Selectors in UI Automation: how they identify UI elements, tag structure, attribute types, and best practices.

To automate specific actions in the user interface, you are required to interact with various windows, buttons, drop-down lists and many others. One of the ways in which UI elements can be identified is by using their position on the screen, but this can be unreliable.

To overcome this problem, Studio uses what we call selectors. These store the attributes of a graphical user interface element and its parents, in the shape of an XML fragment.

Most of the times, selectors are automatically generated by Studio and do not require further input from you, especially if the apps you are trying to automate have a static user interface.

However, some software programs have changing layouts and attribute nodes with volatile values, such as some web-apps. Studio cannot predict these changes and, therefore, you might have to manually generate some selectors.

A selector has the following structure:

The last node represents the GUI element that interests you, and all the previous ones represent the parents of that element. <node_1> is usually referred to as a root node, and represents the top window of the app.

Each node has one or more attributes that help you correctly identify a specific level of the selected application.

Each node has the following format:

Every attribute has an assigned value. It is important to pick attributes with a constant value. If the value of an attribute changes each time the app is started, then the selector will not be able to correctly identify the element.

Selectors are displayed in the Properties panel of activities, under Input > Target > Selector. All activities related to graphical elements have this property.

The Selection Options window enables you to select and edit a target. To access this window, in the Workflow Designer panel, click the Options button in the body of an activity and select Indicate target on screen or Edit target.

The Selector Editor window enables you to see the automatically-generated selector and edit it and its attributes. To access this window, use the Ellipsis button next to the Selector field, in the Properties panel.

The following tables present the compatibility between tags and attributes used to build selectors and the selector capability.

On macOS the selector types wnd, ax, java, and sap can be used for different use cases:

The tag and idx attributes use string values. All other WEBCTRL attributes have dynamic values.

Please note that the Silverlight tag does not support Fuzzy, RegEx, and Case-Sensitive capabilities.

The RDP tag is used for remote automation and its attributes are identical to WND tag.