title: Unable to determine the serialization information for *expression* using .Date
body: <p>I'm trying to read from a mongoDB collection with a Date filter (only the Date, time should be ignored):</p>
  
  <pre><code>var filterDefinition = Builders&lt;SomeClass&gt;.Filter.Eq(p =&gt; p.SomeDateTimeProperty.Date, DateTime.Now.Date);
  using (var cursor = await _someCollection.FindAsync(filterDefinition))
  { ... }
  </code></pre>
  
  <p><code>SomeClass</code> and the <code>SomeDateTimeProperty</code> property look like this:</p>
  
  <pre><code>[BsonIgnoreExtraElements]
  [Serializable]
  public class ReportConfiguration
  {
      ...
      public DateTime SomeDateTimeProperty { get; set; }
      ...
  }
  </code></pre>
  
  <p>The code throws an <code>InvalidOperationException</code> when trying to <code>.FindAsync()</code>:</p>
  
  <blockquote>
    <p>An exception of type 'System.InvalidOperationException' occurred in
    MongoDB.Driver.dll but was not handled in user code Additional
    information: Unable to determine the serialization information for p
    => p.SomeDateTimeProperty.Date</p>
  </blockquote>
  
  <p>Everything works if I remove the .Date part in the filter (p.SomeDateTimeProperty.Date, DateTime.Now.Date), but I need a yyyy\mm\dd comparison regardless of the hh\mm.</p>
  
  <p>Stacktrace says:</p>
  
  <pre><code>at MongoDB.Driver.ExpressionFieldDefinition`2.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry)
  at MongoDB.Driver.SimpleFilterDefinition`2.Render(IBsonSerializer`1 documentSerializer, IBsonSerializerRegistry serializerRegistry)
  at MongoDB.Driver.MongoCollectionImpl`1.CreateFindOperation[TProjection](FilterDefinition`1 filter, FindOptions`2 options)
  at MongoDB.Driver.MongoCollectionImpl`1.FindAsync[TProjection](FilterDefinition`1 filter, FindOptions`2 options, CancellationToken cancellationToken)
  at MongoDB.Driver.IMongoCollectionExtensions.FindAsync[TDocument](IMongoCollection`1 collection, FilterDefinition`1 filter, FindOptions`2 options, CancellationToken cancellationToken)
  at [...]
  </code></pre>
  
  <p>What could be the issue?</p>