| Custom Controls > Using the Wijmo Control Extensions > Wijmo Custom Control |
For content items that represent screen content, such as when you add a new custom control to a layout element, you can substitute a Wijmo Custom Control and set its Widget property to one of the available values. The following table shows the mapping between the property value and the underlying UI element.
| Widget Property | Base Control |
| JSON Chart | wijbarchart |
| JSON Grid | wijgrid |
Both the JSON Chart and JSON Grid widgets are used in the Wijmo OLAP Screen template. They are so named because they do not bind to screen collections, but instead receive data from a call to the jQuery method getJSON. The OLAP screen template assumes that these widgets will get data from a Web API controller in the Server project that was created with the OLAP Server for LightSwitch package. However, they will work with any URL that returns tabular JSON-encoded data.
The default setting for the Widget property is JSON Grid.
Although the JSON Chart widget creates an instance of the wijbarchart control by default, you can change the generated script code to use wijlinechart or wijscatterchart instead.