Linq and EntityFramework 4 with multiple inner joins with nested subqueries

Question

I'm trying to write Linq query on this Products table based on FacetTypes that need to be grouped by their Facet.

This is the table structure:

I get passed an array of facetTypeIds, say 9, 6, 52

FacetTypeId 9 has a name of "160" and is a Facet of "Size"     
FacetTypeId 6 has a name of "157" and is a Facet of "Size"     
FacetTypeId 52 has a name of "Cool Brand" and is a Facet of "Brand" 

They need to be constructed into a query that joins based on the facet, like this:

select * from products p
inner join (select productId from productFacets where facetTypeId in (9, 6)) 
    p1 on p1.productId = p.productId
inner join (select productId from productFacets where facetTypeId in (52)) 
    p2 on p2.productId = p.productId

The outcome is a result set that says:

Get me Products which have brand "Cool Brand" and Sizes of (160 or 157)

How would I go about creating a linq query that will dynamically build this?

I'm kinda stuck as to how this would be formed in linq.

EDIT:

This is the code I've sort of come up with however it feels pretty inefficient.

MyDbContext _context;

// Groups FacetTypeIds by Facet into int lists 
Dictionary<int, List<int>> createFacetGroup(int[] facetTypeIds)
{
    var facets = new Dictionary<int, List<int>>();

    var facetTypes = from ft in _context.FacetTypes where facetTypeIds.Contains(ft.FacetTypeId) select ft;
    foreach (var facetType in facetTypes)
    {
        if (facets.ContainsKey(facetType.Facet.FacetId))
            facets[facetType.Facet.FacetId].Add(facetType.FacetTypeId);
        else
            facets.Add(facetType.Facet.FacetId, new List<int> { facetType.FacetTypeId });
    }

    return facets;
}

public List<Product> FindProductsByGroupedFacetTypeIds(int[] facetTypeIds)
{
    var groupedFacetTypeIds = createFacetGroup(facetTypeIds);

    // this seem very inefficient but ToList needs to be called 
    // otherwise the results products in the foreach loop dont end 
    // up with the correct result set
    var products = _context.Products.ToList(); 

    foreach (var facetTypeIdGroup in groupedFacetTypeIds)
    {
        var facetTypeIdGroupArray = facetTypeIdGroup.Value.ToArray();
        products = (from p in products where p.FacetTypes.Any(x => facetTypeIdGroupArray.Contains(x.FacetTypeId)) select p).ToList();
    }

    return products;
}

Answer 1

Try this If your entity model name is YourEntitie for example :

YourEntitie urEntity = new YourEntitie();
List<Products> prdList = (from pro in urEntity.Products.Include("FacetTypes")
                         where (pro.FacetTypes.Where
                                   (fac => fac.FacetTypeID == 9 ||
                                    fac => fac.FacetTypeID == 6).Count() > 0)
                               && (pro.FacetTypes.Where
                                         (fac => fac.FacetTypeID == 52).Count() > 0)
                         select pro).ToList();

Answer 2

In the interests of closing this question, i'll submit my solution for this.

It's not pretty but it works. If anyone else has a better solutions, I'd love to see it

MyDbContext _context;

// Groups FacetTypeIds by Facet into int lists 
Dictionary<int, List<int>> createFacetGroup(int[] facetTypeIds)
{
    var facets = new Dictionary<int, List<int>>();

    var facetTypes = from ft in _context.FacetTypes where facetTypeIds.Contains(ft.FacetTypeId) select ft;
    foreach (var facetType in facetTypes)
    {
        if (facets.ContainsKey(facetType.Facet.FacetId))
            facets[facetType.Facet.FacetId].Add(facetType.FacetTypeId);
        else
            facets.Add(facetType.Facet.FacetId, new List<int> { facetType.FacetTypeId });
    }

    return facets;
}

public List<Product> FindProductsByGroupedFacetTypeIds(int[] facetTypeIds)
{
    var groupedFacetTypeIds = createFacetGroup(facetTypeIds);

    // this seem very inefficient but ToList needs to be called 
    // otherwise the results products in the foreach loop dont end 
    // up with the correct result set
    var products = _context.Products.ToList(); 

    foreach (var facetTypeIdGroup in groupedFacetTypeIds)
    {
        var facetTypeIdGroupArray = facetTypeIdGroup.Value.ToArray();
        products = (from p in products where p.FacetTypes.Any(x => facetTypeIdGroupArray.Contains(x.FacetTypeId)) select p).ToList();
    }

    return products;
}