Controls are not inherited in winforms

Question

I have a function of return type datatable

public DataTable GetAllPrimaryKeyTables(string ConnectionString)
{ 
    // Create the datatable 
    DataTable dtListOfPrimaryKeyTables = new DataTable("tableNames");

    // Query to select primary key tables.
    string selectPrimaryKeyTables = @"SELECT 
                                           TABLE_NAME
                                          AS
                                           TABLES
                                        FROM 
                                           INFORMATION_SCHEMA.TABLE_CONSTRAINTS
                                       WHERE 
                                           CONSTRAINT_TYPE = 'PRIMARY KEY'
                                         AND
                                           TABLE_NAME <> 'dtProperties'
                                    ORDER BY
                                           TABLE_NAME";

    // put your SqlConnection and SqlCommand into using blocks! 
    using(SqlConnection sConnection = new SqlConnection(ConnectionString))
    using(SqlCommand sCommand = new SqlCommand(selectPrimaryKeyTables, sConnection))
    {
        try
        {
            // Create the dataadapter object 
            SqlDataAdapter sDataAdapter = new SqlDataAdapter(selectPrimaryKeyTables, sConnection);


            // Fill the datatable - no need to open the connection, the SqlDataAdapter will do that all by itself  
            // (and also close it again after it is done) 
            sDataAdapter.Fill(dtListOfPrimaryKeyTables);
            //using(StringWriter sw = new StringWriter())
            //{
            //    dtListOfPrimaryKeyTables.WriteXml(sw);
            //    sw.WriteLine();
            //    result = sw.ToString();
            //}
        }
        catch(Exception ex)
        {
            //All the exceptions are handled and written in the EventLog. 
            EventLog log = new EventLog("Application");
            log.Source = "MFDBAnalyser";
            log.WriteEntry(ex.Message);
        }
    }

    // return the data table to the caller 
    return dtListOfPrimaryKeyTables;
}

And I am calling it like this...

public class PrimaryKeyChecker : IMFDBAnalyserPlugin
{
    public DataTable RunAnalysis(string ConnectionString)
    {
        return GetAllPrimaryKeyTables(ConnectionString);
    }

In the IMFDBAnalyserPlugin I have

namespace MFDBAnalyser
{
    public interface IMFDBAnalyserPlugin
    {
        DataTable RunAnalysis(string ConnectionString);
    }

and on the main project background I have

private void btnStartAnalysis_Click(object sender, EventArgs e)
{
    SqlConnectionStringBuilder objConnectionString = new SqlConnectionStringBuilder();
    objConnectionString.DataSource = txtHost.Text;
    objConnectionString.UserID = txtUsername.Text;
    objConnectionString.Password = txtPassword.Text;
    string[] arrArgs = {objConnectionString.ConnectionString};

    string assemblyName = "PrimaryKeyChecker.dll";
    Assembly assembly = Assembly.LoadFrom(assemblyName);
    Type local_type = assembly.GetType("PrimaryKeyChecker.PrimaryKeyChecker");
    MethodInfo objMI = local_type.GetMethod("RunAnalysis");
    ConstructorInfo ci = local_type.GetConstructor(Type.EmptyTypes);
    object responder = ci.Invoke(null);
    object response = objMI.Invoke(responder, arrArgs);

But when I debug, the response object is returning only the empty datatable as I am unable to give the datasource in the first function because it is not inheriting controls there...

Hope the question is partially clear to you guys.. It should give the list of all tables when debugged but it is not taking the datagrid dgResultView there to give it a datasource...

Answer 1

This has nothing to do with inheritance; it looks like you are catching and logging exceptions:

    catch(Exception ex)
    {
        //All the exceptions are handled and written in the EventLog. 
        EventLog log = new EventLog("Application");
        log.Source = "MFDBAnalyser";
        log.WriteEntry(ex.Message);
    }

I would start by looking there; most likely something is throwing, and telling you why... If I had to guess, it looks like maybe you are missing:

sConnection.Open();

The fact that anything is returned tells me it is just an exception.

Personally I would have just let an unanticipated exception bubble to the UI, and let the UI react by logging it and showing the appropriate #fail page.

Also, when possible, cast the plugin to the interface:

string assemblyName = "PrimaryKeyChecker.dll";
Assembly assembly = Assembly.LoadFrom(assemblyName);
Type local_type = assembly.GetType("PrimaryKeyChecker.PrimaryKeyChecker");
IMFDBAnalyserPlugin analyser =
   (IMFDBAnalyserPlugin)Activator.CreateInstance(local_type);
DataTable response = analyser.RunAnalysis(objConnectionString.ConnectionString);