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Creating classes

Updated on November 18, 2021

For improved development and maintenance of your application, organize the rules and other objects in your application into classes. By creating classes, you define collections of objects that are available to other classes or to instances of the class. You can reuse classes, and as a result reduce both development time and costs.

In the header of Dev Studio, click CreateSysAdminClass.
In the Class record configuration section, in the Label field, enter a short description for the class that you want to create.
In the Class name field, enter a unique name for your class.
A class name can have the maximum length of 56 characters.
To show the relationship between classes, use a hyphen in the class name in which the first name is a parent class.
For example: To create a Jobtitles class that derives from an HR class, enter HR-Jobtitles.
Note: Avoid using names that start with Code-, System-, and History-, because the system creates these classes automatically.
In the Context section, select an application layer in which to store your class.
In the Add to ruleset list, select a ruleset in which to store your class.
Optional: To override the default work item that your application associates with this class, in the Work item to associate field, press the Down arrow key, and then select a work item.
For more information about default work items, see Setting your current work item.
Click Create and open.

On the General tab of the class form, select a class type, and then define the class settings for your new class:

Choices	Actions
Define the settings for an abstract class	In the Select class type list, select Abstract. In the Settings section, in the Created in version field, enter the ruleset version that applies to this class, and then go to step 10. Abstract classes have no instances in a database.
Define the settings for a concrete class	In the Select class type list, select Concrete. In the Settings section, in the Created in version field, enter the ruleset version that applies to this class, and then go to step 9. Concrete classes have instances in a database. For more information, see Class keys.

Define the class group settings of a concrete class:

Choices	Actions
Create a class group	In the This class list, select The class is a class group. Result: The Class group field autopopulates with the class name. Optional: To encrypt the Storage Stream of each instance of this concrete class when saved to the PegaRULES database, and to decrypt the Storage Stream when an instance is retrieved from the database, select the Encrypt BLOB check box. For more information, see Encrypting the storage stream (BLOB). Optional: To define key parts of the class, in the Keys section, provide a key name and a caption. For more information about class keys, see Class keys. Optional: If you provide only one key, to ensure that instances of this class are unique, and to automatically supply a globally unique value for further new instances, select the Automatically generate a unique ID for records of this type check box.
Define the settings for a class that does not belong to a class group	In the This class list, select does not belong to a class group. Optional: To encrypt the Storage Stream of each instance of this concrete class when saved to the PegaRULES database, and to decrypt the Storage Stream when an instance is retrieved from the database, select the Encrypt BLOB check box. For more information, see Encrypting the storage stream (BLOB). Optional: To define the key parts of the class, in the Keys section, provide a key name and a caption. For more information about class keys, see Creating classes.
Define the settings for a class that belongs to a class group	In the This class list, select belongs to a class group. In the Class group field, enter a class group name that you want to include this class. Optional: To encrypt the Storage Stream of each instance of this concrete class when saved to the PegaRULES database, and to decrypt the Storage Stream when an instance is retrieved from the database, select the Encrypt BLOB check box. For more information, see Encrypting the storage stream (BLOB).

In the Class inheritance section, define how the class that you create inherits rules from superclasses:
1. Optional: To use pattern inheritance before direct inheritance when the system finds rules at run time, select the Find by name first (Pattern) check box.
  Pattern inheritance searches in superclasses based on prefixes to class names that end in a hyphen.
2. In the Parent Class (Directed) field, enter the class name of the immediate parent of your new class:
  For concrete classes that are class groups, enter Work- or a class that inherits from the Work- base class, or enter History-Work- or a class that inherits from the History-Work- class, if you create a class to hold the history of work items.
  If you enter the longest possible prefix for your new class ending in a hyphen, you can select or clear the Find by name first (Pattern) check box, with no difference in rule resolution behavior or results. For example, if you create a Work-Object-Mortgage class and the parent class is Work-Object-, the system performs the same search regardless of the check box setting. Avoid using System- and Code- base classes, because these classes are reserved.
  Note: During rule resolution, the system considers only direct parent classes. For example, class C inherits from class B, and B inherits from A, but C does not inherit from A.
Click Save.
Optional: If you create a concrete class, check the class connection with the database by clicking Test connection.
Note: For the test connection to work, ensure that the JDBC JAR file for the database platform is present and included in the classpath, and that the prconfig.xml file contains an entry for the database driver. For example, <env name="database/drivers" value="org.postgresql.Driver" />
Result: A window that contains the test results opens. The results include whether the class is abstract or concrete, and the database and database table if the class is concrete.

Naming conventions for classes

Unified naming standards for classes help you manage your resources in a logical and efficient way. You can avoid duplicating your content, maximize efficiency, and speed up application development by sharing resources between multiple classes or class layers.

For example, you can create class names that support class inheritance, so that you can reuse resources across different classes. When you name a class ReviewRequest-LoanRequest, you indicate that a new class LoanRequest inherits resources from the ReviewRequest class.

When you name classes, consider the following guidelines:

Use a noun for a class name, for example Customer or Address to distinguish classes from actions and processes. For better readability, capitalize the first letter of each word, for example, CustomerAddress.
Ensure that your class name is descriptive and clearly conveys the purpose of the class.
Avoid using acronyms and abbreviations that are difficult to decode. The exception are common acronyms, such as HTML.
Avoid including underscores (_) in class names.
Pega Platform provides a set of base classes that includes the Work-, History-, and Data- classes. Create new classes only under the organization base class, for example, UPlusTelco-.
The system displays labels for class names on some of the forms, worklists, reports, and other areas of an application. The system also displays a short description for the class. Therefore, use class names that are self-explanatory and reflect the purpose of the work. Avoid using class names that reflect a status or action, instead of a unit of work.
Choose class names that support pattern inheritance, as well as directed inheritance. For more information about class inheritance, see Understanding class hierarchy and inheritance.
To distinguish hierarchy position and inheritance, use class names that visually reflect pattern inheritance. For subclasses, include the names of all parent classes, including your top-level class, separated by dashes. For example, if the parent class YourCoLoan-Request includes child classes for mortgage and car loan applications, name the child classes YourCoLoan-Request-Mortgage and YourCoLoan-Request-Auto.
Name related objects with consistent prefixes, so that you can quickly locate similar classes in an alphabetical list.
Use the same naming conventions for class groups as for classes.

Class keys

When you define concrete classes, you can add keys to identify the classes. You can add the keys when you create a class, or you can update the keys later.

Every instance of a concrete class includes a key formed from the value of the properties that the class contains. The value is unique within the class or class group. For example, your system can contain only one instance of the Data-Admin-Operator-ID class with an ID value of SampleID. Similarly, your system can contain only one HTML fragment rule named MyFragment in the same ruleset and version.

The properties that form the key might apply to the concrete class itself, or to a parent class. For rule instances, the system appends the ruleset and version as part of the internal key.

Pega Platform looks in three places to learn which property values to connect to, and in what order, to form the unique key. The system assembles keys the first time it saves an instance:

For a concrete class that does not belong to a class group, the system first examines the Keys array of the Class form. If this array is not empty, it forms a key by connecting the values of the properties identified in that array.
If the Keys array of a class is empty, the system uses class inheritance to locate a superclass for which the Keys array on the Class form is not blank. When the system finds such a class, it connects the values of the properties in that Keys array, and forms the key.
For a concrete class that does belong to a class group, the system forms a key based on properties in the Keys array of the Class Group form. As a result, the system ignores any information in the Keys array of the Class form.

When you add keys to a class, consider the following factors:

The system creates both a new class and single value properties of the Text type when you enter the property names into the Keys array, before you save the Class form for the first time. If you want to apply one or more already-defined properties as key properties to a super class of this class, enter the already-defined properties after you save the Class form.
For concrete classes derived from the Log- base class, the property pxCreateDateTime is usually the final or only key part. In some high-volume systems, two log events might occur in the same millisecond. If this can occur in your Log- class, choose additional properties to ensure uniqueness.
For concrete classes derived from the Index- base class, enter the properties pxInsIndexedKey, pxIndexCount, and pxIndexPurpose in that order. Avoid using any other properties in the key.
For external classes, use of properties with a Type value of Date, Time, DateTime, or Double as key parts might introduce rounding or uniqueness issues. Review the data representation on the external database that you use, to confirm that it maps one-to-one with the Pega Platform representation.
If two or more properties form the key, the order of rows in the Keys array is significant. Consider which order is likely to produce a natural or frequently presented sort order in reporting or searching.