Using the ALL operator in linq to filter child items of EntitySet

Question

I have a two objects as follows:

public class Item
{
    public int ItemId {get;set;}
    public string ItemName {get;set;}
    public List ItemTa         


        

Answer 1

That because you're puting the tags from the items to lowercase, but not the searched tags.

With this modification it should work:

List tagsList = tags
    .Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries)
    .Select(s => s.ToLower())
    .Distinct()
    .ToList();

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EDIT: OK, I see what the problem is: you're doing it backwards. You're searching for items that have only the tags that you're looking for.

Try that instead:

query = 
    (from item in query
     let itemTags = p.ItemTags.Select(it => it.TagName.ToLower())
     where tags.All(t => itemTags.Contains(t))
     select item).ToList();

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UPDATE: here's a version with the lambda syntax. It's pretty ugly because of the temporary anonymous type, but that's how the let clause translates to lambda...

query =
    query.Select(item => new { item, itemTags = item.ItemTags.Select(it => it.TagName.ToLower()) })
         .Where(x => tagsList.All(t => x.itemTags.Contains(t)))
         .Select(x => x.item)
         .ToList();