How to add renderings programmatically when another rendering is added

Question

Which pipeline should I use when a new rendering is added in the presentation?

I have a scenario to add renderings programmatically if a particular rendering is added in the item. I will write a custom method to compare if the added rendering's template Id matches the required template ID then it will add renderings programmatically. I have a logic in mind but not sure which pipeline to use.

Answer 1

It's not a pipeline, but you could use the item:saved event's event args' ItemChanges property for this.

Basically, you would:

1. Check to see if the item saved was of the template you are looking for

   var savedItem = Event.ExtractParameter(args, 0) as Item;
   if (savedItem == null || savedItem.TemplateID != new ID("YOUR-TEMPLATE-ID"))
     return;
   

2. Check to see if one of the Sitecore.Data.Items.ItemChanges was the Sitecore.FieldIDs.LayoutField or Sitecore.FieldIDs.FinalLayoutField

   var itemChanges = Event.ExtractParameter(args, 1) as ItemChanges;
   if (itemChanges == null || !itemChanges.HasFieldsChanged || (!itemChanges.IsFieldModified(FieldIDs.LayoutField) && !itemChanges.IsFieldModified(FieldIDs.FinalLayoutField)))
     return;
   

3. Check to see if the difference between the two includes adding the rendering you care about

4. Add your other renderings

Note that this will fire every time anything is saved in Sitecore (including the changes you make at step 4 above!), so make sure you put in checks early to get out if your code isn't going to apply.