LINQ: Cannot convert short to short?

Question

Cannot implicitly convert type 'short?' to 'short' at LocalAmount = t.EmpNo. I used Convert.ToInt16(t.EmpNo) but then the 'join' clause will get an error and be "incorrect", "type inference failed..."

    public class AccountTransaction
    {
        public Int16 LocalAmount { get; set; }
        public String AccountNumber { get; set; }
    }

    public static IEnumerable<AccountTransaction> GetAllTransactions()
    {
        using (var context = new SQL_TA_SCOREBOARDEntities1())
        {
            return (from t in context.EmployeeAccesses
                    join acc in context.View_HCM
                         on t.EmpNo equals acc.EmpNo
                    select new AccountTransaction
                    {
                        LocalAmount = t.EmpNo,
                        AccountNumber = acc.EmailAddress

                    }).ToList();
        }
    }

In your DB backend, what is presumably `EmployeeAccesses.EmpNo` is not explicitly `NOT NULL`. Consider changing `public Int16 LocalAmount` to `public Int16? LocalAmount`. — jdphenix, Mar 07 '14 at 06:22
Oh okay sorry everyone I didn't know anything about having NULLABLE issues. Now I understand. Thanks a lot! — Programming Dreamer, Mar 07 '14 at 06:30

score 2 · Accepted Answer · answered Mar 07 '14 at 06:19

2

Your error message states that t.EmpNo is a nullable Int 16. See the questionmark behind short?

'short?' to 'short' - Which says: I can not convert a Int16? to an Int16 The question mark defines, that this value can be null.

So if you change your model, you do not need to parse anything, but you need to use t.EmpNo.Value

public class AccountTransaction
{
    public Int16? LocalAmount { get; set; }
    public String AccountNumber { get; set; }
}

answered Mar 07 '14 at 06:19

Marco

22,856
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Wait sorry that was my second option, and I get the error in the 'join' with that. But if I remove the Convert.ToInt16, I get the cannot implicitly convert short to short. – Programming Dreamer Mar 07 '14 at 06:21
Okay thanks. Now I get that old "The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'join'." error. What do I do now? – Programming Dreamer Mar 07 '14 at 06:23

score 0 · Answer 2 · answered Mar 07 '14 at 06:50

0

It's likely that EmpNo should never be null, and that one of your EmpNo's is nullable in the database while the other is not. Make sure both are not nullable. If, for some reason they should be able to be Null sometimes, then they must both be nullable in the db. If this was happening and you fixed it in the db, you will have to reload your entity framework model and try your code again. You may need to change public Int16? LocalAmount { get; set; } back to public Int16 LocalAmount { get; set; }.

Essentially: Empno must be non nullable everywhere or nullable everywhere. In the database and the code.

answered Mar 07 '14 at 06:50

Chad McGrath

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Or use .GetValueOrDefault() to transition between Int16? and Int16 – SkeetJon Mar 07 '14 at 07:11
Thanks for the enlightenment! Now I'm beginning to grasp the concept, which I find hard from published sources. I'd vote up if I had enough reps. :( – Programming Dreamer Mar 07 '14 at 07:17

LINQ: Cannot convert short to short?

2 Answers2