Find an element in a collection of collection

How to use Linq to find an ite开发者_StackOverflow中文版m in a List of ProductCat where every ProductCat contains a List of Product.

I want to find the Product by ProductID.

Thanks

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Product foundProduct = productCatList
            .SelectMany(list => list.Products)
            .Where(product => product.ProductID == whateverID)
            .SingleOrDefault()

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Try this:

var results = from pc in myProductCats
              where pc.Products.Contains(ProductId)
              select pc;

You question is missing a lot of details. If you provide some code and the class structure I can provide a better answer.

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For a pure Linq language syntax:

  var pds = from pc in prodCats
            select from p in pc.Products where p.ProductID < 3
            select p;

But I think the IEnumerable extension + lambda version is more readable.