Simple Provider Consumer Visual Webparts

Because of a question on http://sharepoint.stackexchange.com/questions/14325/created-connectable-webparts-but-the-connections-menu-item-is-not-showing I decided to create a provider consumer webpart in his most simple form.   

Create an empty SharePoint project in Visual studio.
Add two Visual WebParts:   

1. ProviderVisualWebpart
2. ConsumerVisualWebpart

In this most simple form of a provider consumer webpart only one string is passed from the provider to the consumer and it displayed in a Label control on the consumer webpart.   

Code in ProviderVisualWebpart.cs:   

public class ProviderVisualWebPart : System.Web.UI.WebControls.WebParts.WebPart, ITransformableFilterValues
{
    private const string _ascxPath = @"~/_CONTROLTEMPLATES/ConsumerProviderVWP/ProviderVisualWebPart/ProviderVisualWebPartUserControl.ascx";
 

    protected override void CreateChildControls()
    {
        Control control = Page.LoadControl(_ascxPath);
        Controls.Add(control);
    }


    public string ParameterName
    {
        get
        {
            return "Letter";
        }
    }


    public ReadOnlyCollection<string> ParameterValues
    {
        get
        {
            List<string> values = this.GetValues();
            return new ReadOnlyCollection<string>(values);
        }
    }


    private List<string> GetValues()
    {
        List<string> valueList = new List<string>();
        valueList.Add("A");
        return valueList;
    }


    [ConnectionProvider("Letter Filter", "ITransformableFilterValues")]
    public ITransformableFilterValues SetConnectionInterface()
    {
        return this;
    }


    public bool AllowEmptyValue
    {
        get { return true; }
    }


    public bool AllowMultipleValues
    {
        get { return false; }
    }


    public bool AllowAllValue
    {
        get { return true; }
    }
}

Code in ConsumerVisualWebpart.cs:   

public class ConsumerVisualWebPart : System.Web.UI.WebControls.WebParts.WebPart
{
    private const string _ascxPath = @"~/_CONTROLTEMPLATES/ConsumerProviderVWP/ConsumerVisualWebPart/ConsumerVisualWebPartUserControl.ascx";


    public ConsumerVisualWebPart()
    {
        _filterProviders = new List<IFilterValues>();
    }


    protected override void CreateChildControls()
    {
        ConsumerVisualWebPartUserControl control = (ConsumerVisualWebPartUserControl)Page.LoadControl(_ascxPath);
 

        control.ValueSendByProviderProperty = "From provider: ";
        foreach (IFilterValues filter in FilterProviders)
        {
            if (filter.ParameterValues != null)
            {
                foreach (string item in filter.ParameterValues)
                {
                    control.ValueSendByProviderProperty += item;
                }
            }
        }
 

        Controls.Add(control);
    }


    protected override void Render(HtmlTextWriter writer)
    {
        base.Render(writer);
        foreach (IFilterValues filter in FilterProviders)
        {
            writer.WriteLine(string.Format("Parameter: {0} <br>", filter.ParameterName));
        }
    }


    /// <summary>
    /// Hold incoming filtervalues
    /// </summary>
    private List<IFilterValues> _filterProviders;
    private List<IFilterValues> FilterProviders
    {
        get { return _filterProviders; }
    }


    [ConnectionConsumer("filter", "UniqueIDForConsumer", AllowsMultipleConnections = true)]
    public void SetFilter(IFilterValues filterValues)
    {
        if (filterValues != null)
        {
            List<ConsumerParameter> parameters = new List<ConsumerParameter>();
            parameters.Add(new ConsumerParameter("Letter", ConsumerParameterCapabilities.SupportsSingleValue | ConsumerParameterCapabilities.SupportsAllValue | ConsumerParameterCapabilities.SupportsEmptyValue));
            filterValues.SetConsumerParameters(new System.Collections.ObjectModel.ReadOnlyCollection<ConsumerParameter>(parameters));
            this.FilterProviders.Add(filterValues);
        }
    }
}

Code in ConsumerVisualWebpartUserControl.ascx.cs:   

public partial class ConsumerVisualWebPartUserControl : UserControl
{
    public string ValueSendByProviderProperty { get; set; }
 

    protected void Page_Load(object sender, EventArgs e)
    {
        ValueSendByProvider.Text = ValueSendByProviderProperty;
    }
}

Control added to VisualWebpart.ascx:   

<asp:Label ID="ValueSendByProvider" runat="server" Text="Label"></asp:Label>

That’s it!   

Put both controls on a page and connect them to each other.   

No connection set:   

 Connect:   

Configure:   

Connection established: