Get all values of a specific column of a specific content type

Question

I have a custom content type. In this content type, I have a text column (Mycolumn).

In a site collection, I have several instances of list bound to this content type.

Is there a way to retrieve all values of this column in all the site collection?

My goal is to build a webpart that suggest, in a drop down list, all existing value, in order to build a CAML query and display results.

I'm using SP2010 Standard, and a search server is setup (if it can helps).

Answer 1

The SPContentTypeUseage class may be of help to you here. It has a static method GetUsages(SPContentType) that will return a list of SPContentTypeUsage objects. Through those objects, you can determine the specific lists that use your content type, open the lists, and get all the values of your column.

Answer 2

Here is a possible solution to solve the problem:

    private IEnumerable<T> GetDistinctValues<T>(SPSite site, int listTemplateId, SPContentTypeId contentType, string fieldName)
    {
        var query = new SPSiteDataQuery
        {
            Lists = "<Lists ServerTemplate='" + listTemplateId + "' />",
            ViewFields = "<FieldRef Name='" + fieldName + "' Type='Text'/>",
            Query = "<Where><BeginsWith><FieldRef Name='ContentTypeId' /><Value Type='ContentTypeId'>" + SyndicateNewsContentTypeId + "</Value></BeginsWith></Where>" +
            "<OrderBy><FieldRef Name='" + fieldName + "' /></OrderBy>",
            Webs = "<Webs Scope='SiteCollection' />"
        };

        var result = site.RootWeb.GetSiteData(query);
        var resultView = new DataView(result);
        var distinct = resultView.ToTable(true, fieldName);

        foreach (DataRow item in distinct.Rows)
        {
            yield return (T)item[0];
        }
    }

Basically, the idea is to issue a SPSiteDataQuery that is filtering against my custom content type. Then, I use the DataView.ToTable method, to get distinct values.