Working with the SharePoint Managed Metadata Column and Web Services

I was called into a client this morning to provide some development support around an application that a couple inhouse developers were working on that was attempting to make modifications to a Managed Metadata column through the use of web services. Particularly, the client was using the copy.asmx web service to attempt to set the values. They had already tried several permutations of values formats, and none of them had any effect on updating the data. Just a bunch of blank nonsense.

When attempting to work with the Managed Metadata column there are some important points to consider.

  1. The FieldInformation Type value will return a value of MultiChoice, but this is not the case. It’s actually Note.
  2. The field display name isn’t DisplayName, its DisplayName_0.
  3. The value to provide should be of form: [wssid];#[term name]|[term guid]

For the last point, providing a value for wssid is optional but the existence check for the particular term targeting your element is not.