How to Work with Managed Metadata Columns by Using the SharePoint Client Object Model (Mia Kaushalendra Kumar)

Extracted from the original post

Managed metadata is a hierarchical collection of centrally managed terms that you can define and then use as attributes for items in Microsoft SharePoint Server 2010. Managed terms can act as sources of data for columns in libraries or lists. To manage the taxonomy column by using the server object model, there are APIs available under the Microsoft.SharePoint.Taxonomy namespace. However, handling managed metadata columns by using the client object model requires a different strategy.

Managed Metadata Columns

To work with managed metadata columns by using the SharePoint client object model, it helps to have an understanding of how managed metadata columns store values in lists. Consider the following details:

Managed Metadata Columns are derived from SPFieldLookup

TaxonomyFieldValue has a WSS identifier that is the Lookup ID property of the term in the TaxonomyHiddenList list. TheTaxonomyHiddenList list can be viewed by navigating to /Lists/TaxonomyHiddenList/AllItems.aspx. This list contains the details of all of the terms that are used in any managed metadata column.

For Each Managed Metadata Column, the List has Two Columns

For every metadata column, there are two columns in the list. One column is created with a field name of type Taxonomy Field and other column is created with the name in format fieldnameTaxHTField0 of type Note. Details of the taxonomy hidden column (fieldnameTaxHTField0) can be found in the XML of the taxonomy field. The XML of a taxonomy field is similar to the following. The Text Field highlighted in yellow contains the GUID of the hidden column.

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