Object cannot be cast from DBNull to other types?

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4.00/5 (1 vote)

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hi am using dynamic in my project and am getting error which i mentioned above.

C#

if((Offset + BUFFER_LENGTH) >= System.Convert.ToInt32(LengthOutParam.Value))//this line am getting error

                   SizeParam.Value = System.Convert.ToInt32(LengthOutParam.Value) - Offset;
               else SizeParam.Value = BUFFER_LENGTH;

can any one suggest me.how to solve this error.??
thanks

Posted 4-Jun-12 20:30pm

ythisbug

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3 solutions

Solution 1

I assume that LengthOutParam is output parameter from database.

You are getting this error because in your sp this parameter hasn't been assigned a value.

And the default value is DBNull.

Posted 4-Jun-12 20:44pm

AhsanS

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Sandeep Mewara · Accepted Answer · 2012-06-04T20:46:00

Solution 2

Error as such is quite self explanatory. Still, if needed, a simple Google search[^] would have suggested you to check for the DBNULL validation before using it.

Try:

C#

if (LengthOutParam.Value != DBNull.Value)
{
   if((Offset + BUFFER_LENGTH) >= System.Convert.ToInt32(LengthOutParam.Value))
             SizeParam.Value = System.Convert.ToInt32(LengthOutParam.Value) - Offset;
   else SizeParam.Value = BUFFER_LENGTH;
}

Posted 4-Jun-12 20:46pm

Sandeep Mewara

Comments

VJ Reddy 5-Jun-12 3:34am

Good answer. 5!

Sandeep Mewara 5-Jun-12 4:39am

Thanks VJ.

Abhinav S 5-Jun-12 3:35am

My 5. My point exactly.

Sandeep Mewara 5-Jun-12 4:39am

Thanks Abhinav.

ythisbug 5-Jun-12 4:34am

thanks sandeep

Sandeep Mewara 5-Jun-12 4:39am

Welcome.

Espen Harlinn 5-Jun-12 8:13am

5'ed!

Sandeep Mewara 5-Jun-12 9:32am

Thanks.

Abhinav S · Accepted Answer · 2012-06-04T20:48:00

Solution 3

You are converting a DBnull type to an interger .
Simply check if Value is not DBNull and if not, convert to integer.

Example -

if((Offset + BUFFER_LENGTH) >= (LengthOutParam.Value == DbNull)?0:System.Convert.ToInt32(LengthOutParam.Value))

Posted 4-Jun-12 20:48pm

Abhinav S

Comments

VJ Reddy 5-Jun-12 3:34am

Good answer. 5!

Abhinav S 5-Jun-12 3:34am

Thanks VJ.

Sandeep Mewara 5-Jun-12 4:39am

Yep! 5.

Abhinav S 5-Jun-12 5:34am

Thank you Sandeep.

Espen Harlinn 5-Jun-12 8:13am

5'ed!

Abhinav S 5-Jun-12 8:30am

Thank you Espen.