Catch MSSQL stored procedure Output return value

[ce_nort]

Hello,
I've been banging my head against this for a while and can only seem to get a blank value returned. I have followed the advice in this thread and this documentation by binding a parameter to QSql::Out. I still seem to get a blank result, even though I know that is wrong as I can call the procedure with a result in SSMS. Am I constructing the query incorrectly? See relevant code below:

Stored procedure definition:

CREATE   procedure [dbo].[usp_SetGetNextRecordID] ( @TableName varchar(50), 
                                         @RecordID int OUTPUT )
as begin
  set nocount on
  update mt_Tables
  set LastRecordID = LastRecordID+1,
      @RecordID    = LastRecordID+1
  where TableName = @TableName
 
  return
end
GO

CREATE   procedure [dbo].[usp_SetGetNextRecordID] ( @TableName varchar(50), 
                                         @RecordID int OUTPUT )
as begin
  set nocount on
  update mt_Tables
  set LastRecordID = LastRecordID+1,
      @RecordID    = LastRecordID+1
  where TableName = @TableName

  return
end
GO

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Function definition for calling stored procedure:

QString DbController::runProcedureWithOutput(QString procedure_name, QMap<int, QString> values_list)
{
    QString return_value;
 
    QString query_string = QString("{CALL " + procedure_name + " (");
 
    QMapIterator<int, QString> i(values_list);
    while (i.hasNext()) {
        i.next();
        if (i.hasNext() == true) {
            query_string +=  "?,";
        } else {
            query_string += "?";
        }
    }
 
    query_string.append(")}");
 
    QSqlQuery query;
 
    query.prepare(query_string);
    query.setForwardOnly(true);
 
    int bound_out_value = 0; // Default
 
    //Bind values...
    QMapIterator<int, QString> j(values_list);
    while (j.hasNext()) {
     j.next();
     if (!j.hasNext()) {
         query.bindValue(j.key(), j.value(), QSql::Out); // Bind out value if last parameter
         bound_out_value = j.key();
     } else {
        query.bindValue(j.key(), j.value());
     }
    }
 
    query.exec();
 
    while(query.next()) {
        return_value = query.value(bound_out_value).toString();
    }
 
    return return_value;
}

QString DbController::runProcedureWithOutput(QString procedure_name, QMap<int, QString> values_list)
{
    QString return_value;

    QString query_string = QString("{CALL " + procedure_name + " (");

    QMapIterator<int, QString> i(values_list);
    while (i.hasNext()) {
        i.next();
        if (i.hasNext() == true) {
            query_string +=  "?,";
        } else {
            query_string += "?";
        }
    }

    query_string.append(")}");

    QSqlQuery query;

    query.prepare(query_string);
    query.setForwardOnly(true);

    int bound_out_value = 0; // Default

    //Bind values...
    QMapIterator<int, QString> j(values_list);
    while (j.hasNext()) {
     j.next();
     if (!j.hasNext()) {
         query.bindValue(j.key(), j.value(), QSql::Out); // Bind out value if last parameter
         bound_out_value = j.key();
     } else {
        query.bindValue(j.key(), j.value());
     }
    }

    query.exec();

    while(query.next()) {
        return_value = query.value(bound_out_value).toString();
    }

    return return_value;
}

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Usage of function:

QMap<int, QString> params;
params.insert(0, "table_name");
params.insert(1, "@RecordID");
 
QString result = db_controller->runProcedureWithOutput("usp_SetGetNextRecordID", params);
 
qDebug() << result; // Always empty string when it shouldn't be, no SQL Errors thrown.

QMap<int, QString> params;
params.insert(0, "table_name");
params.insert(1, "@RecordID");

QString result = db_controller->runProcedureWithOutput("usp_SetGetNextRecordID", params);

qDebug() << result; // Always empty string when it shouldn't be, no SQL Errors thrown.

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Any thoughts? Let me know if you need more context or have any questions. Help much appreciated in advance!