title: Group Item in Kendo UI Combobox
body: <p>I want to grouping item in Kendo UI combobox.</p>
  
  <p>My datasoure is - </p>
  
  <pre><code>$("#ddlTest_I").kendoComboBox({
          dataTextField: "parentName",
          dataValueField: "parentId",
          dataSource: [
                  { parentName: "Parent1", parentId: 1, childName: "Child1", childId: 1 },
                  { parentName: "Parent2", parentId: 2, childName: "Child2", childId: 2 },
                  { parentName: "Parent1", parentId: 1, childName: "Child3", childId: 3 },
                  { parentName: "Parent2", parentId: 2, childName: "Child4", childId: 4 },
                  { parentName: "Parent1", parentId: 1, childName: "Child5", childId: 5 }
              ]
      });
  </code></pre>
  
  <p>I try data bind to Kendo UI combobox -</p>
  
  <pre><code>$("#ddlTest_II").kendoComboBox({
          cascadeFrom: "ddlTest_I",
          dataTextField: "childName",
          dataValueField: "childId",
          dataSource: [            
                  {parentName: "Parent1", parentId: 1, childName: "Child1", childId: 1 },
                  { parentName: "Parent2", parentId: 2, childName: "Child2", childId: 2 },
                  { parentName: "Parent1", parentId: 1, childName: "Child3", childId: 3 },
                  { parentName: "Parent2", parentId: 2, childName: "Child4", childId: 4 },
                  { parentName: "Parent1", parentId: 1, childName: "Child5", childId: 5 }
              ]
      });   
  </code></pre>
  
  <p>I want to use KendoUI combobox cascadeFrom format.But items are duplicate at parent.</p>
  
  <p>This is sample.I don't want twice to pull data from DB. I collected all data in one source to use.</p>