In this article I like to show you my way to deploy lookup fields to SharePoint declarative. I need to note that I won’t do this fully declarative but found a solution that works best. This will be used by SharePoint internally and is fully supported. The lookups I’m talking are lookup fields deployed as site column.

Whenever it comes to content types and site column in my opinion the best way is to create them declarative. The reason for this is that I can handle that all deployed fields have the same GUID that I defined and every Site Collection has the same fields with the same IDs. Simple field types such as text, number, Date and Time, User Fields, Yes/No Fields can be created easily using the declarative approach but with lookup fields this can be a little bit trickier. During the last weeks I did a couple of interviews with Becky Bertram, Doug Hemminger and made a poll on SPYAM. The result of this was that most people deploy or create lookup fields using code and not using the declarative approach. Here is the result of the poll.

SPYam Poll for creating lookups

SPYam Poll on how creating lookups as web site columns

But now let’s take a look how to create a lookup field.

Creating the Lookup Field

The basic declaration of a lookup field looks simple and you can reference the List by using the URL of the web where the site column will be deployed to. This can be done according to the documentation as long as the list will be deployed in the same feature as the lookup column.

In a second module I created a basic list instance with a custom list.

Both elements will be deployed in the same feature which means that the reference of the lookup should match the list and replace the token List URL with the value for “Lists/Colors” with the GUID. The problem is that after the deployment the lookup column looks like this.

Lookup field after declarative deployment

Lookup field after declarative deployment

If you go to the definition of the lookup column the list is empty and won’t be displayed correctly and the field won’t work with lists. The empty “Get information from” is one reason that people create lookup fields using code. As always in SharePoint many ways lead to a solution and a lot of people have created their own provisioning classes to create site column lookup fields, but here comes the good news. This problem can be fixed some simple modifications of the field configuration using code.

Fixing declarative Lookup Field

From my experience the problem is that SharePoint won’t replace the List URL token with the GUID of the list and the web. When you like to use site columns as lookup fields than you have to get those GUID somehow to the schema of the fields. The URL token in Site columns cannot be used because site columns need to have a reference to the GUID of a list and a web. Then SharePoint will be able to find the matching list and web where the lookup should reference to. A sub site cannot make use of a list with the value “List/Colors”.

A quick solution would be to create the list first and the web first and add the GUID in the field definition. Works great as long as you don’t like to reuse the lookup field in another site collection. In this case you have to change the GUID when you like to deploy the solution to another web application or sites. Not really a great option.

My solution is to add the GUIDs to the schema of the field definition and use the List URL as a token to find the proper list. This can be done with a simple feature receiver. The code for this looks like this.

The code above does the following tasks:

  • Get the Field
  • Get the list that should be referenced by the lookup
  • Change SourceID and List to the GUID of the web and list.

Without using the feature event receiver the field looked this:

After the deployment with the feature event receiver the field looked like this:

SharePoint incremented the version number of the field after the changes have been applied to. The manipulation of the schema using the object model is fully supported by SharePoint but you need to take care that your modification are set with a proper xml that matches the field schema definitions. You will find this comment in the SPField.SchemaXML on the MSDN. There is not much difference in setting the schema of a field or create a field directly from XML using AddFieldAsXML.

A second look to the column settings shows that everything will be displayed correctly.

Lookup field after modified schema

Lookup field after modified schema using feature receiver

If you like to try this yourself you can download the solution N8D.Lookup.

Some other recommended Information on lookup fields I used previously was.

One of the new features in the SharePoint rich text editor is that now it is possible to embed external sources like Bing Maps, Vimeo videos, YouTube videos and other resources directly to the HTML content on an article page. In SharePoint 2010 html form web part or other special web parts needs to be used.

How it works

In the ribbon two buttons can be found to access the embedding feature. One can be found in the “Add audio and video” section the other is labeled with “Embed code”, both in the “Insert” group of the ribbon.

Embedding buttons in the ribbon

Embedding buttons in the ribbon

No matter which button will be used for embedding a YouTube, a modal dialog opens where the code for the embedding can be posted. Once the code has been added SharePoint provides a preview of the content that should be embedded.

Embedding dialog with preview

Embedding dialog with preview

After the submission the source will be added to the rich text editor as a so called “Snippet” that allows the position of the media or change the source of the embedded media.

Embedded sippet

Embedded sippet

As you see it’s now really easy to add external source to the content, but can be really embedded everything?

Embed everything or embed only allowed sources

Basically this new feature allows every iframe to be embedded, but allowing any iframe can lead to potentially scripting security problems. The good news here is that the allowed sources can be configured by a site collection administrator. The setting for this can be found in the site settings under site collection administration and is labeled as “HTML Field Security”. This offers the following configuration options:

  • Do not permit to add iframe from external external domain
  • Permit to add iframe from any external domain
  • Permit to add iframes from only the domains below
html field security settings

html field security settings

I think the last option is the most appropriate because it allows to manage what can be embedded. If something is missing from the list can be extended to support only trustful web sources.

Overall I think this is a great new feature for web content management and collaboration portals.