LINQ to SharePoint and Document Sets

LINQ to SharePoint offers a great alternative to working directly with CAML queries in your SharePoint applications. Documents Sets are a convenient way to allow users to group a set of files together.  One of the challenges I recently had was figuring out how to deal with Document Sets within my LINQ queries. To follow these samples, you’ll want to start by creating a new document library (mine is called Resources) and enabling the Document Set content type on the library.

The first step is to ensure that the “Document Sets” feature is enabled on the Site Collection:

Next, create the library (or choose an existing one) and go to the advanced settings. From the advanced settings, set “Allow management of content types?” to “Yes”:

Clicking OK will bring you back to the library settings where you can select “Add from existing site content types” in the Content Types section. Add the “Document Set” content type and click “OK.”

With the document library setup, we’re ready to run SPMetal to generate the entity classes that will be used by LINQ. SPMetal is run from the command line and is located in the {SharePoint Root}\bin folder:

If you;re following along, you should now have a Content.cs file that can be brought into a Visual Studio project.

With all the plumbing done, it’s time to write some code. Let’s start by retrieving a document set based on the title:

public ResourcesDocumentSet GetDocumentSet(string title)
{
     using (Microsoft.SharePoint.Linq.DataContext ctx = new Microsoft.SharePoint.Linq.DataContext(_webUrl))
     {
         EntityList<ResourcesDocumentSet> resources = ctx.GetList<ResourcesDocumentSet>("Resources");
         ResourcesDocumentSet docSet = (from documentset in resources where documentset.Name == title select documentset).First<ResourcesDocumentSet>();
         return docSet;
     }

}

The first step is to create a DataContext and pass in the URL of the site we want to query. ResourceDocumentSet is an entity class that was generated by SPMetal. Remember that Resource was the name of the document library, thus ResourceDocumentSet is one of the entity classes generated. If you look into the generated code, the inheritance chain looks like this: ResourceDocumentSet –> DocumentSet –> DocumentCollectionFolder –> Folder –> Item. It is worth mentioning that in production, you would want to use FirstOrDefault instead of just first but the code demonstrates the concept.

If you examine the ResourceDocumentSet class, you’ll see that it exposes all the properties we would expect on a list item:

What it does not expose is any way to get at the documents inside of the Document Set. The trick here is that a Document Set is really just a wrapper around a Folder and a List Item. What we’re looking at above is basically the list item. In order to retrieve the contents of the Document Set, it is necessary to use the ScopeToFolder method:

public IQueryable<ResourcesDocument> GetDocumentsInSet(string setName)
{
     using (DataContext ctx = new DataContext(_webUrl))
     {
         DocumentSet docSet = GetDocumentSet(setName);

         EntityList<ResourcesDocument> documentList = ctx.GetList<ResourcesDocument>("Resources");
         var docSetItems = from documents in documentList.ScopeToFolder(docSet.Path + "/" + docSet.Name, true) select documents;

         return docSetItems;
     }
}

Building on the GetDocumentSet method we can then retrieve the contents (an EntityList of ResourceDocument) of the folder represented by the Document Set by limiting our scope to the URL of the document set (aka the folder). As you would expect, each ResourceDocument then exposes Title, Path, ID and other properties.

Hopefully, these examples will save you a little time in dealing with Document Sets and LINQ to SharePoint.