SharePoint Web Services - Updating ContentType field Required property?

Question

I've been trying to programmatically reproduce the behavior of editing a Content Type's field properties in the SharePoint site management screen and selecting the "Required" radio button with no sucess using the WSS 3.0 web service's Webs.asmx "UpdateContentType" method.

The first difficulty was the issue with the MSDN documentation that said fields should be of a FieldRef type when in fact they need to be of a Field type (reference). Adding fields and deleting fields works fine after the fix, but updating fields seems to not function at all. (It should also be noted that I followed the recommendation on the previous link to use Method="2" for updating fields but it changes nothing, and using Method values other than 1 for adding or other than 3 for deleting also function correctly).

Here's the web service call (slightly modified with strings instead of XmlNode objects for readability):

SharePointWebServices.Webs webService = new SharePointWebServices.Webs();
webService.Url = "http://mysharepointserver/site";
webService.UseDefaultCredentials = true;

webService.UpdateContentType(
    @"0x01005A089D9EC8A382458FB1F6C72096D52A", 
    @"<ContentType />", 
    @"<Fields />",
    @"<Fields><Method ID=""1""><Field Name=""SomeField"" ID=""{8a4803c4-6545-4a7a-804d-237eebff0ce3}"" Required=""TRUE"" Hidden=""FALSE"" ReadOnly=""FALSE"" PITarget="""" PIAttribute="""" PrimaryPIAttribute="""" Aggregation="""" Node="""" /></Method></Fields>",
    @"<Fields />");

After the call, the field is still Required="FALSE".

A quick look into the stssoap.dll assembly indicates that the "Required" property is apparently ignored during the update process. Is this normal behavior? If so, what is the recommended method for programmatically changing the "Required" field from client code (not executing on the SharePoint server)?

Any help would be greatly appreciated.

Answer 1

I've investigated this and found the same thing. I also tried adding the attribute Cmd="Update" to the Method element without success. This example of how to use UpdateContentType was helpful too.

I don't believe you will be able to do this with the out-of-the-box SharePoint services. You've verified from looking at stssoap.dll that this doesn't appear to work correctly. Another 'client'-style option is to use RPC methods but none appear to provide functionality for content types at all.

The web services are particularly frustrating because this type of not-so-edge case regularly comes up. It is very rare that I consider using them because of the time wasting involved with their limitations.

Do you have any option of deploying custom code to the server? You could develop this functionality using the object model and wrap it in your own custom web service (there is a walkthrough here) quite easily.

Here is an example adapted from Gabe Wishnie that does what you require:

SPContentType myContentType = myWeb.ContentTypes["myContentType"];
string internalName = myContentType.Fields["fieldToUpdate"].InternalName;
myContentType.FieldLinks[internalName].Required = false;
myContentType.Update(true);

Sorry this isn't more helpful but it's a common story when using the WSS 3.0 / SharePoint 2007 web services.