Sitecore 'dynamic placeholders' with MVC

Question

I'm looking for a working Dynamic Placeholder solution in MVC. There are at least two good descriptions of this "pattern" for use with WebForms:

• http://trueclarity.wordpress.com/2012/06/19/dynamic-placeholder-keys-in-sitecore/
• http://www.techphoria414.com/Blog/2011/August/Dynamic_Placeholder_Keys_Prototype

And I also found this blog explaining how to do it with MVC:

• http://blogs.perficient.com/portals/2012/10/17/sitecore-mvc-dynamic-placeholders/

First I have tried to implement Techphoria's method (with GUIDs) using techniques from the MVC blogpost (extension of the SitecoreHelper) and I also tried implementing the last described method (uses number suffixes that are incremented Column_1, Column_2, etc).

With all the variations I tried I didn't succeed in creating a working solution. My placeholders don't get properly named (I ended up with strange placeholder structures, or placeholders repeating themselves).

Without going into the specifics of my attempts, I would like to know if anyone else has a working solution ready that I could use.

If I can't find an already working solution, I will describe my problem in more detail and see if I can get that to work.

Answer 1

I created this extension that creates dynamic placholders

public static class SitecoreHelper
{
    public static HtmlString DynamicPlaceholder(this Sitecore.Mvc.Helpers.SitecoreHelper helper, string dynamicKey)
    {
        var currentRenderingId = RenderingContext.Current.Rendering.UniqueId;
        return helper.Placeholder(string.Format("{0}_{1}", dynamicKey, currentRenderingId));
    }
}

It creates a placeholder with the guid in the name. I also created a step in the pipeline that extracts the guid, and checks for placeholder settings.

Code to get placeholder settings to the dynamic placeholder If you create a dynamic placeholder with @Html.Sitecore().DynamicPlaceholder("test") - the following code takes the setting from the placeholder settings named test

 /// <summary>
/// Handles changing context to the references dynamic "master" renderings settings for inserting the allowed controls for the placeholder and making it editable
/// </summary>
public class GetDynamicKeyAllowedRenderings : GetAllowedRenderings
{
    //text that ends in a GUID
    private const string DYNAMIC_KEY_REGEX = @"(.+)_[\d\w]{8}\-([\d\w]{4}\-){3}[\d\w]{12}";

    public new void Process(GetPlaceholderRenderingsArgs args)
    {
        Assert.IsNotNull(args, "args");

        string placeholderKey = args.PlaceholderKey;
        Regex regex = new Regex(DYNAMIC_KEY_REGEX);
        Match match = regex.Match(placeholderKey);
        if (match.Success && match.Groups.Count > 0)
        {
            placeholderKey = match.Groups[1].Value;
        }
        else
        {
            return;
        }
        // Same as Sitecore.Pipelines.GetPlaceholderRenderings.GetAllowedRenderings but with fake placeholderKey
        Item placeholderItem = null;
        if (ID.IsNullOrEmpty(args.DeviceId))
        {
            placeholderItem = Client.Page.GetPlaceholderItem(placeholderKey, args.ContentDatabase,
                                                             args.LayoutDefinition);
        }
        else
        {
            using (new DeviceSwitcher(args.DeviceId, args.ContentDatabase))
            {
                placeholderItem = Client.Page.GetPlaceholderItem(placeholderKey, args.ContentDatabase,
                                                                 args.LayoutDefinition);
            }
        }
        List<Item> collection = null;
        if (placeholderItem != null)
        {
            bool flag;
            args.HasPlaceholderSettings = true;
            collection = this.GetRenderings(placeholderItem, out flag);
            if (flag)
            {
                args.CustomData["allowedControlsSpecified"] = true;
                args.Options.ShowTree = false;
            }
        }
        if (collection != null)
        {
            if (args.PlaceholderRenderings == null)
            {
                args.PlaceholderRenderings = new List<Item>();
            }
            args.PlaceholderRenderings.AddRange(collection);
        }
    }
}

The following code removes the guid from the chrome data in the pageeditor

/// <summary>
/// Replaces the Displayname of the Placeholder rendering with the dynamic "parent"
/// </summary>
public class GetDynamicPlaceholderChromeData : GetChromeDataProcessor
{
    //text that ends in a GUID
    private const string DYNAMIC_KEY_REGEX = @"(.+)_[\d\w]{8}\-([\d\w]{4}\-){3}[\d\w]{12}";

    public override void Process(GetChromeDataArgs args)
    {
        Assert.ArgumentNotNull(args, "args");
        Assert.IsNotNull(args.ChromeData, "Chrome Data");
        if ("placeholder".Equals(args.ChromeType, StringComparison.OrdinalIgnoreCase))
        {
            string argument = args.CustomData["placeHolderKey"] as string;

            string placeholderKey = argument;
            Regex regex = new Regex(DYNAMIC_KEY_REGEX);
            Match match = regex.Match(placeholderKey);
            if (match.Success && match.Groups.Count > 0)
            {
                // Is a Dynamic Placeholder
                placeholderKey = match.Groups[1].Value;
            }
            else
            {
                return;
            }

            // Handles replacing the displayname of the placeholder area to the master reference
            Item item = null;
            if (args.Item != null)
            {
                string layout = ChromeContext.GetLayout(args.Item);
                item = Sitecore.Client.Page.GetPlaceholderItem(placeholderKey, args.Item.Database, layout);
                if (item != null)
                {
                    args.ChromeData.DisplayName = item.DisplayName;
                }
                if ((item != null) && !string.IsNullOrEmpty(item.Appearance.ShortDescription))
                {
                    args.ChromeData.ExpandedDisplayName = item.Appearance.ShortDescription;
                }
            }
        }
    }
}

Edit

The web.config include settings are included below:

<sitecore>
  <pipelines>

    <getPlaceholderRenderings>
      <processor 
        type="YourNamespace.Pipelines.GetPlaceholderRenderings.GetDynamicKeyAllowedRenderings, YourAssembly"
        patch:before="processor[@type='Sitecore.Pipelines.GetPlaceholderRenderings.GetAllowedRenderings, Sitecore.Kernel']"/>
    </getPlaceholderRenderings>

    <getChromeData>
      <processor
        type="YourNamespace.Pipelines.GetChromeData.GetDynamicPlaceholderChromeData, YourAssembly"
        patch:after="processor[@type='Sitecore.Pipelines.GetChromeData.GetPlaceholderChromeData, Sitecore.Kernel']"/>
    </getChromeData>

  </pipelines>
</sitecore>