Would like to create a combobox property editor for a custom ativity

Question

I have tried searching all over for this solution and came across this thread which is close.

http://social.msdn.microsoft.com/Forums/en/wfprerelease/thread/a5b6982f-c7f2-49b3-a183-ddb0eb3075cc

However I do not want to put all of my properties on the custom activity since I will have about 8-10 of them that the person designing the workflow will be able to set and that will take up to much space on the workflow canvas.  The solution above provided a good solution that allows the combo box to be used to set a value directly in the activity.  Also I am rehosting the workflow designer so that our customers can build their workflows.  I have followed the pattern of using WPF that is shown in many posts out there where the property editor grid is on the right hand side. 

I would like to modify the property editors behavior to not use the expression editor and instead use a custom combobox to allow the user to pick from a list.   I have the followoing code in my activity with a seperate class that holds the custom property editor.   This is giving me the combo box in the property grid editor however I have no idea on how to populate the drop down with values.  

Here is the class for the custom editor:

  class DropDownEditor : PropertyValueEditor
  {
    public DropDownEditor()
    {
      this.InlineEditorTemplate = new DataTemplate();
      FrameworkElementFactory stack = new FrameworkElementFactory(typeof(StackPanel));
      FrameworkElementFactory dropDown = new FrameworkElementFactory(typeof(ComboBox));
      Binding dropDownBinding = new Binding("Value");
      dropDownBinding.Mode = BindingMode.TwoWay;

      stack.AppendChild(dropDown);

      this.InlineEditorTemplate.VisualTree = stack;
    }

  }

And here is the code for my custom activity:

  public sealed class WorkflowQueue : NativeActivity
  {
    // Define an activity input argument of type string
    public string SelectedForm { get; set; }
    public string SelectedQueue { get; set; }

    static WorkflowQueue()
    {
      //this section registers each field that needs to have a specific type of property editor. Like a drop down.
      AttributeTableBuilder builder = new AttributeTableBuilder();
      builder.AddCustomAttributes(typeof(WorkflowQueue), "SelectedForm", new EditorAttribute(typeof(DropDownEditor), typeof(PropertyValueEditor)));
      builder.AddCustomAttributes(typeof(WorkflowQueue), "SelectedQueue", new EditorAttribute(typeof(DropDownEditor), typeof(PropertyValueEditor)));
      MetadataStore.AddAttributeTable(builder.CreateTable());
    }

    // If your activity returns a value, derive from CodeActivity<TResult>
    // and return the value from the Execute method.
    protected override void Execute(NativeActivityContext context)
    {
      // Obtain the runtime value of the Text input argument
    }
  }

You can see that there is a SelectedFormProperty and a SelectedQueue property.  When I run my hosted designer and drop this custom activity onto the form I see the 2 input properties in the property editing grid as drop downs, just with no values.   So I am trying to figure out how to populate each of those with a list of options I will retrieve from the database.  Also I am hoping to be able to reuse the custom editor for all properties that need a combobox as the editing choice.

Any direction would be greatly appreciated.

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Thank you, Wade

Answer 1

Hi Wade,

One way is to define the template in XAML like below:

<DataTemplate x:Key="dropDownEditorTemplate">
  <ComboBox SelectedItem="{Binding Path=Value, Mode=TwoWay}">
    <ComboBox.Items>
    <s:String>Item1</s:String>
    <s:String>Item2</s:String>
    </ComboBox.Items>
  </ComboBox>
</DataTemplate>

and then assign this.InlineEditorTemplate to this DataTemplate in your DropDownEditor.

Thanks,
Tony 

Answer 2

How would you bind a custom datasource (DataTable) to this combo?

---

PaulM

Answer 3

How would you bind a custom datasource (DataTable) to this combo?

---

PaulM

Found a solution, if anyone is interested.

       public DropDownEditor()
        {
            try
            {

                this.InlineEditorTemplate = new DataTemplate();
                FrameworkElementFactory combo = new FrameworkElementFactory(typeof(ComboBox));
        
                Binding b = new Binding("Value");
                b.Mode = BindingMode.TwoWay;
                b.Converter = new StateConverter();                combo.SetValue(ComboBox.SelectedValueProperty, b);                                               
                Binding items = new Binding("options");
                items.Source = this; 
                combo.SetValue(ComboBox.ItemsSourceProperty, items);                combo.SetValue(ComboBox.SelectedValuePathProperty, "ID");
                DataTemplate itemTemplate = new DataTemplate();
                FrameworkElementFactory textBlock = new FrameworkElementFactory(typeof(TextBlock));
                Binding text = new Binding();
                text.Converter = new DataTableConverter();                textBlock.SetValue(TextBlock.TextProperty, text);
                itemTemplate.VisualTree = textBlock;                combo.SetValue(ComboBox.ItemTemplateProperty, itemTemplate);
                this.InlineEditorTemplate.VisualTree = combo;
            }

public DataTable options
        {
            get
            {
                DataTable lst = new DataTable();
                lst.Columns.Add("ID", typeof(string));
                lst.Columns.Add("TEXT", typeof(string));
                lst.Rows.Add(...)
...
}
}
public class StateConverter : IValueConverter
    {
        public StateConverter()
        {
            ;
        }
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {

            if (value != null)
            {
                Activity<string> expression = (value as InArgument<string>).Expression;
                VisualBasicValue<string> vbexpression = expression as VisualBasicValue<string>;
                Literal<string> literal = expression as Literal<string>;
                if (literal != null) { return literal.Value.ToString(); }
                else if (vbexpression != null) { return vbexpression.ExpressionText; }
            }
            return null;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value == null) return null;
            InArgument<string> inArgument = value.ToString();
            // Convert combo box value to InArgument<string>
            return inArgument;
        }
    }

   public class DataTableConverter : IValueConverter
    {
        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value != null && (value as System.Data.DataRowView) != null)
            {
                return (value as System.Data.DataRowView).Row["TEXT"].ToString();
            }
            return null;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }

        #endregion
    }

---

PaulM