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Unlocking the Power of Expressions in Pega

Expressions form the backbone of functionality within Pega, empowering users to perform diverse operations and computations. In this post, we'll delve into the intricacies of expressions, exploring their structure, utility, and practical applications.


Understanding Expressions:


At its core, an expression is a singular text element that yields a string value when executed. In Pega, users harness expressions to create both SQL expressions (or functions) for report definitions and Java expressions for activities and other rules.


Expression Composition:


Expressions within the Pega Platform bear resemblance to formulas in Microsoft Excel but are grounded in Java language conventions. Users have the flexibility to either manually input expressions or utilize the Expression Builder, a tool that guides them through the process. These expressions can encompass constants, property references, arithmetic and logical operators, parentheses for evaluation order control, and functions.


Operations Supported by Expressions:


Expressions in Pega enable a plethora of data operations, including mathematical calculations, property value comparisons, text manipulation, data transformation, and data type conversion (casting).


Where to Use Expressions:


Expressions find their utility across various rule forms within Pega, including activities, data transforms, Constraints rules, and other places where computation of values occurs at runtime. The type of expressions permissible depends on the behavior of the rule form's fields and their allowable entries.


Examples of Expressions:


Expressions in Pega span a wide spectrum, from simple constants to intricate property references and function calls. Examples include constants, single property references, aggregate property references, linked property references, arithmetic and logical operators, and function calls.

Expressions provide a wide range of computations.


Practical Applications of Expressions:

  1. Constants: Representing simple literal values.

  2. Property References: Identifying specific properties within the application context.

  3. Arithmetic and Logical Operations: Performing mathematical calculations and logical evaluations.

  4. Function Calls: Invoking built-in, standard library, or custom functions to execute specific tasks.

  • Constants - An expression can be as simple as a single literal constant. 1. "Good Evening" 2. 525 3. true 4. 20050705 5. 0x143F871A

  • Single Property References - An expression can reference a single property, identifying the page on which it is found. In the context of an activity, an expression can reference a parameter or local variable. 1. .Price 2. Parameters 3. MortgageLoan.Application.ZIPCode 4. primary.pyLabel

  • Aggregate Property References - You can identify aggregate properties or parts of aggregate properties. (The property mode of the target must match the result of the expression.) 1. MortgageLoan.Application.Address(4) 2. Globe.Division(7).Unit("West") 3. Invoices.pyOrders(2).pyItems("Manuals").pyItemNames

  • Linked Property References - You can identify properties accessed through linked properties, using the syntax .property1.property2., where property1 is the linked property and property2 is a property reference in the linked class. 1. .pyUpdateOperator.pyLabel 2. .pyUpdateOperator.pySkillsPrimary(6)

  • Arithmetic, Logical, and Comparison Operators - You can use most Java operators for arithmetic, string operations, comparisons, and conditions. Use parentheses to control the order of evaluation. 1. .Price * (1+(.Tax/100)) + ShipInfoPage.ShippingCost 2. .pyEffortActual >= .pyEffortForecast 3. 3.14159*.radius *.radius

  • Function Calls - Your expressions can call built-in functions, functions in standard libraries, and custom functions. 1. @SUM(.SubComponents().Price) 2. @Pega-RULES:MapTo.Function(argument1, argument2)

  • All Combined - Expressions can incorporate all the elements described in this topic together. 1. @SUM(.SubComponents(38+.Offset).Price)


Conclusion:


Expressions are indispensable tools in Pega, facilitating dynamic computation and data manipulation. Understanding their nuances and leveraging the Expression Builder empowers users to streamline processes, optimize workflows, and unlock the full potential of the Pega Platform. Stay tuned for our next post, where we'll explore the practical aspects of building expressions using the Expression Builder.


-Team Enigma Metaverse




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