title: Devextreme datagarid : default value of column cells when whith lookup
body: <p>i'am using <strong>devextreme</strong> <strong>datagrid</strong> under my <strong>Angular 5</strong> app.</p>
  
  <p>My <strong>datagrid</strong> looks like this :</p>
  
  <pre><code>&lt;dx-data-grid
      #positionsDataGrid
      id="positionsDataGrid"
      [dataSource]="positionsDataSource"
      keyExpr="id"
      [allowColumnReordering]="true"
      [showBorders]="true"
      loadPanel="false"&gt;
  
      &lt;dxo-paging [enabled]="true"&gt;&lt;/dxo-paging&gt;
      &lt;dxo-editing
        mode="row"
        [allowUpdating]="true"
        [allowDeleting]="true"
        [allowAdding]="true"&gt;
      &lt;/dxo-editing&gt;
  
      &lt;dxi-column dataField="id" caption="ID" [allowEditing]="false" [visible]="false"&gt;&lt;/dxi-column&gt;
      &lt;dxi-column dataField="Cuid" caption="name" [allowEditing]="false"&gt;&lt;/dxi-column&gt;
  
      &lt;dxi-column
        dataField="storeName"
        caption="Boutique"
        [width]="400"
        [setCellValue]="preSelectShop"&gt;
        &lt;dxo-lookup&gt;
          &lt;[dataSource]="shops"&gt;
          &lt;displayExpr="storeName&gt;
          &lt;valueExpr="ID"&gt;&gt;
        &lt;/dxo-lookup&gt;
      &lt;/dxi-column&gt;
  
    &lt;/dx-data-grid&gt;
  </code></pre>
  
  <p>i'am loading <strong>initial data</strong> from a WS (under '<strong>positionsDataSource</strong>' var ) :</p>
  
  <pre><code>  [{
      'id': '2',
      'name': 'test',
      'storeName': 'ABBEVILLE',
    }]
  </code></pre>
  
  <p>the default values cells of the column "<strong>storeName</strong>" din't appear </p>
  
  <p>(but when <strong>EDIT</strong> mode ; the values re-appear)</p>
  
  <p>My purpose is how to make the default values appear.</p>
  
  <p><strong>Suggestions?</strong></p>