# C1.DataCollection.C1CacheDataCollection-1.OnCollectionChanging

## Content

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<h1 id="C1_DataCollection_C1CacheDataCollection_1_OnCollectionChanging_" data-uid="C1.DataCollection.C1CacheDataCollection`1.OnCollectionChanging*">OnCollectionChanging Method
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<div class="markdown level0 summary"></div>
<div class="markdown level0 conceptual"></div>



<a id="C1_DataCollection_C1CacheDataCollection_1_OnCollectionChanging_" data-uid="C1.DataCollection.C1CacheDataCollection`1.OnCollectionChanging*"></a>
<h4 id="C1_DataCollection_C1CacheDataCollection_1_OnCollectionChanging_System_Collections_Specialized_NotifyCollectionChangedEventArgs_" data-uid="C1.DataCollection.C1CacheDataCollection`1.OnCollectionChanging(System.Collections.Specialized.NotifyCollectionChangedEventArgs)">OnCollectionChanging(NotifyCollectionChangedEventArgs)</h4>
<div class="markdown level1 summary"><p>Raises the <span class="xref">CollectionChanging</span> event.</p>
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<div class="markdown level1 conceptual"></div>
<h5 class="declaration">Declaration</h5>
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  <pre><code class="lang-csharp hljs">protected virtual void OnCollectionChanging(NotifyCollectionChangedEventArgs e)</code></pre>
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  <pre><code class="lang-vbnet hljs">Protected Overridable Sub OnCollectionChanging(e As NotifyCollectionChangedEventArgs)</code></pre>
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<h5 class="parameters">Parameters</h5>
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      <th>Type</th>
      <th>Name</th>
      <th>Description</th>
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      <td><a class="xref" href="https://learn.microsoft.com/dotnet/api/system.collections.specialized.notifycollectionchangedeventargs">NotifyCollectionChangedEventArgs</a></td>
      <td><span class="parametername">e</span></td>
      <td><p>The <a class="xref" href="https://learn.microsoft.com/dotnet/api/system.collections.specialized.notifycollectionchangedeventargs">NotifyCollectionChangedEventArgs</a> instance containing the event data.</p>
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