Activity form
Completing the Steps tab — Iteration

When a step row is not selected, a indicates that this step is iterated. When a step row is selected, clickto add an iteration or theto access the details of the iteration. Use this selection box to indicate whether and how to repeat the step. You can cause the step to repeat a specific number of times, or until a specific result is reached.

Use the Iteration Box to apply the step to more than one page or object. Select:

• For Each Page
• For Each Embedded Page
• For Each Element in Value List
• For Each Element in Value Group
• For Loop

To exit the iteration before processing all elements in the iteration, complete a transition that is true after the last desired element is processed.

When processing the For Loop or iterating over a Value List or Page List property, the parameter param.pyForEachCount holds the current iteration number. You can examine (but not alter) this value in the step. For example, to iterate only over the first ten pages or values, you can exit the iteration when pyForEachCount is greater than 10.

If the body of the iteration requires more than one step to code, create an activity and call the activity in the iterated step. Select the Pass current parameter page? box to share the parameter page of the current activity with the called activity.

Select the For Each Page option to sequence through all pages of a specified class or classes and perform a method or instruction for each page. Leave the Step Page field blank. Each time the step repeats, the step's page changes.

For the optional Valid Classes parameter, enter a class or classes. (Click the Add Row icon beneath the Valid Classes box to add more than one class.)

When Valid Classes is not blank, iteration processing skips over any page with a class that does not appear on the list, or is not derived from one of these classes.

Use For Each Embedded Page option to apply a method or instruction to each embedded page in a Page List or Page Group property. Use the iteration choice to specify processing that is to occur for each embedded page. For example, you can:

• Copy each embedded page
• Delete each embedded page using Page-Remove
• Delete a property on each embedded page
• Add a property to each embedded page

and so on.

Identify the property containing the embedded pages in the Step Page field. The SmartPrompt list for the Step Page field shows only Page List and Page Group properties.

For the optional Valid Classes parameter, enter a class or classes. (Click the Add Row icon beneath the Valid Classes box to add more than one class.)

• When Valid Classes is blank, all pages of the Page List or Page Group are included in the iteration.
• When Valid Classes is not blank, iteration processing skips over any page with a class that does not appear on the list, or is not derived from one of these classes.

Select the For Each Element in a Value List option to repeat the step for each element in a Value List property.

Each time the step repeats, the system applies a method or instruction of your choice (such as Property-Set) to the current property. Use the <current> index value to refer to the current property element.

When you select this iteration form, a Property Name field appears. Identify the Value List property in the Property Name field.

Select the For Each Element in a Value Group option to repeat the step for each element in a Value Group property.

When you select this iteration form, a Property Name field appears. Identify the Value Group property in the Property Name field.

Each time the step repeats, the system applies a method or instruction of your choice to the current property. Use the <current> index value to refer to the current property.

Select the For Loop option to repeat the step a number of times determined by the values of integer constants or integer properties.

Enter integer constant values or integer property references for the Start, Stop, and Increment fields.

The system accesses these three values once before starting the iteration. The iteration may occur zero, one, or many times, repeating until the incremented value is greater than or equal to the stop value (unless a transition causes processing to end earlier).

The symbolic reference <CURRENT> may be used only in the activity step that defines the iteration. If that step calls another activity, the symbolic reference <CURRENT> cannot be used in the called activity; rather, aspects of the current iteration are available on the parameter page of the called activity:

• For a repeat type of For Each Element in a Value List or For Each Element in a Value Group, the symbol <CURRENT> refers to the value of ClipboardProperty corresponding to the iteration. For the called activity, this corresponds to the pyPropertyValue parameter described below.
• For other repeat types, <CURRENT> refers to the index number of the current iteration, and corresponds to the pyForEachCount parameter.

The scope of an iteration can be more than one step. The iteration type and conditions are set in the first step of a multistep iteration.

To create a multistep iteration:

1. Identify the step that is to be first in the iteration. Click in the iteration column to access the Iteration area, and complete the iteration details. The appears in the iteration column.
2. Complete information for the first step. Identify the step page. Optionally, you can leave the method blank.
3. Click Add Child Step (). The current step is renumbered as NNN.0, where NNN was the previous step number. The form changes to include a new later step NNN.1. The scope of the iteration is now both NNN.0 and NNN.1. This zero-numbered step is known as the parent step.
4. Complete NNN.1, a child step. Leave the Step Page field blank and the iteration criteria blank in most cases, to have the child steps operate on the step page identified in the parent step. Optionally, you can override this step page of a child step by entering one of the following:

• a top-level page (such as the primary page).
• A reference to a page relative to the step page of the parent.
• a reference to a Page List or Page Group property on the step page of the parent. (In this case, complete the For Each Embedded Page iteration details for the child step.)

5. To create an iteration of more than two steps, click within the parent step NNN.0 again to make it active, and click the Add Child Step icon ( ) again.

Numbered child steps are executed in sequence NNN.0, NNN.1, NNN.2 ... then NNN.0 again, until the iteration ends or a transition causes a jump to a labeled step.

To convert an iteration sequence to comments, enter two slash characters // in the Label field of the parent step. The parent and all child steps become comments.

You can't jump from outside a multistep iteration to any step within the iteration (except to the starting — parent — step). You can jump from any step in an iteration (parent or child) to a higher-numbered step (that is not within any iteration).

For an example of multistep and nested iterations, see the Pega Developer Network article PRKB-25610 How to use multistep loops and nested loops in activities.

By using the Add Child Step icon ( ) on a child step numbered NNN.Z, you can create a nested iteration.

For example, clicking a child step numbered 14.8 converts this to 14.8.0, and inserts a second-level child step numbered 14.8.1. Complete the iteration conditions for step 14.8.0.

Use care in entering the Step Page for the parent step of a nested iteration (14.8.0 in this example). If you refer to an aggregate property (Value Group, Value List, Page Group or Page List), select a property that reside on the <CURRENT> step page of the parent's parent. (That is, the structure of the iteration must follow the structure of the page).

From within a nested iteration, you can jump (using a transition) to a labeled step that is within an outer iteration but higher numbered. You can jump from 14.8.9 to 14.10 or 17, but not from 14.8.9 to 14.3.

If a step is part of an iteration sequence, the method cannot be any of the following:

Process Commander automatically adds the following parameters to the parameter page of a called activity with a step that contains an iteration. (These parameter values are not available to other methods in an iteration step.)

• pyForEachCount — Index of the current iteration, normally starting at 1 and incrementing by one. (If the iteration type is For Loop, the starting value may be a value other than 1 and the increment may be a value other than 1.)
• pyIterationType — Indicates the iteration type, internally represented by one of the constants page, embedded, propertylist, propertygroup, or repeat.
• pyIterationTarget — Identifies the name or reference of the iteration. For page and repeat types, it is blank. For embedded, it is the step page reference. For propertylist or propertygroup, it is the property specified in the iteration.
• pyPropertyValue — Available only for propertylist and propertygroup iterations. The text value of the current property.
• pyPropertyReference — Obsolete. Set to "???" for backward compatibility.
• pyPropertyType — Obsolete. Set to "???" for backward compatibility.