Finding a list item within a list item
<p>I'm a bit confused on how this works.</p>

<pre><code>class TestClass
{
    public int ID {get;set;}
    public List&lt;Stuff&gt; StuffList {get; set;}
}
class Stuff
{
    public int ID {get;set;}
    public string Description {get;set;}
}
</code></pre>

<p>So each <code>TestClass</code> has a list of <code>Stuff</code> in them.
What I want to do is find a <code>TestClass</code> that contains any <code>Stuff</code> with an <code>ID</code> of <code>0</code></p>

<pre><code>List&lt;TestClass&gt; TestList = RetrieveAllTestLists();
//Pseudocode:
//
// Find all TestClass in TestList that contain a Stuff with ID == 0;
</code></pre>

<p>I've tried this but it didn't work:</p>

<pre><code>List&lt;TestClass&gt; TestList = RetrieveAllTestLists().Where(x=&gt; x.StuffList.Where(y=&gt; y.ID == 0)).ToList();
</code></pre>

<p>Can anyone explain to me what I did wrong?</p>
