Question

Oracle column: user_id int not null,

Linq query:

UserId = user.Field<int>("user_id"),

UserId is int type. Other string, char fields are workign fine, only when I use thsi field I get this error.

What is the correct mapping or anythign I am doing wrong ?

Answer 1

If you’re using Field<T>() then that suggests you’re using a DataTable, at which point the database type is mostly irrelevant. The exception should show you how the cast has failed – what the actual type is. If it doesn’t, you can easily put some diagnostics in though:

object o = user["user_id"];
if (o == null)
{
    Console.WriteLine("user_id is null");
}
else
{
    Console.WriteLine("Actual type of user_id: {0}", o.GetType());
}

I suspect you’ll find it’s long or short, or something like that – but this should show you for sure.