How do I query multiple IDs via the ContentSearchManager? - sitecore

Question

When I have an array of Sitecore IDs, for example TargetIDs from a MultilistField, how can I query the ContentSearchManager to return all the SearchResultItem objects?
I have tried the following which gives an "Only constant arguments is supported." error.
using (var s = Sitecore.ContentSearch.ContentSearchManager.GetIndex("sitecore_master_index").CreateSearchContext())
{
rpt.DataSource = s.GetQueryable<SearchResultItem>().Where(x => f.TargetIDs.Contains(x.ItemId));
rpt.DataBind();
}
I suppose I could build up the Linq query manually with multiple OR queries. Is there a way I can use Sitecore.ContentSearch.Utilities.LinqHelper to build the query for me?
Assuming I got this technique to work, is it worth using it for only, say, 10 items? I'm just starting my first Sitecore 7 project and I have it in mind that I want to use the index as much as possible.
Finally, does the Page Editor support editing fields somehow with a SearchResultItem as the source?
Update 1
I wrote this function which utilises the predicate builder as dunston suggests. I don't know yet if this is actually worth using (instead of Items).
public static List<T> GetSearchResultItemsByIDs<T>(ID[] ids, bool mustHaveUrl = true)
where T : Sitecore.ContentSearch.SearchTypes.SearchResultItem, new()
{
Assert.IsNotNull(ids, "ids");
if (!ids.Any())
{
return new List<T>();
}
using (var s = Sitecore.ContentSearch.ContentSearchManager.GetIndex("sitecore_master_index").CreateSearchContext())
{
var predicate = PredicateBuilder.True<T>();
predicate = ids.Aggregate(predicate, (current, id) => current.Or(p => p.ItemId == id));
var results = s.GetQueryable<T>().Where(predicate).ToDictionary(x => x.ItemId);
var query = from id in ids
let item = results.ContainsKey(id) ? results[id] : null
where item != null && (!mustHaveUrl || item.Url != null)
select item;
return query.ToList();
}
}
It forces the results to be in the same order as supplied in the IDs array, which in my case is important. (If anybody knows a better way of doing this, would love to know).
It also, by default, ensures that the Item has a URL.
My main code then becomes:
var f = (Sitecore.Data.Fields.MultilistField) rootItem.Fields["Main navigation links"];
rpt.DataSource = ContentSearchHelper.GetSearchResultItemsByIDs<SearchResultItem>(f.TargetIDs);
rpt.DataBind();
I'm still curious how the Page Editor copes with SearchResultItem or POCOs in general (my second question), am going to continue researching that now.
Thanks for reading,
Steve

Answer 1

You need to use the predicate builder to create multiple OR queries, or AND queries.
The code below should work.
using (var s = Sitecore.ContentSearch.ContentSearchManager.GetIndex("sitecore_master_index").CreateSearchContext())
{
var predicate = PredicateBuilder.True<SearchResultItem>();
foreach (var targetId in f.Targetids)
{
var tempTargetId = targetId;
predicate = predicate.Or(x => x.ItemId == tempTargetId)
}
rpt.DataSource = s.GetQueryable<SearchResultItem>().Where(predicate);
rpt.DataBind();
}