title: WPF - Checkbox bound to whether or not ObservableCollection contains a value?
body: <p>I currently have a checkbox that is bound to a property that checks an ObservableCollection for a specific value.  If the value exists, then the property returns true.</p>
  
  <p>My property and the property that exposes the ObservableCollection are both readonly.</p>
  
  <p>This approach works fine when I first load my model, but when it add additional items into the ObservableCollection the checkbox that is bound to the property does not update.</p>
  
  <p>Here's the code for my property:</p>
  
  <pre><code>public bool IsMeasure11
  {
      get //readonly
      {
         return this.Charges.Any(t =&gt; t.IsMeasure11);
      }
  }
  </code></pre>
  
  <p>And here's the code for my ObservableCollection:</p>
  
  <pre><code>public ObservableCollection&lt;DACharge&gt; Charges
  {
      get //readonly
      {
          if (_charges == null)
          {
               _charges = new GenericEntityCollection&lt;DACharge&gt;(_DACase.Id).ToList().ToObservableCollection();
          }
  
          return _charges;
      }
  }
  </code></pre>
  
  <p>And the XAML for the Checkbox:</p>
  
  <pre><code>&lt;CheckBox Content="M11" Name="chkM11" IsChecked="{Binding IsMeasure11, Mode=OneWay}"&gt;
  </code></pre>
  
  <p>Thanks in advance,<br />
  Sonny</p>