Nhibernate criteria API for many-to-many
My object model is the following:
Item has many Tags and a Tag could belong to many Items
I'd like to execute the following query using criteria's.
SELECT * FROM Item item
WHERE item.Id in (Select it.ItemId from dbo.ItemToTags it where it.Tag_id = 'ONE')
AND item.Id in (Select it.ItemId from dbo.ItemToTags it where it.Tag_id = 'TWO')
Meaning I would like to give a collection of possible tags and then provide all items that have all of these tags:
I tried the following but I get not results :
CreateCriteria<Item>().CreateAlias("Tags", "Tags");
if (AndQuery) {
foreach(var tag in Tags)
{
criteria.Add(Subqueries.PropertyEq("Tags.Id", DetachedCriteria.For<Tag>().A开发者_如何学编程dd(Restrictions.Eq("Id", tag)) .SetProjection(Projections.Property("Id"))));
}
}
I'm not sure if your query could be translated as :
SELECT * FROM Item item
join ItemToTags itt on itt.ItemId = item.Id
join Tags t on itt.TagId = t.Id
where t.Id in ('ONE','TWO')
If so, you should be able to do this :
CreateCriteria<Item>().CreateAlias('Tags','t')
.Add(Restrictions.In('t.Id',new List<string>{'TWO','ONE'}).List<Item>();
That's assuming you have the tags collection mapped on the Item.
hth
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