Invalid cast reading data from table

Question

My Users table has a field called Admin which is tinyint(1). 1 for admin, 0 for normal user.

I want to set a session variable when users log in that is either true or false depending on if they're admin or not.

if ((int)Reader["Admin"] == 0)
{
    HttpContext.Current.Session["Admin"] = false;
}
else
{
    HttpContext.Current.Session["Admin"] = true;
}

Reader is a SqlDataReader. The code produces the following error:

System.InvalidCastException: Specified cast is not valid.

How can I properly cast Reader["Admin"] to an int?

score 3 · Accepted Answer · answered Nov 15 '12 at 05:54

3

That's because tinyint gets turned into a System.Byte which can't be explicitly cast to an System.Int32

answered Nov 15 '12 at 05:54

Josh

evanmcdonnal · Answer 2 · 2012-11-15T06:43:58.930

0

tinyint converts to Byte in C#. Change the cast/condtional to

 (Byte)Reader["Admin"] == 0

edited Nov 15 '12 at 06:43

answered Nov 15 '12 at 05:53

evanmcdonnal

isn't the right hand side is a int? and you are comparing a byte to an int? – शेखर Nov 15 '12 at 06:28
@krshekhar `Byte.minValue = 0` the integers from 0-255 are all valid `Byte` values. – evanmcdonnal Nov 15 '12 at 06:35
2

@krshekhar - It is relying on an Implicit cast. The code is valid. – Josh Nov 15 '12 at 06:38

score 0 · Answer 3 · edited May 23 '17 at 10:24

0

Check the below links

edited May 23 '17 at 10:24

Community

answered Nov 15 '12 at 06:13

Murali Murugesan

3 Answers3