Handle Nulls in foreach statement

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Please suggest me how to handle DBNUll values in foreach loop. Below is my code

C#

foreach (string  s in dr.Row.ItemArray)
{
    sb.Append(s);
    sb.Append("/t");
}

My item array have DBNull values. So I'm getting error.How to resolve this.

here at the time of getting value to string "s", I'm getting the error. not inside the loop...!

Posted 17-Nov-11 18:39pm

avi_dadi2002

Updated 17-Nov-11 21:36pm

Pandya Anil

v4

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Comments

LanFanNinja 18-Nov-11 0:55am

Check solution below.

Pandya Anil 18-Nov-11 3:38am

string is nullable type, you can assign null to it. it can not be error there, check once again :)

5 solutions

Solution 4

My Answer based on your Question details and comments in Solution-1.

Quote:
I can do the same what you suggested, If I'm able to enter inside the loop i can do like this but at the time of assigning value to string"s" I'm getting the error.

I doubt your Syntax is correct and event it is compiling without Error.

Have a look at below link for proper syntax of DataRow.ItemArray Property.

http://msdn.microsoft.com/en-us/library/system.data.datarow.itemarray.aspx

Property DataRow.ItemArray returns Array of object.

You may try by changing your code as below.

C#

DataRow dr = null;
StringBuilder sb = new StringBuilder();
//Assign some data to your dr here.
                
foreach (object o in dr.ItemArray)
{
  if (o != null && o != DBNull.Value)
  {
    sb.Append(Convert.ToString(o));
    sb.Append("/t");
  }
}

Posted 17-Nov-11 22:27pm

RaisKazi

Solution 3

I would do something like this

C#

foreach(object o in dr.Row.ItemArray)
{
    if(o!=DBNull)
    {
        sb.Append(o.ToString());
        sb.Append("/t");
    }
}

Your error is because there is no implicit conversion from DBNull to string. (I think!)

Posted 17-Nov-11 22:23pm

Paul E Davies

Solution 2

if you want to hadle only null

if(s != null))
{
sb.Append(s);
sb.Append("/t");
}

if you need to handle null and empty string

C#

if(!string.IsNullOrEmpty(s))
                {
                sb.Append(s);
                sb.Append("/t");
                }

but if you need to check ISDBNULL.. use this generic method.. or customize it in to your solution

C#

public static T GetDBValue<T>(SqlDataReader reader, string Column)
       {

           int _intColumnID = reader.GetOrdinal(Column);

           if (reader.IsDBNull(_intColumnID))
               return default(T);
           else
               return (T)reader.GetValue(_intColumnID);

       }

hope this will help...

Posted 17-Nov-11 18:58pm

dinidusoft123

Solution 5

C#

foreach (object o in dr.Row.ItemArray)
{
    if (o is string)
    {
        sb.Append(o.ToString());
        sb.Append("/t");
    }
}

Posted 30-Nov-11 8:54am

Member 2315574

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LanFanNinja · Accepted Answer · 2011-11-17T18:53:00

Solution 1

Well I don't mess with databases too much but something like this may help

C#

foreach (string s in dr.Row.ItemArray)
{
    if (s != System.DBNull.Value)
    {
        sb.Append(s);
        sb.Append("/t");
    }
}

Posted 17-Nov-11 18:53pm

LanFanNinja

Updated 17-Nov-11 18:54pm

v2

Comments

Sergey Alexandrovich Kryukov 18-Nov-11 1:30am

Well, I don't mess with databases too much but I'm pretty much sure it's correct as I recently did something like that; my 5. :-)
--SA

LanFanNinja 18-Nov-11 1:34am

Thank you

avi_dadi2002 18-Nov-11 3:35am

Thanks for your answer, I can do the same what you suggested, If I'm able to enter inside the loop i can do like this but at the time of assigning value to string"s" I'm getting the error.

LanFanNinja 18-Nov-11 8:50am

Maybe use a for loop instead. i.e.
for (int i = 0; i < dr.Row.ItemArray.Length; i++)
{
if (dr.Row.ItemArray[i] != System.DBNull.Value)
{
}
}