Widget developer guide

Develop custom widgets in the Service Portal using AngularJS, Bootstrap, and the ServiceNow API.

What to know before you begin

To develop widgets, you need ServiceNow API experience to:
  • Run record queries on the server.
  • Create and update records.
You need AngularJS experience to:
  • Bind variables to client controllers.
  • Access server objects in a widget.
  • Gather user input.

Parts of a widget

Like Angular directives, widgets execute a specified behavior within a Service Portal page. A widget includes:

HTML template

A mandatory widget component.

The HTML template requires knowledge of AngularJS to display and gather data. Use the HTML template to:

  • Render the dynamic view that a user sees in the browser using information from the model and controller.
  • Bind client script variables to your markup.
  • Gather data from the end user.
Client script

A mandatory widget component.

A client script requires knowledge of both the ServiceNow API and AngularJS to create a client controller. Use the client script to:

  • Map server data from JavaScript and JSON objects to client objects.
  • Process data before rendering it.
  • Pass data to the HTML template.
  • Pass user input and data back to the server for processing.
Server script

A mandatory widget component.

A server script requires knowledge of the ServiceNow API to work with record data. Use the server script to:

  • Set the initial state of the widget.
  • Send record data to the widget client script using the data variable.
  • Run server-side queries.
Link function

An optional widget component.

The link function requires knowledge of AngularJS. Use a link function to directly manipulate the DOM.

Option schema

An optional widget component.

Allows a Service Portal admin to configure a widget. Use the option schema to:

  • Specify the parameters for a widget.
  • Allow admin users to define instance options for a widget instance.
  • Develop flexible, reusable widgets.
Angular Providers

An optional widget component.

Angular Providers require knowledge of AngularJS. Use Angular Providers to:

  • Keep widgets in sync when changing records or filters.
  • Share context between widgets.
  • Maintain and persist state.
  • Create reusable behaviors and UI components and inject them into multiple widgets.
Dependencies

An optional widget component.

A widget dependency is an external resource used by your widget such as JavaScript or CSS files.

Global objects in widgets

When a widget begins to render for the first time on a page, the server script executes first and accesses three global objects: input, options, and data. Because the input variable is a data object sent from the client script, this variable is undefined when first initialized.

Available variables in server and client script global

When a widget is first instantiated, the server script:

  1. Initializes an empty data object.
  2. Initializes the input object with any data sent from the client controller, or the options object with any data used to initialize the widget.
  3. Sends the data object to the client controller as JSON.

The client script:

  1. Accesses the server data object using c.data.

    Note: By default, widgets use the c variable to represent the controller instance using controller as syntax. You can change this variable when creating or cloning widgets.
  2. Uses server.update() to post changes to the data model. This method updates the server script using the input object.

    Note: After calling server.update(), the client script data object is automatically overwritten by the server script data object.
  3. Uses c.options to access the values used to invoke the widget on the server. This object is read-only.

Using the Widget Editor

When you create a widget, a record is created in the sp_widget table. However, you can use the Widget Editor in Service Portal Configuration as your scripting environment. The Widget Editor is a full page application similar to an IDE. You can show the parts of the widget you want to edit and hide the rest, while previewing your changes in real time.

Widget editor with the calculator widget showing script examples for the HTML template, CSS, Client script, and the server script