Map Term Set To Site Column On SharePoint Using CSOM PowerShell

Now, we will see, how we can retrieve the term sets from the term store and assign it to the site column

The logic given below, retrieves the term set called "Test" from the taxonomy term store.

We got the term set. Now we will see how we can map it to site column called "Test".

1. From the context, get the root Web object. Afterwards, get the fields. From the field collection, get the respective field with the field name.
   
   1. $web = $ctx.Site.RootWeb
   2. $field = $web.Fields.GetByTitle("Test")
2. We need to cast the field object to taxonomy field by invoking the generic methods. For this, we will use MakeGenericMethod along with GetMethod. Here, we will use Taxonomy field object for casting the field object.
   
   1. $field = [Microsoft.SharePoint.Client.ClientContext].GetMethod("CastTo").MakeGenericMethod([Microsoft.SharePoint.Client.Taxonomy.TaxonomyField]).Invoke($ctx, $field)
3. Afterwards, we can assign the term set and store ID of the term set identified from the section, given above to the field by following the code snippet, given below:
   
   1. $field.SspId = $termStore.Id
   2. $field.TermSetId = $termSet.Id
4. Update the field, load the objects and execute the query to complete processing.
   
   1. $field.Update()
   2. $ctx.Load($web)
   3. $ctx.Load($field)
   4. $ctx.ExecuteQuery()

Here, we have mapped the term set to corresponding site column. The image, given below, shows the term set mapping to the site column.

The above set of the operations will help in mapping the term set of taxonomy to manage metadata site column. This will not affect the columns already created at the list level using the site column mentioned above. For updating the list level metadata columns with the same changes, we need to explicitly use an update operation, where it will push the changes from the site level to the list levels. Instead of giving $field.update() in the code, given above, we need to give $field.UpdateAndPushChanges($true). This will make changes available for list columns, already created.