private IEnumerable GetRelatives(IEnumerable <IIdentifiable> source, RelativesExpression relativesExpression, Type itemType, DateTime asOf)
{
var results = Activator
.CreateInstance(typeof(List <>)
.MakeGenericType(itemType))
as IList;
var ids = source.Select(item => item.Id);
if (!ids.Any())
{
return(results);
}
var workItemLinks = WorkItemStore.QueryLinks(GetQueryStringForRelativesOf(ids, relativesExpression.AncestorType, relativesExpression.DescendentType, relativesExpression.Direction, asOf));
var map = new Dictionary <int, List <int> >();
workItemLinks.Where(link => link.SourceId == 0).ToList().ForEach(link => map.Add(link.TargetId, new List <int>()));
foreach (var ancestorId in map.Keys)
{
map[ancestorId].AddRange(GetTransitiveLinks(ancestorId, workItemLinks).Select(child => child.TargetId));
}
ids = ids.Union(workItemLinks.Select(link => link.SourceId)).Union(workItemLinks.Select(link => link.TargetId)).Where(id => id != 0);
var workItems = HydrateAndFilterItems(ids, relativesExpression.AncestorType, relativesExpression.DescendentType, asOf);
foreach (var ancestorId in map.Keys)
{
var id = ancestorId;
// Get the ancestor from the list of hydrated work items
var ancestorWorkItem = workItems.Single(item => item.Id == ancestorId);
// Filter the work items to just those IDs that are in the map for this ancestor.
// NOTE: Please note that the strategy is to start with the hydrated work items and filter to
// those in the map, and NOT to lookup every work item in the map. The latter strategy would
// break because the map also contains the IDs of Task Groups that have been filtered out.
// This way we start with work items that we already know exist.
var descendentWorkItems = workItems.Where(wi => map[id].Contains(wi.Id));
var ancestor = WorkItemMapper.Create(relativesExpression.AncestorType, new[] { ancestorWorkItem }).Cast <object>().Single();
var descendents = WorkItemMapper.Create(relativesExpression.DescendentType, descendentWorkItems);
var properTypedDescendents = GenerateListOfType(descendents, itemType);
var result = Activator.CreateInstance(itemType, ancestor, properTypedDescendents);
results.Add(result);
}
return(results);
}