Comments on: SharePoint Programmatically: Provisioning Lookup Fields

By: Marc Baye

Marc Baye — Tue, 15 Dec 2009 11:51:42 +0000

Pedro and Michhes are nearly right
Lookups can be provisioned in the schema.xml using the URL atribute of the list where it should be linked, using the "Lists/ListName" form, not only the "ListName".
Then, when you CREATE the instances using that list template, the lookup fiels will be linked correctly, but:
- Only those lookups that are declared in the schema when you create the list instance, future additions to the schema.xml will create new fields on the list instances but won't be correctly linked!
- The fields instantiated with this way won't upgrade if any change is made in its declaration in the original schema.xml. i.ex. if you change the format, the display name, or so on, in the schema.xml, other filds will change normally, but these lookups won't. (it's like they were customized, but without any versioning activated).

And… I tested it on the SharePoint 2010 beta, so… no good news

The programmatically way to link lookups will work always, of course, but will customize the fields too and they won't upgrade when the schema.xml changes.

By: Waldek Mastykarz

Waldek Mastykarz — Fri, 30 Oct 2009 06:28:10 +0000

@Kelly: You're welcome. Great I could help

By: Kelly Ford

Kelly Ford — Fri, 30 Oct 2009 02:35:00 +0000

Thanks so much for this bit of code. It has saved me loads of time.

By: Michhes

Michhes — Tue, 28 Jul 2009 05:45:35 +0000

Hopefully this pastes better

Fields.xml:

DisplayName="Indent Level"
Description=""
Group="My Cols"
ID="{05ba7786-ec2b-4d40-bf7c-7fb98d823e1f}"
****List="Indent Levels"*****
Name="MyLookup"
Required="TRUE"
ShowField="AgendaItemIndentLevel"
Type="Lookup"
UnlimitedLengthInDocumentLibrary="FALSE"
/>

Schema.xml:

DisplayName="Indent Level"
Description=""
Group="My Cols"
ID="{05ba7786-ec2b-4d40-bf7c-7fb98d823e1f}"
****List="Indent Levels"****
Name="MyLookup"
Required="TRUE"
ShowField="AgendaItemIndentLevel"
Type="Lookup"
UnlimitedLengthInDocumentLibrary="FALSE"
/>

By: Michhes

Michhes — Tue, 28 Jul 2009 05:43:55 +0000

Hi Waldek,

> Are you sure?

Yep, Pedro's right. You need to ensure the value supplied to the List attribute matches the List attribute on the field definition, otherwise the lookups won't populate (as per Josh's post at the above URL).

Fields.xml:

-Michhes

By: Waldek Mastykarz

Waldek Mastykarz — Sun, 21 Jun 2009 10:39:21 +0000

@Pedro Gomes: Are you sure? I just gave it yet another shot: although I was able to provision the field without any errors there was no connectivity to the Lookup List. Are you sure that you didn't use the cached version of the Field definition as described in comments here: http://blogs.msdn.com/joshuag/archive/2008/03/14/add-sharepoint-lookup-column-declaratively-through-caml-xml.aspx? I'm really curious in your approach.

By: Pedro Gomes

Pedro Gomes — Sun, 21 Jun 2009 09:21:48 +0000

That's not quite true. You can provision list lookup fields using only the Schema file.

The trick is that you can provide the list virtual path in the List attribute. Sharepoint will look for the list and get the ID for you

By: Waldek Mastykarz

Waldek Mastykarz — Fri, 13 Feb 2009 16:51:59 +0000

That's challenging indeed: because you add the lookup field programmatically, it's not in the Content Type while creating the schema.xml. I guess I'd go for programmatically attaching the Content Type to the list.

By: Raul Queiroga

Raul Queiroga — Fri, 13 Feb 2009 10:32:32 +0000

Great post, imagine now one wants to use that content type in a new list definition and that lookup column in one of the list's views. In the views part of the list schema.xml on has to repeat the content types fields, and in the lookup case it has to have the referenced list ID…having in mind one creates a solution package to aggregate all the features, how caw we set the schema.xml's lookup column referenced list ID with the ID of the recently created list?