Binding to properties in NativeScript

On pageLoaded I bind the xml page binding Context

  page.bindingContext = viewModel;

I view a property in the .js with this statement and it displays correctly with the correct data.

  dialogs.alert(viewModel.jobItem["OpDtlDesc"]);

In the xml I readily bind to the properties with this syntax where jobItem is one of the objects in viewModel.

  <Label text="{{ jobItem.OpDtlDesc }}" />   

I would like to bind to the property in the same fashion as I do in the javascript. 

   <Label text='{ jobItem["OpDtlDesc"] }}' />  

 How do I do this?