Understanding a rule
A rule is a combination of actions and conditions. In rule editor, actions include activities such as hide, show, enable, disable, or compute the value of an object in a form. Conditions are Boolean expressions that are evaluated by performing checks and operations on the state, value, or property of a form object. Actions are performed based on the value ( True or False) returned by evaluating a condition.
The rule editor provides a set of predefined rule types, such as When, Show, Hide, Enable, Disable, Set Value Of, and Validate to help you write rules. Each rule type lets you define conditions and actions in a rule. The document further explains each rule type in detail.
A rule typically follows one of the following constructs:
Condition-Action In this construct, a rule first defines a condition followed by an action to trigger. The construct is comparable to if-then statement in programming languages.
In rule editor, the When rule type enforces the condition-action construct.
Action-Condition In this construct, a rule first defines an action to trigger followed by conditions for evaluation. Another variation of this construct is action-condition-alternate action, which also defines an alternate action to trigger if the condition returns False.
The Show, Hide, Enable, Disable, Set Value Of, and Validate rule types in rule editor enforce the action-condition rule construct. By default, the alternate action for Show is Hide and for Enable is Disable, and conversely. You cannot change the default alternate action.
NOTEFor more information about rule types available in the rule editor, see Available rule types in rule editor.
Guidelines for choosing a rule construct
While you can achieve most of the use cases by using any rule construct, here are some guidelines to choose one construct over another. For more information about the available rules in rule editor, see Available rule types in rule editor.
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A typical rule of the thumb when creating a rule is to think about it in the context of the object on which you are writing a rule. Consider that you want to hide or show the field B based on the value a user specifies in the field A. In this case, you are evaluating a condition on field A, and based on the value it returns, you are triggering an action on field B.
Therefore, if you are writing a rule on field B (the object on which you are evaluating a condition), use the condition-action construct or the When rule type. Similarly, use the action-condition construct or Show or Hide rule type on field A.
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At times, you need to perform multiple actions based on one condition. In such cases, it is recommended to use the condition-action construct. In this construct, you can evaluate a condition once and specify multiple action statements.
For example, to hide fields B, C, and D based on the condition that checks for the value a user specifies in field A, write one rule with condition-action construct or When rule type on field A and specify actions to control the visibility of fields B, C, and D. Otherwise, you need three separate rules on fields B, C, and D, where each rule checks the condition and shows or hides the respective field. In this example, it is more efficient to write the When rule type on one object rather than Show or Hide rule type on three objects.
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To trigger an action based on multiple conditions, it is recommended to use action-condition construct. For example, to show and hide field A by evaluating conditions on fields B, C, and D, use Show or Hide rule type on field A.
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Use condition-action or action condition construct if the rule contains one action for one condition.
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If a rule checks for a condition and performs an action immediately on providing a value in a field or exiting a field, it is recommended to write a rule with condition-action construct or the When rule type on the field on which the condition is evaluated.
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The condition in the When rule is evaluated when a user changes the value of the object on which the When rule is applied. However, if you want the action to trigger when the value changes on the server side, like in prepopulating the value, it is recommended to write a When rule that triggers the action when the field is initialized.
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When writing rules for drop-downs, radio buttons, or check boxes objects, the options or values of these form objects in the form are pre-populated in the rule editor.
Available operator types and events in rule editor
The rule editor provides the following logical operators and events using which you can create rules.
- Is Equal To
- Is Not Equal To
- Starts With
- Ends With
- Contains
- Is Empty
- Is Not Empty
- Has Selected: Returns true when the user selects a particular option for a checkbox, drop-down, radio button.
- Is Initialized (event): Returns true when a form object renders in the browser.
- Is Changed (event): Returns true when the user changes the entered value or selected option for a form object.
Available rule types in rule editor
The rule editor provides a set of predefined rule types that you can use to write rules. Let’s look at each rule type in detail. For more information about writing rules in rule editor, see Write rules.
When
The When rule type follows the condition-action-alternate action rule construct, or sometimes, just the condition-action construct. In this rule type, you first specify a condition for evaluation followed by an action to trigger if the condition is satisfied ( True). While using the When rule type, you can use multiple AND and OR operators to create nested expressions.
Using the When rule type, you can evaluate a condition on a form object and perform actions on one or more objects.
In plain words, a typical When rule is structured as follows:
When on Object A:
(Condition 1 AND Condition 2 OR Condition 3) is TRUE;
Then, do the following:
Action 2 on Object B;
AND
Action 3 on Object C;
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When you have a multi-value component, such as radio buttons or list, while creating a rule for that component the options are automatically retrieved and made available to the rule creator. You do not need to type the option values again.
For example, a list has four options: Red, Blue, Green, and Yellow. While creating the rule, the options (radio buttons) are automatically retrieved and made available to the rule creator as following:
While writing a When rule, you can trigger the Clear Value Of action. Clear Value Of action clears the value of the specified object. Having Clear Value of as an option in the When statement lets you create complex conditions with multiple fields.
Hide Hides the specified object.
Show Shows the specified object.
Enable Enables the specified object.
Disable Disables the specified object.
Invoke service Invokes a service configured in a form data model. When you choose the Invoke Service operation, a field appears. On tapping the field, it displays all services configured in all form data models on your AEM instance. On choosing a form data model service, additional fields appear where you can map form objects with input and output parameters for the specified service. See example rule for invoking form data model services.
In addition to form data model service, you can specify a direct WSDL URL to invoke a web service. However, a form data model service has many benefits and the recommended approach to invoke a service.
For more information about configuring services in form data model, see AEM Forms Data Integration.
Set value of Computes and sets the value of the specified object. You can set the object value to a string, the value of another object, the computed value using mathematical expression or function, the value of a property of an object, or the output value from a configured form data model service. When you choose the web service option, it displays all services configured in all form data models on your AEM instance. On choosing a form data model service, additional fields appear where you can map form objects with input and output parameters for the specified service.
For more information about configuring services in form data model, see AEM Forms Data Integration.
The Set Property rule type lets you set the value of a property of the specified object based on a condition action. You can set property to one of the following:
- visible (Boolean)
- dorExclusion (Boolean)
- chartType (String)
- title (String)
- enabled (Boolean)
- mandatory (Boolean)
- validationsDisabled (Boolean)
- validateExpMessage (String)
- value (Number, String, Date)
- items (List)
- valid (Boolean)
- errorMessage (String)
It enables you to define rules to add check boxes dynamically to the adaptive form. You can use custom function, a form object, or an object property to define a rule.
To define a rule based on a custom function, select Function Output from the drop-down list, and drag-and-drop a custom function from the Functions tab. If the condition action is met, the number of checkboxes defined in the custom function are added to the adaptive form.
To define a rule based on a form object, select Form Object from the drop-down list, and drag-and-drop a form object from the Form Objects tab. If the condition action is met, the number of checkboxes defined in the form object are added to the adaptive form.
A Set Property rule based on an object property lets you add the number of checkboxes in an adaptive form based on another object property that is included in the adaptive form.
The following figure depicts an example of dynamically adding checkboxes based on the number of drop-down lists in the adaptive form:
Clear Value Of Clears the value of the specified object.
Set Focus Sets focus on the specified object.
Save Form Saves the form.
Submit Forms Submits the form.
Reset Form Resets the form.
Validate Form Validates the form.
Add Instance Adds an instance of the specified repeatable panel or table row.
Remove Instance Removes an instance of the specified repeatable panel or table row.
Navigate to Navigates to other Interactive Communications, adaptive forms, other assets such as images or document fragments, or an external URL. For more information, see Add button to the Interactive Communication.
Set Value of
The Set Value of rule type lets you set the value of a form object depending on whether the specified condition is satisfied or not. The value can be set to a value of another object, a literal string, a value derived from a mathematical expression or a function, a value of a property of another object, or the output of a form data model service. Similarly, you can check for a condition on a component, string, property, or values derived from a function or mathematical expression.
The Set Value Of rule type is not available for all form objects, such as panels and toolbar buttons. A standard Set Value Of rule has the following structure:
Set value of Object A to:
(string ABC) OR
(object property X of Object C) OR
(value from a function) OR
(value from a mathematical expression) OR
(output value of a data model service or web service);
When (optional):
(Condition 1 AND Condition 2 AND Condition 3) is TRUE;
The following example takes the value in dependentid field as input and sets the value of the Relation field to the output of the Relation argument of the getDependent form data model service.
Example of Set Value rule using form data model service
NOTEShow
Using the Show rule type, you can write a rule to show or hide a form object based on whether a condition is satisfied or not. The Show rule type also triggers the Hide action in case the condition is not satisfied or returns False.
A typical Show rule is structured as follows:
Show Object A;
When:
(Condition 1 OR Condition 2 OR Condition 3) is TRUE;
Else:
Hide Object A;
Hide
Similar to the Show rule type, you can use the Hide rule type to show or hide a form object based on whether a condition is satisfied or not. The Hide rule type also triggers the Show action in case the condition is not satisfied or returns False.
A typical Hide rule is structured as follows:
Hide Object A;
When:
(Condition 1 AND Condition 2 AND Condition 3) is TRUE;
Else:
Show Object A;
Enable
The Enable rule type lets you enable or disable a form object based on whether a condition is satisfied or not. The Enable rule type also triggers the Disable action in case the condition is not satisfied or returns False.
A typical Enable rule is structured as follows:
Enable Object A;
When:
(Condition 1 AND Condition 2 AND Condition 3) is TRUE;
Else:
Disable Object A;
Disable
Similar to the Enable rule type, the Disable rule type lets you enable or disable a form object based on whether a condition is satisfied or not. The Disable rule type also triggers the Enable action in case the condition is not satisfied or returns False.
A typical Disable rule is structured as follows:
Disable Object A;
When:
(Condition 1 OR Condition 2 OR Condition 3) is TRUE;
Else:
Enable Object A;
Validate
The Validate rule type validates the value in a field using an expression. For example, you can write an expression to check that the text box for specifying name does not contain special characters or numbers.
A typical Validate rule is structured as follows:
Validate Object A;
Using:
(Expression 1 AND Expression 2 AND Expression 3) is TRUE;
NOTE
Set Options Of
The Set Options Of rule type enables you to define rules to add check boxes dynamically to the adaptive form. You can use a form data model or a custom function to define the rule.
To define a rule based on a custom function, select Function Output from the drop-down list, and drag-and-drop a custom function from the Functions tab. The number of checkboxes defined in the custom function are added to the adaptive form.
To create a custom function, see custom functions in rule editor.
To define a rule based on a form data model:
- Select Service Output from the drop-down list.
- Select the data model object.
- Select a data model object property from the Display Value drop-down list. The number of checkboxes in the adaptive form is derived from the number of instances defined for that property in the database.
- Select a data model object property from the Save Value drop-down list.
Understanding the rule editor user interface
Rule editor provides a comprehensive yet simple user interface to write and manage rules. You can launch the rule editor user interface from within an adaptive form in authoring mode.
To launch the rule editor user interface:
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Open an adaptive form in authoring mode.
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Select the form object for which you want to write a rule, and in Component Toolbar select
Any existing rules on the selected form objects are listed in this view. For information about managing existing rules, see Manage rules.
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Select Create to write a new rule. The visual editor of the rule editor user interface opens by default when you launch the rule editor the first time.
Let’s look at each component of the rule editor UI in detail.
A. Component-rule display
Displays the title of the adaptive form object through which you launched the rule editor and the rule type currently selected. In the above example, the rule editor is launched from an adaptive form object titled Salary and the rule type selected is When.
B. Form objects and functions
The pane on the left in the rule editor user interface includes two tabs — Forms Objects and Functions.
The Form Objects tab shows a hierarchical view of all objects contained in the adaptive form. It displays the title and type of the objects. When writing a rule, you can drag-drop form objects onto the rule editor. While creating or editing a rule when you drag-and-drop an object or function into a placeholder, the placeholder automatically takes the appropriate value type.
The form objects that have one or more valid rules applied are marked with a Green dot. If any of the rules applied to a form object is invalid, the form object is marked with a Yellow dot.
The Functions tab includes a set of built-in functions, such as Sum Of, Min Of, Max Of, Average Of, Number Of, and Validate Form. You can use these functions to compute values in repeatable panels and table rows and use them in action and condition statements when writing rules. You can, however, create custom functions too.
NOTEIn the left tree of the form objects, you can select the form objects to display the rules applied to each of the objects. Not only you can navigate through the rules of the various form objects, you can also copy-paste rules between the form objects. For more information, see Copy-paste rules.
C. Form objects and functions toggle
The toggle button, when tapped, toggles the form objects and functions pane.
D. Visual rule editor
Visual rule editor is the area in the visual editor mode of the rule editor user interface where you write rules. It lets you select a rule type and accordingly define conditions and actions. When defining conditions and actions in a rule, you can drag-drop form objects and functions from the Form Objects and Functions pane.
For more information about using visual rule editor, see Write rules.
E. Visual-code editors switcher
Users in the forms-power-users group can access code editor. For other users, code editor is not available. If you have the rights, you can switch from visual editor mode to code editor mode of the rule editor, and conversely, using the switcher right above the rule editor. When you launch rule editor the first time, it opens in the visual editor mode. You can write rules in the visual editor mode or switch to the code editor mode to write a rule script. However, note that if you modify a rule or write a rule in code editor, you cannot switch back to the visual editor for that rule unless you clear the code editor.
AEM Forms tracks the rule editor mode you used last to write a rule. When you launch the rule editor next time, it opens in that mode. However, you can also configure a default mode to open the rule editor in the specified mode. To do so:
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Go to AEM web console at
https://[host]:[port]/system/console/configMgr. -
Click to edit Adaptive Form and Interactive Communication Web Channel Configuration.
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choose Visual Editor or Code Editor from the Default Mode for Rule Editor drop-down
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Click Save.
F. Done and cancel buttons
The Done button is used to save a rule. You can save an incomplete rule. However, incomplete are invalid and do not run. Saved rules on a form object are listed when you launch the rule editor next time from the same form object. You can manage existing rules in that view. For more information, see Manage rules.
The Cancel button discards any changes you made to a rule and closes the rule editor.
Write rules
You can write rules using the visual rule editor or the code editor. When you launch the rule editor the first time, it opens in the visual editor mode. You can switch to the code editor mode and write rules. However, note that if you write or modify a rule in code editor, you cannot switch to the visual editor for that rule unless you clear the code editor. When you launch the rule editor next time, it opens in the mode that you used last to create rule.
Let’s first look at how to write rules using visual editor.
Using visual editor
Let’s understand how to create a rule in visual editor using the following example form.
The Loan Requirements section in the example loan application form requires applicants to specify their marital status, salary, and if married, their spouse’s salary. Based on the user inputs, the rule computes the loan eligibility amount and displays in the Loan Eligibility field. Apply the following rules to implement the scenario:
- The Spouse’s Salary field is shown only when the Marital Status is Married.
- The loan eligibility amount is 50% of the total salary.
Perform the following steps to write rules:
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First, write the rule to control the visibility of the Spouse Salary field based on the option user selects for the Marital Status radio button.
Open the loan application form in authoring mode. Select the Marital Status component and select
When you launch the rule editor, the When rule is selected by default. Also, the form object (in this case, Marital Status) from where you launched the rule editor is specified in the When statement.
While you cannot change or modify the selected object, you can use the rule drop-down, as shown below, to select another rule type. If you want to create a rule on another object, select Cancel to exit the rule editor and launch it again from the desired form object.
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Select Select State drop-down and select is equal to. The Enter a String field appears.
In the Marital Status radio button, Married and Single options are assigned 0 and 1 values, respectively. You can verify assigned values in the Title tab of the Edit radio button dialog as shown below.
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In the Enter a String field in the rule, specify 0.
You have defined the condition as
When Marital Status is equal to Married. Next, define the action to perform if this condition is True. -
In the Then statement, select Show from the Select Action drop-down.
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Drag-drop the Spouse Salary field from the Form Objects tab on the Drop object or select here field. Alternatively, select the Drop object or select here field and select the Spouse Salary field from the pop-up menu, which lists all form objects in the form.
The rule appears as follows in the rule editor.
Select Done to save the rule.
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Repeat steps 1 through 5 to define another rule to hide the Spouse Salary field if the marital Status is Single. The rule appears as follows in the rule editor.
NOTEAlternatively, you can write one Show rule on the Spouse Salary field, instead of two When rules on the Marital Status field, to implement the same behavior.
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Next, write a rule to compute the loan eligibility amount, which is 50% of the total salary, and display it in the Loan Eligibility field. To achieve this, create Set value Of rules on Loan Eligibility field.
In authoring mode, select the Loan Eligibility field and select
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Select Set Value Of rule from the rule drop-down.
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Select Select Option and select Mathematical Expression. A field to write mathematical expression opens.
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In the expression field:
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Select or drag-drop from the Forms Object tab the Salary field in the first Drop object or select here field.
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Select Plus from the Select Operator field.
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Select or drag-drop from the Forms Object tab the Spouse Salary field in the other Drop object or select here field.
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Next, select in the highlighted area around the expression field and select Extend Expression.
In the extended expression field, select divided by from the Select Operator field and Number from the Select Option field. Then, specify 2 in the number field.
NOTEYou can create complex expressions by using components, functions, mathematical expressions, and property values from the Select Option field.Next, create a condition, which when returns True, the expression executes.
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Select Add Condition to add a When statement.
In the When statement:
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Select or drag-drop from the Forms Object tab the Marital Status field in the first Drop object or select here field.
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Select i s equal to from the Select Operator field.
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Select String in the other Drop object or select here field and specify Married in the Enter a String field.
The rule finally appears as follows in the rule editor.
Select Done to save the rule.
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Repeat steps 7 through 12 to define another rule to compute the loan eligibility if the marital Status is Single. The rule appears as follows in the rule editor.
NOTE
