How to: Add a Custom Control to an HTML Screen for a LightSwitch App

Article
11/19/2013

You can add custom HTML controls to a screen in a client for a LightSwitch app. By using custom controls, you can display or collect information in ways that go beyond the capabilities of the built-in HTML controls for LightSwitch.

Referencing Custom Controls

To use a custom control on a screen, you must first add a file reference to the project, and then you add a script tag to the default.htm file.

To reference a custom control

In Solution Explorer, choose File View from the list on the toolbar.
Open the shortcut menu for the Scripts folder, choose Add, and then choose Existing Item.
Choose the JavaScript (.js) file for the custom control, and then choose the Add button.

Note

Some custom controls require that you also reference additional support files. Consult the documentation for the custom control for any requirements.
In the <script> section of the default.htm file for your project, add a script tag that resembles the following example, where MyControl is the name of your custom control:
```
<script type=”text/javascript” src=”Scripts/MyControl.js” charset=”utf-8”></script>
```

Adding New Controls and Replacing Existing Controls

You can add a new custom control to a screen or replace an existing HTML control in LightSwitch.

To add a custom control to a screen

In the Screen Content Tree, choose any group.
On the Screen Designer toolbar, in the Add Layout Item list, choose Custom Control.

The Add Custom Control dialog box opens.
In the Specify the data for the new custom control text box, enter the item or collection to be bound to the control.

For example, enter Customers.selectedItem.PostalCode to bind to a customer’s postal code, or enter Customers.selectedItem to bind to the entire customer record.
Add code that binds the data to a specific property of the control.

For more information, see Binding Data to a Property of the Custom Control later in this topic.

To replace an existing control with a custom control

In the Screen Content Tree, choose the control that you want to replace.
In the Properties window, open the Control Type list, and then choose Custom Control.
Add code that binds the data to a specific property of the control.

For more information, see Binding Data to a Property of the Custom Control later in this topic.

Binding Data to a Property of the Custom Control

You must bind the data that you specified in the Add Custom Control dialog box to a specific property of the custom control.

To bind data to a property of the custom control

In the Screen Content Tree, choose the custom control.
In the Properties window, choose the Edit Render Code hyperlink.
In the code editor, add code that resembles the following example to the render method:
```
createMyControl(element, contentItem, “max-width: 300px; max-height: 300px”);
```
This code renders the control at run time. Replace MyControl with the name of your control, and change the max-height and max-width parameters as necessary.
Add code for any additional functionality that the control requires. Consult the documentation for the custom control for any requirements.

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