title: DataGrid replaces first row instead of adding a new row,
body: <p>I have a Datagrid in my WPF that is populated with a by an ObservableCollection on a doubleclick form another DataGrid (users click on preferred title and details DataGrid is populated with the associated data).</p>
  
  <p>Every time I search a new title, and then make a selection, the details DataGrid replaces the first row of data that was already there. How do I make it so that the DataGrid adds a new row so that I can log multiple entities at once for exporting?</p>
  
  <p>My Code Bellow:</p>
  
  <p><strong>DataGrid .cs</strong></p>
  
  <pre><code>// This action will seach the IMDb API for the associated infromation for the IMDBID that is tagged with the title you chose in the ListBox.
     private void Movie_List_MouseDoubleClick(object sender, RoutedEventArgs e)      
  
       {  
          // Grabs the IMDBID associated to the movie title selected to be used with the second API request.
         // DataRowView row = (DataRowView)Movie_List.SelectedItems;
  
  
          string titleID = ((searchInfo)Movie_List.SelectedItem).imdbID;
          string newurl = "http://www.omdbapi.com/?i=" + titleID + "&amp;r=XML";
  
           // Prepares 2nd API URL request to get data for chosen title.
           // Creates a XML Document  to store the xml data that was sent back by the API.
          var doc = XElement.Load(newurl);
  
           // Creates a XML Noedlist to store the values that are going to be associated with the given attribute tag.
          IEnumerable&lt;XElement&gt; movieList = doc.Descendants("movie");
           // Creats an ObservableCollection for the Object Retrievalinfo to be displayed in the Movie_Datagrid, that can be edited.
          ObservableCollection&lt;Retrievalinfo&gt; gridInfo = new ObservableCollection&lt;Retrievalinfo&gt;(movieList.Select(movieElement =&gt;
              new Retrievalinfo()
          {
              title = movieElement.Attribute("title").Value,
              actors = movieElement.Attribute("actors").Value.Split(',').ToList(),
              genre = movieElement.Attribute("genre").Value,
              rated = movieElement.Attribute("rated").Value,
              imdbRating = movieElement.Attribute("imdbRating").Value,
              released = movieElement.Attribute("released").Value,
              runtime = movieElement.Attribute("runtime").Value,
          }));
          Movie_DataGrid.ItemsSource = gridInfo;       
      }
  </code></pre>
  
  <p><strong>Retrievalinfo Class</strong> (Object used for the ObservableCollection)</p>
  
  <pre><code>public class Retrievalinfo
  {
      public Retrievalinfo()
      {
          actors = new List&lt;string&gt;();
      }
  
      //Creating a list of info objects that will store all returned data for selected title.
      public string title { get; set; }
      public List&lt;string&gt; actors { get; set; }
      public string genre { get; set; }
      public string rated { get; set; }
      public string imdbRating { get; set; }
      public string released { get; set; }
      public string runtime { get; set; }
      }
  }
  </code></pre>
  
  <p><strong>DataGird XAML</strong> (Movie_DataGrid, holds the details of the movie selected)</p>
  
  <pre><code>&lt;DataGrid x:Name="Movie_DataGrid"
              Grid.ColumnSpan="2"
              HorizontalAlignment="Left"
              Margin="292,107,0,0"
              VerticalAlignment="Top"
              Height="214"
              Width="673"
              AutoGenerateColumns="False"
              ItemsSource="{Binding gridInfo}"&gt;
                  &lt;DataGrid.Columns&gt;
                      &lt;DataGridTextColumn Header="Title" Binding="{Binding Path=title}"/&gt;
                      &lt;DataGridTextColumn Header="Main Actor 1" Binding="{Binding Path=actors[0]}"/&gt;
                      &lt;DataGridTextColumn Header="Main Actor 2" Binding="{Binding Path=actors[1]}"/&gt;
                      &lt;DataGridTextColumn Header="Main Actor 3" Binding="{Binding Path=actors[2]}"/&gt;
                      &lt;DataGridComboBoxColumn Header="Digital Format" ItemsSource="{Binding digital}"/&gt;
                      &lt;DataGridComboBoxColumn Header="Physical Format" ItemsSource="{Binding physical}"/&gt;
                      &lt;DataGridTextColumn Header="Genre" Binding="{Binding Path=genre}"/&gt;
                      &lt;DataGridTextColumn Header="Rated" Binding="{Binding Path=rated}"/&gt;
                      &lt;DataGridTextColumn Header="IMDB Rating" Binding="{Binding Path=imdbRating}"/&gt;
                      &lt;DataGridTextColumn Header="Released" Binding="{Binding Path=released}"/&gt;
                      &lt;DataGridTextColumn Header="Runtime" Binding="{Binding Path=runtime}"/&gt;
                      &lt;DataGridComboBoxColumn Header="File Type" ItemsSource="{Binding file_type}"/&gt;
              &lt;/DataGrid.Columns&gt;
          &lt;/DataGrid&gt;
  </code></pre>