title: WPF ICollectionView Filter Reset
body: <p>I have a <code>CollectionView</code> derived from an <code>ObservableCollection</code>:</p>
  
  <pre><code>private static ObservableCollection&lt;CalculationViewModel&gt; _calculations;
  
  CalculationViewModelsCollection = (CollectionView)CollectionViewSource.GetDefaultView(_calculations);
  </code></pre>
  
  <p>My problem is that, when the result of the filter is nothing, I'd like to clear the filter, and re-filter with other conditions, but the <code>CollectionView</code> is always empty.</p>
  
  <p>I tried to reset the filter these ways:</p>
  
  <pre><code>CalculationViewModelsCollection.Filter = null;
  CalculationViewModelsCollection.Refresh();
  </code></pre>
  
  <p>and</p>
  
  <pre><code>CalculationViewModelsCollection.Filter = delegate(object p)
  {
      return true;
  };
  </code></pre>
  
  <p>But none of them worked.</p>
  
  <p>Could you give some advice how to reset a filter on a <code>CollectionView</code>?</p>