15:46

4

use DBNull.Value

 var UserName = row["UserName"].ToString();

to

 var UserName =  reader["UserName"] != DBNull.Value ? row["UserName"].ToString():"";

Update

 var UserName = "";
 if(reader["UserName"] != DBNull.Value)
 {
     UserName = row["UserName"].ToString();
 }

edited Apr 07 '14 at 15:46

pconnor88

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answered Apr 07 '14 at 15:41

huMpty duMpty

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kindly update your answer without the `?` i don't know how to use it :) – user2226785 Apr 07 '14 at 15:42
2

+1 to you, but someone answered me at the commetns. thanks a lot – user2226785 Apr 07 '14 at 15:42
@user2226785: I answered this on your previous question as well!! updated with if-else – huMpty duMpty Apr 07 '14 at 15:44
I will accept your answer after 5 minutes, the guy who answered me allowed me to do that. thanks for your efforts – user2226785 Apr 07 '14 at 15:46
The ?: operator is called conditional operator and acts like an if. so humptys statement translates to: string username; if(reader["UserName"] != DBNull.Value) { username = row["UserName"].ToString(); } else { username = string.Empty; } – xeraphim Apr 07 '14 at 15:47

how to check for null in datarow row in c#

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