asked on

Unable to cast object type 'Syatem.Int32' to type .System.String'.

Here, I am reading values from a table. Reading int type fields give me problem.

At line 14, I am getting error stating: "Unable to cast object type 'Syatem.Int32' to type .System.String'."

Question: How can I handle this.

Thank you.

public string ReadCriteria(string dataPoint)
    {
        string criteria = "";
        using (cn = SetConnection())
        {
            command.CommandText = "SELECT Top 1 [" + dataPoint + "] From RodCtiteria";
            command.CommandType = CommandType.Text;
            cn.Open();
            SqlDataReader reader = command.ExecuteReader();
            if (reader.HasRows)
            {
                reader.Read();
                if (!reader.IsDBNull(0)) // instead of: reader.GetString(0) != "" MetricIdL
                    criteria = reader.GetString(0);   //*********************< error here
            }
            reader.Close();
        }
        return criteria;
    }

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kaufmed

The data type of the data in the reader is of type int, so you cannot use GetString. You have to use the method that is appropriate for that data type: GetInt32.

e.g.

criteria = reader.GetInt32(0).ToString();

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Though you do want to ensure that you won't be getting nulls back from the database. If that be the case, then the logic will need to be tweaked.

Mike Eghtebas

ASKER

kaufmed,

Thank you for the solution. The values to be read are often string but sometimes int.

I suppose I need to add error handling here to handle both sting and int values to be read.

Question: If error handling is the way to go, could you please give me the syntax for it.

Later, I will learn about error handling to code it myself but at this point I could use some help.

If error handling is not necessary please add some comment on how would it work. I will try

criteria = reader.GetInt32(0).ToString();

to read both string and int values to see how it goes.

Regards,

Mike

Test Result:
Now I am getting "Specified cast is not valid." (in the case of string data of course).

It seems the following work, but the block is not complete.

try
                    {
                        criteria = reader.GetString(0);
                    }
                    catch
                    {
                   // }
                  //  finally
                   // {
                        criteria = reader.GetInt32(0).ToString();
                    }

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kaufmed

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Mike Eghtebas

ASKER

Thank you very much.