Passing datatable to SQL Server stored procedure not working - asp.net

Question

I have an ASP.NET application that passes a Datatable to a web service, then from the web service to a SQL Server stored procedure. When I publish the web application and web service to the server and run, it fails. When I run the application from the local host pointing to the web service on the server, it works fine. When I run the both the web application and web service from localhost, it works fine.
I did some troubleshooting and see that the following line is the problem but I am not sure how to solve:
cmdCommit.Parameters.AddWithValue(#SourceTable, dtSource);
When I comment the line above, everything works. When I replace the reference to the DataTable (dtSource) in the line above with a string datatype, it works.
Here is the entire web method, I am using this code within a try/catch block:
DataTable dtSource = ObjectToData(sourceTable);
dtSource.TableName = TableTypeObject;
using (SqlConnection cnn = new SqlConnection(_cnnSqlCapss))
{
SqlCommand cmdCommitChange = new SqlCommand("usp_Stored_Procedure", cnn);
cmdCommitChange.CommandType = CommandType.StoredProcedure;
cmdCommitChange.Parameters.AddWithValue("#Parm1", Value1);
cmdCommitChange.Parameters.AddWithValue("#Parm2", Value2);
cmdCommitChange.Parameters.AddWithValue("#Parm3", dtSource);
var returnParameter = cmdCommitChange .Parameters.Add("#ReturnVal", SqlDbType.Int);
returnParameter.Direction = ParameterDirection.ReturnValue;
cnn.Open();
cmdCommitChange .ExecuteNonQuery();
var result = returnParameter.Value;
return (int)result;
}
The confusing part is that when I run the web application from the localhost and reference the web service on the server, it works. I don't understand why it fails when I run the web application from the server.
When I comment the line that reference the DataTable everything works.
I have tried the following and still no success:
SqlParameter tvpParam cmdCommit.Parameters.AddWithValue "#SourceTable", dtSource);
tvpParam.SqlDbType = SqlDbType.Structured;
tvpParam.TypeName = "dbo.SourceTableType";
Also, The web method is not throwing an exception.

Answer 1

Assumed you're already doing these:
Defining table type in User-Defined Table Types in your database (often known as TVP, see reference section below);
Adding parameter to pass DataTable to stored procedure (e.g. #SourceTable).
Then, you can use SqlDbType.Structured to pass DataTable contents as stored procedure parameter like this:
cmdCommitChange.Parameters.Add("#SourceTable", SqlDbType.Structured).Value = dtSource;
Alternative with AddWithValue:
cmdCommitChange.Parameters.AddWithValue("#SourceTable", dtSource).SqlDbType = SqlDbType.Structured;
Example usage in SqlConnection block:
using (SqlConnection cnn = new SqlConnection(_cnnSqlCapss))
{
SqlCommand cmdCommitChange = new SqlCommand("usp_Stored_Procedure", cnn);
cmdCommitChange.CommandType = CommandType.StoredProcedure;
cmdCommitChange.Parameters.AddWithValue("#Parm1", Value1);
cmdCommitChange.Parameters.AddWithValue("#Parm2", Value2);
cmdCommitChange.Parameters.AddWithValue("#Parm3", Value3);
// add this line
cmdCommitChange.Parameters.Add("#SourceTable", SqlDbType.Structured).Value = dtSource;
cmdCommitChange.Parameters.Add("#ReturnVal", SqlDbType.Int).Direction = ParameterDirection.ReturnValue;
cnn.Open();
cmdCommitChange.ExecuteNonQuery();
var result = (int)returnParameter.Value;
return result;
}
Reference:
Table-Valued Parameters (MS Docs)

Answer 2

I found the problem. I am passing a text value that is too large for a column on my datatable.
The web service was indeed throwing an exception but there was some code in my application's routine which was preventing me from seeing it.