{
	"@odata.context": "http://portal.xpertdoc.com/odata4/v6/$metadata#DocumentOutputPostActions/$entity",
	"DocumentOutputPostActionId": "00000000-0000-0000-0000-000000000000",
	"TemplateLibraryId": "00000000-0000-0000-0000-000000000000",
	"Name": "DOPA Name",
	"Description": null,
	"Metadata": "<DocumentOutputPostActionMetadata />",
	"CreatedByUserProfileId": "00000000-0000-0000-0000-000000000000",
	"CreatedDate": "2016-01-01T00:00:00.0000000Z",
	"ModifiedByUserProfileId": "00000000-0000-0000-0000-000000000000",
	"ModifiedDate": "2016-01-01T00:00:00.0000000Z",
	"Timestamp": "AAAAAAAAVXc="
}

var dopa = portalContext.DocumentOutputPostActions.Where(d => d.DocumentOutputPostActionId == Guid.Parse("00000000-0000-0000-0000-000000000000")).FirstOrDefault();	

dopa.Name = "New Name";
dopa.ValueToChange = value;

portalContext.UpdateObject(dopa);
portalContext.SaveChanges();