Question

I’m putting together a custom control flow SSIS task for the first time in C#. On my task UI editor I have a property grid and in one of the options I would like to be able to populate a drop down list of any task variables available as well as give the user the option of creating a new one. I’ve been researching for a few days and I have found some good examples on the forum but I’m a little lost now. My code as follows compiles and the editor displays a drop down list but its blank. After stepping through it, it appears to be down to this line:

taskHostProperty = context.Instance.GetType().GetProperty("TransferTask", typeof(TaskHost));The "TransferTask" being the name of my control flow task.  I'm wondering if this is correct?  

My full code for this is below.

//Property Grid Property
  [Category("General"),
            Description("Specifies the local Path for this task"),
            Browsable(true),
            ReadOnly(false),
            DesignOnly(false),
            TypeConverter(typeof(VariableConverter)),
            DisplayName("Local Path")]            
            public string LocalPath
            {
                get
                {
                    return this.stLocalPath;
                }
                set
                {                    
                    dtsVariableService = serviceProvider.GetService(typeof(IDtsVariableService)) as IDtsVariableService;
                    dtsVariableService.PromptAndCreateVariable(parentWindow, dtsContainer,"Local Path","User",typeof(string));
                    this.stLocalPath = value;
                }
            } 
//Variable Converter
internal class VariableConverter : TypeConverter
        {
            StandardValuesCollection svc = new StandardValuesCollection(new ArrayList());
            public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
            {
                return true;
            }
            public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
            {
                TaskHost taskHost = null;
                PropertyInfo taskHostProperty = null;
                List<string> values = new List<string>();
                values.Add(NEW_VARIABLE);
                if (context == null)
                {
                    return svc; 
                }
                if (context.Instance == null)
                {
                    return svc;
                }
                taskHostProperty = context.Instance.GetType().GetProperty("TransferTask", typeof(TaskHost));
                if (taskHostProperty == null)
                {
                    return svc;
                }
                taskHost = taskHostProperty.GetValue(context.Instance, null) as TaskHost;

                foreach(Variable v in taskHost.Variables)
                {
                    if (!v.SystemVariable && v.DataType == TypeCode.String)
                    {
                        values.Add(v.QualifiedName);
                    }
                }
                values.Sort();
                return new StandardValuesCollection(values);
    }

Answer 1

In the end I gave up trying to add the variables to a property grid and just created my own form. I used the following code to populate a combobox and after allowing the user to add a new SSIS variable. I refreshed the datasource. I would still like to know how to do this properly but I just didnt have the time to sit and work it out.
I used the following to first get the SSIS variables I needed, I’m able to add a new SSIS variable and I’m able to select the newly created one. I’m sure there is a better way of doing this but this works for now.

public ObservableCollection<string> FillVariableList()
        {
            ObservableCollection<string> variables = new ObservableCollection<string>();

            variables.Add(string.Empty);
            variables.Add(New_Variable);        

            foreach (Variable v in thetaskHost.Variables)
            {
                if (!v.SystemVariable && v.DataType == TypeCode.String && !variables.Contains(v.Name))
                {
                    variables.Add(v.Name);                  
                }
            }

            return variables;
        }

And I used the following to allow the user to add a new SSIS variable or select an existing SSIS variable and to refresh the SSIS variable combobox.

private void cmbxVariables_SelectionChangeCommitted(object sender, EventArgs e)
    {
        if (cmbxVariables.Text == New_Variable)
        {
            try
            {
                DtsContainer dtsContainer = null;
                dtsVariableServie = serviceProvider.GetService(typeof(IDtsVariableService)) as IDtsVariableService;
                Variable var = dtsVariableServie.PromptAndCreateVariable(null, dtsContainer, "VariableName", "User", typeof(string));
                if (!var.IsNull())
                {
                    cmbxVariables.DataSource = null;
                    cmbxVariables.DataSource = FillVariableList();
                }
            }
            catch (Exception exe)
            {
                MessageBox.Show(exe.ToString());
            }
        }
        else
        {
            foreach (Variable v in thetaskHost.Variables)
            {
                if (v.Name == cmbxVariables.Text)
                {
                    //Do something with the variable selected
                    break;
                }
            }
        }          
    }