Propagating Updates to Content Types

When you use a sitecollection contenttype on a list, what actually happens is a “copy” of the original contenttype is made and stored in the list. Thus, any changes to the original contenttype is not propagated into the list. As MS explains it:

“Do not, under any circumstances, update the content type definition file for a content type after you have installed and activated that content type. Windows SharePoint Services does not track all the changes made to the content type definition file. Therefore, you have no reliable method for pushing down all the changes made to site content types to the child content types.”

 

More on the topic can be read here:

http://soerennielsen.wordpress.com/2007/09/11/propagate-site-content-types-to-list-content-types/
http://msdn.microsoft.com/en-us/library/aa543504.aspx

A brief demonstration

My initial xml for the contenttype (and its fields), aka the feature, looks like this:

<Elements xmlns="http://schemas.microsoft.com/sharepoint">
  <ContentType
 ID="0x010008F15D6B2D0A454BA95AA5D91E21416E"
 Name="MyCustomContentType"
 Group="JL"
 Description="This is my custom content type">
    <FieldRefs>
      <FieldRef
        ID="{4e6a1cad-d0e4-4ce2-9086-8664cbb6ef73}"
        Name="CustomChoice" />
    </FieldRefs>
  </ContentType>
  <Field
 ID="{4e6a1cad-d0e4-4ce2-9086-8664cbb6ef73}"
 Name="CustomChoice"
 DisplayName="Custom Choice Column"
 Type="Choice"
 StaticName="CustomChoice"
 DisplaceOnUpgrade="TRUE"
 Group="JL">
    <CHOICES>
      <CHOICE>Choice 1</CHOICE>
      <CHOICE>Choice 2</CHOICE>
    </CHOICES>
  </Field>
</Elements>

 

 

Note: I have used this contenttype on a list that I call “My Custom List”.

I will now make a simple update to this contenttype like:

<CHOICES>
      <CHOICE>Choice 1</CHOICE>
      <CHOICE>Choice 2a</CHOICE>
      <CHOICE>Choice 3</CHOICE>
    </CHOICES>

If I look at the sitecollection contenttype the new values have been updated on the choice column:

 

Adding (or editing) an item in the list however still shows the old values:

OK, so how do we go around this issue?

The one place where I know the data is correct is the xml file containing the contenttype declaration, I´ll treat that as my “master”.

Adding a feature receiver to my contenttype feature will allow me to “pick up” that xml though the SPElementDefinition class.
The code looks like this, I´ll try to explain it at afterwards:

            SPSite sitecollection = properties.Feature.Parent as SPSite;
            using (SPWeb root = sitecollection.OpenWeb())
            {
 

                var query = from SPElementDefinition element in properties.Feature.Definition.GetElementDefinitions(CultureInfo.CurrentCulture)
                            where element.ElementType == "ContentType"
                            let xlmns = XNamespace.Get(element.XmlDefinition.NamespaceURI)
                            let ContentTypeXml = XElement.Parse(element.XmlDefinition.OuterXml)
                            let ContentTypeId = new SPContentTypeId(ContentTypeXml.Attribute("ID").Value)
                            from usage in SPContentTypeUsage.GetUsages(root.ContentTypes[ContentTypeId])
                            where usage.IsUrlToList == true
                            select new
                            {
                                UrlToList = usage.Url,
                                SiteColumns = (from fieldref in ContentTypeXml.Descendants(xlmns.GetName("FieldRef"))
                                               select root.Fields[new Guid(fieldref.Attribute("ID").Value)]).ToList()
                            };

                foreach (var result in query.ToList())
                {
                    using (SPWeb web = sitecollection.OpenWeb(result.UrlToList))
                    {
                        SPList list = web.GetList(result.UrlToList);

                        foreach (SPField fieldOnWeb in result.SiteColumns)
                        {
                            if (list.Fields.ContainsField(fieldOnWeb.InternalName))
                            {
                                SPField fieldInList = list.Fields[fieldOnWeb.Id];
                                fieldInList.SchemaXml = fieldOnWeb.SchemaXml;
                                fieldInList.Update();
                            }
                        }
                    }
                }
             }

 

So, what is happening here?

1. To start off with I´m using LINQ to first find the SPElementDefinitions of type contenttype.
2. Then I´m storing some values with the let parameter
   1. The xml definition of the SPElementDefinition (the actual xml in the file).
   2. The SPContentTypeId via the ID attribute of the xml stored in (a).
   3. The namespace
3. Then I fetch the SPContentTypeUsages where they point to being used in a list
4. I´m constructing an anonymous type containing the url to the list where the contenttype is being used together with all the SPFields from the sitecollection.
5. Finally loop through the findings in the query and open up the lists where the contenttype is used and update each fields xml with the one from the sitecollection.

 

And now, the contenttype is updated:

I know there are some limitations (stuff you can´t accomplish through this method) but at least it´s a start…