Defining conditions for an ECA rule

This topic describes how to configure the conditions part of an ECA rule for widgets.

Figure 1. The Condition panel of the ECA editor

A condition must be specified for every ECA rule. A condition is the part of an ECA rule that performs a logical test that causes the actions that are defined in the "Actions if true" part of the ECA editor to be carried out if it evaluates to true. If the condition part of an ECA rule evaluates to false, the actions that are defined in the "Actions if false" part of the ECA editor are carried out. For information on how to define actions in the ECA editor for an ECA rule, see Defining actions for an ECA rule.

As shown in Figure 1, the following conditions are available for selection in the Rules tab of the XUI editor:

No Condition

If No Condition is selected, the systems executes the true action by default.

Widget Function

Each widget has a function. The Widget Function option allows you to specify the function that is bound to a widget. In most situations, the widget function returns a Boolean value. The system will then call either a true or a false action depending on the value that is returned.
Note: If you specify a function for a widget, you must click Apply Value in the Conditions panel to bind the function to the widget.

Widget Property

The Widget Property option allows you to configure a condition to the property of a widget. This condition is the same as the Widget Function condition type, there will be a return value. This condition will return two value types : String and Boolean. Usually, system will call true or false action according to the Boolean value. But now there is a string type return value, so how the system calls relative action. Only Boolean type action existed, not String type action. In view of this situation, the system will execute the true action by default, once the condition return value is string type.
Note: After you select a property in the Widget Property panel, you must click Apply Value to configure a condition for the widget property.

Expression

The outer operator is arithmetic, which can include only the following operators in the expression: addition, subtraction, multiplication and division. However, if you select a logical operator in outer expression, logical and arithmetic operators are displayed in the expression.

As an example, you can use an expression in the condition part of the ECA editor if you want to create a rule in which a text box cannot be empty when it is being filled by a user. In this example, you would create a rule in which a text box cannot be empty by doing the following steps:
  1. In the Condition drop-down list, select Expression.
  2. In the Left field of the Expression panel, click the Browse icon. The "Please select a value" window is opened.
  3. In the drop-down list in the "Please select a value" window, select Widget Property. The Widget Property panel is displayed.
  4. In the Widget Property panel, select the text box widget, and then select value. Click OK.
  5. In the Operator drop-down list of the Expression panel, select !=.
  6. In the Right field of the Expression panel, click the Browse icon. The "Please select a value" window is opened.
  7. In the drop-down list in the "Please select a value" window, select Constant. The Constant panel is displayed.
  8. In the Value field of the Constant panel, enter an opening quotation mark ("). Click OK.
  9. In the Condition panel, click Apply Value.