Presentation Details are shared across versions

Question

I've been wondering if anybody knows why the Presentation Details (stored in the Renderings field) are shared across all languages and versions by default?

I had confirmed this was the intended behaviour of 'shared' field with these links:

This SO post: In Sitecore, when adding a field to a template, there's a checkbox called "shared". What's it for?

And this SDN resource: http://sdn.sitecore.net/sdn5/reference/sitecore%205,-d-,3/field%20reference/field%20properties/data%20properties.aspx

The situation

As an author, I have created a new page and pushed it through workflow approval. Everything is great, and the page is published. The next day, I want to make some changes so I open up Page Editor, a new version is created, and I start adding and removing components on the page.

The problem

As soon as I hit save, the approved and published version of my page is also affected. The history of my previous layout is gone. As soon as a Site Publish is executed by somebody (or a scheduled PublishAgent executes) my page in the Web database will be updated.

Sure, the datasource of my new components that I added may not be published yet, but what if I added an existing datasource that was already approved? My removals also are immediate.

The desired goal

I'd like to be able to version these changes, and changing the field to no longer be shared seems like the right way to go. In my case, with a unilingual site, this won't impact the multilingual aspect of it.

Does anybody know why this field is shared across versions? If I unshare it, am I completely breaking the upgrade path?

Answer 1

I've just been "having a chat" with Sitecore support on this very issue. The concensus seems to be - paraphrasing what they said a bit - "We think it'll be fine if you change it. You should test it thoroughly, rendering deltas, page editor Work and so on".

I can add a few comments of my own; unchecking "shared" on __renderings, does appear to Work. At least at the initial glance. I've heard about this being done in solutions before and I've never heard any ill effects come from it.

And yet; whenever you mention it; you get a LOT of nervous responses and comments like "you really shouldn't be messing with Sitecore standard setup". And while a valid point indeed, I'd like to add a point of my own to this debate:

Given that, from an API perspective, there is very few things that are different when reading a field value from a "shared" field as opposed to a versioned one - I also believe there are very few potential cases where "unsharing" it would pose a problem.

Or in other words - I consider it low risk. But I've never had a real life solution running in a live environment either, with this setting changed :-)

I'm sorry, but I don't have a direct answer to your question - WHY Sitecore set it up like this, I belive to be part of Sitecore's heritage: The idea that multiple language versions of a site should be just "layered" versions of the exact same pages and therefore presentation details might as well be shared - presumably for some performance gain. I am not entirely convinced this vision still quite holds today - where editors daily "page edit up" new components on new versions, and set up special sale banners and related content weeks in advance.

Answer 2

I completely agree with and am thankful for the Mark Cassidy March 3 2014 answer to this. Since then, in Sitecore 8.0 they added "Versioned Layouts".

See:

https://dev.sitecore.net/en/Downloads/Sitecore%20Experience%20Platform/8%200/Sitecore%20Experience%20Platform%208%200/Release%20Notes "Versioned layouts – a different presentation set on different versions of different languages for the same item".

nice post: http://jockstothecore.com/sitecore-8-versioned-layouts-mixed-feelings/

Answer 3

This is the default behavior of sitecore as you mentioned in the post. Its not always good practice to change that. This topic has been dicussed earlier which might help you

Setting __Renderings field not shared in Sitecore consequences?

Answer 4

Here is a blog post about considerations for doing this:

Unsharing the Layout field in Sitecore - a multi-language strategy

That said, I've worked on a project where our client went in and did this themselves. It caused problems. As I recall, they unshared the __renderings field and all prior versions lost their presentation settings. Also, other languages other than the selected one also lost their settings. We had to do a DB restore and get things back and told them never to do that again. If you are considering this, read the blog post about, and do some isolated dry runs as it may expose issues you weren't aware of (e.g. impacting other languages, old versions, etc.).