LINQ to XML query from querystring

I need to create xml files based on querystring values.

My xml file:

<Products>
<Product>
    <Name>Name</Name>
    <Category>Books</Category>
    <SubCategory>Drama</SubCategory>
</Product>
<Product>
    <Name>Name</Name>
    <Category>Books</Category>
    <SubCategory>Action</SubCategory>
</Product>
<Product>
    <Name>Name</Name>
    <Category>Paper</Category>
    <SubCategory></SubCategory>
</Product>

So if i type ?filter=Books,Paper i need to select Product where Categorycontains value from querystring.

Then if i type ?filter=Books,Paper&filter2=Drama i still need 开发者_StackOverflowProduct where Category contains filter1 but if Product element containsSubCategory that containsfilter2 i need to select just those.

So with: ?filter=Books,Paper&filter2=Drama i need to get xml that looks like this:

<Products>
    <Product>
        <Name>Name</Name>
        <Category>Books</Category>
        <SubCategory>Drama</SubCategory>
    </Product>
    <Product>
        <Name>Name</Name>
        <Category>Paper</Category>
        <SubCategory></SubCategory>
    </Product>
</Products>

Also some products may have empty SubCategory element. I don't know if that is important.

My query looks like this:

var items = from el in SimpleStreamAxis(esysPath, "Product")
                        where filter.Contains(el.Element("Category").Value.Trim())
                        where filter1.Contains(el.Element("SubCategory").Value.Trim())
                        select new
                        {
                            ProductID = el.Element("ID").Value,
                            Name = el.Element("Name").Value,
                            Price = el.Element("Price").Value,
                            Picture = el.Element("Picture").Value
                        };

This is selecting all Product elements where filter1 contains SubCategory.

So can anyone point me in to right direction on how to write this query.

Thanks.

---

This should get you started in the right direction, it will find all products where the Category element is either Book or Paper

List<string> categories = new List<string() {"Book", "Paper"};
XDocument doc = XDocument.Parse("Your xml string");
var products = doc.Descendants("Product")
               .Where(el => categories.Contains(el.Element("Category").Value));