The data reader has more than one field error while calling a procedure that returns an integer

Question

I was trying to get status code of a stored procedure execution when encountered this error:

An exception of type 'System.Data.Entity.Core.EntityCommandExecutionException' occurred in EntityFramework.SqlServer.dll but was not handled in user code

Additional information: The data reader has more than one field. Multiple fields are not valid for EDM primitive or enumeration types.

I have rewritten the procedure to do absolutely nothing but to return an integer value, this is how it looks now:

ALTER Procedure [dbo].[test]
(
    @i int,
    @a nvarchar(max),
    @b nvarchar(max),
    @c nvarchar(max),
    @d nvarchar(max)
)
As
Begin
    SET NOCOUNT ON

    return 1
End

But I still get the same error at run-time when reaching the procedure call at line:

this.Database.SqlQuery<int>("test @i, @a, @b, @c, @d", p_i, p_a, p_b, p_c, p_d).FirstOrDefault();

Is there anyway to figure out what these fields are, and where they are coming from? And how should I get the returned value?

I've tried to specify a tuple of two strings as the T just to look into these values, but with no success...

Updates:
Select 1 instead of return 1 makes the function usable, the only question remains what are these mysterious fields that are returned to the data reader?

Solution

Database.SqlQuery<T>() expects some kind of result set (e.g. SELECT). Under the hood, it uses DbCommand.ExecuteReader(), and when T is scalar, it expects the result set to have exactly one field -- but if the result set has more than one field, or if there are no fields, it throws the exception that you encountered.

The return value can be retrieved by passing a DbParameter to Database.SqlQuery<T>() and setting Direction = ParameterDirection.ReturnValue as seen in these examples:

• How can I get return value of stored procedure when using SqlDataReader?
• http://blogs.msdn.com/b/diego/archive/2012/01/10/how-to-execute-stored-procedures-sqlquery-in-the-dbcontext-api.aspx

---

FYI, if you just want the return value, but you don't want a result set, use ExecuteSqlCommand with a DbParameter.

• EF6 stored procedure with no results

Comments

[Scharly Ochoa]

when are you getting that error on compile or runtime ? i think it should work. Also try "exec [dbo].[test] {0}, {1}, {2}, {3}, {4}"

[Jyrkka]

Have tried also the second one, the error remained the same, I'm getting it at runtime.

[Jyrkka]

Well, now the exception is different Error converting data type nvarchar to int.

[Ramesh Babu]

the statement is right. so check the datatype of the parameters within the stored procedure and the values you are passing to them.

[Jyrkka]

I can run the query from the SSMS, thus both the procedure and the values are usable. The only thing I can think of is that you need to put quotes around {1-4}, since @a, @b, @c and @d are nvarchars...

[Jyrkka]

Thank you for the explanation about the behind the scenes stuff, but I didn't get the point, the procedure returns exactly one value, I'm not sure that it can be thought of as a field though, but the message says that the reader has more than one field...

[jjj]

@Jyrkka: What I mean to say is that when using SqlQuery, it counts fields in the result set, so SELECT x, y, FROM table would have two fields. When T is a scalar, it expects one field, but if there are no fields, it looks like it gives the same error as when there are more than one.