Issue trying to use Datasource Template in Sitecore sublayout; getting empty Sublayout.Datasource

Question

We've been trying to "componentize" our Sitecore solution as we move forward, in prep for transitioning to Page Editor usage (Woot! Finally!), but we're still practically working primarily with Page templates that may be inheritance-based composites of page specific fields, plus 1:many of these componentized templates. An example of how this looks in our solution is below -- Banner Feature Carousel and Featured Cartoon are some of these new components we're creating:

In the interest of trying to move away from using Sitecore.Context.Item (as I was recently reminded by this post) I've started filling in the Datasource template field on the sublayouts for the new components, and it seems like I've got the appropriate connections made between presentation details, the Sitecore sublayout and the .NET code file (as far as I can tell; again, we're newer to working this way).

I've also tried setting up a base class for these components as per this post by Nick Allen, but here's where I'm running into a problem: When I execute my code, this base class is finding the component Sublayout appropriately (the whole "this.Parent as Sublayout" thing) but, when I go to interrogate the Sublayout.Datasource property, it's an empty string. Here's my code (so far) for this base class:

public class ComponentBase : System.Web.UI.UserControl
{
    private Sublayout Sublayout { get { return Parent as Sublayout; } }

    public Item DataSourceItem 
    { 
        get 
        { 
            return Sublayout != null && !String.IsNullOrEmpty(Sublayout.DataSource) ? 
            Sitecore.Context.Database.GetItem(Sublayout.DataSource) : Sitecore.Context.Item; 
        } 
    }
}

I'm apparently missing some interplay between the Datasource Template field in the Sitecore sublayout, and how that actually translates to a datasource. Is it because these component templates are being used to compose Page templates? I was thinking that the datasource would just ultimately resolve to the Page template on which the component in question was currently being used, but perhaps that's my misunderstanding.

If anyone could give me any hints of things to check or point me to any resources I might use to get further, I'd appreciate it. I've done quite a bit of asking the Googs, myself, but am just not getting anything that's helping.

Thank you in advance, Sitecore friends!

Answer 1

It looks like you have configured the allowed templates for your sublayout in the steps you describe above. This basically tells Sitecore; 'allow user to select items based on these templates for this sublayout'. This alone does not set up the data source on items using the sublayout. You still need to go into the presentation details for any items using this sublayout, select the sublayout and then set its datasource property (within the content editor go to Presentation > Details > [Sublayout] > Data Source).

My answer to this question gives the source code needed to retrieve the datasource item and to iterate through the sitecore controls on your sublayout setting all of their Item propertys.

Here is the code:

public class SublayoutBase : UserControl
{
    private Item _dataSource;

    public Item DataSource
    {
        get
        {
            if (_dataSource == null)
            {
                if (Parent is Sublayout)
                {
                    _dataSource =
                        Sitecore.Context.Database.GetItem(((Sublayout)Parent).DataSource);
                }
                if (_dataSource == null)
                {
                    _dataSource = Sitecore.Context.Item;
                }
            }
            return _dataSource;
        }
    }

    protected override void OnLoad(EventArgs e)
    {
        foreach (Control c in Controls)
        {
            SetFieldRenderers(DataSource, c);
        }
        base.OnLoad(e);
    }

    private void SetFieldRenderers(Item item, Control control)
    {
        if (item != null)
        {
            var ctrl = control as Sitecore.Web.UI.WebControl;
            if (ctrl != null && !string.IsNullOrEmpty(ctrl.DataSource))
            {
                //don't set the source item if the DataSource has already been set. 
                return;
            }
            if (control is FieldRenderer)
            {
                var fr = (FieldRenderer)control;
                fr.Item = item;
            }
            else if (control is Image)
            {
                var img = (Image)control;
                img.Item = item;
            }
            else if (control is Link)
            {
                var link = (Link)control;
                link.Item = item;
            }
            else if (control is Text)
            {
                var text = (Text)control;
                text.Item = item;
            }
            else
            {
                foreach (Control childControl in control.Controls)
                {
                    SetFieldRenderers(item, childControl);
                }
            }
        }
    }
}

Answer 2

If you are using Sitecore 7 update 1 you can actually now use the attributes. From the Release Notes:

To make it easier to get the data source for a sublayout from code-behind, the data source is now transferred to the sublayout control in a "sc_datasource" attribute. (320768)

To get the data source from code, simply refer to this.Attributes["sc_datasource"];

Answer 3

When you start using sublayouts on which you will set your datasource try to use the marketplace "Sublayout Parameter Helper". When you use the class they provide as base class and have set everything up right in your Sitecore Environment you will find yourself having a "this.DatasourceItem" -> which will contain your datasource Item, or the context Item if none is given.

http://marketplace.sitecore.net/en/Modules/Sub_Layout_Parameter_Helper.aspx

To find out more on how datasource works, try searching on http://sdn.sitecore.net. There is alot of documentation available that should get you in the right direction. Generally it will be enough to just add a datasource in the sublayout that you can access in your sublayout.

When you read a datasource from a sublayout all it will do is check if the datasource field on that sublayout is filled and will return you information regarding this datasource. So when you add a new component to a page using the page editor (for example a sublayout for a news article) and you have a datasource template defined and filled in during adding this components, you will see that when you check the presentation details on that page a sublyaout with a datasource has been added. The datasource will point to a folder in which you will find an item based on the datasource template you specified on your sublayout. You should also double check this, cause if no datasource is present on the added sublayout it will be obvious you can't access it from your code.