Specified cast is not valid. in wpf c#?

Question

1.00/5 (2 votes)

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C#

int resourceType = row.Field<int>("jbd_jobno");

getting an error specified cast is not valid.

"jbd_jobno" is an integer

Please help me out

Posted 3-Nov-14 18:26pm

Satya Kumar Singha

Updated 3-Nov-14 18:40pm

DamithSL

v3

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Comments

[no name] 4-Nov-14 0:29am

What is row ? A dataRow ?

syed shanu 4-Nov-14 0:32am

you need to convert it into integer
int resourceType = Convert.ToInt32(row.Field("jbd_jobno"));

hope this will help you.

Sergey Alexandrovich Kryukov 4-Nov-14 0:52am

What is the actual column type?
For example, it could be "int?" (nullable), or something else.
—SA

2 solutions

Solution 2

Some clarification to Solution 1 (please see my comment to it):

Please look at the declaration of this extension method:
http://msdn.microsoft.com/en-us/library/bb360891%28v=vs.110%29.aspx[^].

For some data row and some column name, the method attempts to get the attribute value for this row. Even though this syntax itself is strongly typed, there is no such thing as miracle: the runtime type for the attribute may or may not be assignment-compatible with the actual generic parameter type you use (int, in this case). If it is not compatible, type cast is failed, throws exception you show. You need to use correct value type for this call, which is itself correct. Just find out what is the correct type expected.

—SA

Posted 3-Nov-14 18:59pm

Sergey Alexandrovich Kryukov

Updated 3-Nov-14 19:12pm

v2

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DamithSL · Accepted Answer · 2014-11-03T18:30:00

Solution 1

Please check SQL Server Data Type Mappings (ADO.NET)[^] and make sure you have selected correct type in c# for your database column type. If your column support null values you need to use nullable type as below

C#

int? resourceType = row.Field<int?>("jbd_jobno");

Posted 3-Nov-14 18:30pm

DamithSL

Updated 3-Nov-14 19:20pm

v5

Comments

[no name] 4-Nov-14 0:34am

Yes. Do it this way. because by default the table will be of object type. You will have to convert it this way

Sergey Alexandrovich Kryukov 4-Nov-14 1:12am

Let's be logical: if first line (as OP did, with int, not with "int?") throws exception, why would your second line work?
Yes, if required runtime type is int, it can always cast to "int?", but not visa versa, so, required type is not int.
Please see my answer which should clarify it.
—SA