In Constellation, the modern DX architecture has changed how the UI initializes data. Traditional Harness rules are no longer used to process the UI, meaning that initialization activities or data transforms historically configured on a Harness will not execute at runtime.
To set properties or initialize data when a Landing Page loads, you must shift your logic to the application’s UI pages class context.
The Recommended Approach
Because Constellation relies on a stateless, API-first architecture, landing page initialization is handled via a global Data Transform.
Step 1: Create or Update pyDefault
Locate or create the pyDefault Data Transform in your application’s UI Pages class (the specific class context where your Constellation landing pages are defined).
Important Note on Scope: This
pyDefaultData Transform will execute every single time any landing page in the application is launched.
Step 2: Conditionally Target Your Specific Landing Page
To prevent your logic from running globally and restrict it to a single target page (e.g., a “Supervisor Landing Page”), you must isolate it using the dynamically passed parameter pageID.
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Add a precondition or a conditional
Whenblock to your step. -
Use the logic:
Param.pageID == "YourSpecificLandingPageID"
How to Find Your Landing Page’s pageID
Generally it is the rule name that is created for your landing page. It can be identified here:
If your properties are not being set if we use above id, you can intercept it using the Pega Tracer by following these steps:
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Open the Tracer tool before navigating to your page.
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Click on your custom landing page in the user portal.
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In the Tracer, look for the following REST API endpoint call:
Resource: /application/v2/pages/LandingPage -
Click into any step within that event execution and open the Parameter Page. You will find the exact
pageIDstring value listed there, which you can use in your conditional logic.
Example Scenario
If you have a widget on a landing page that requires four properties as inputs, you need to set those four property values on the specific page where the landing page renders.
As shown below, you can add a When condition checking the pageID, then set all four properties:
In the Tracer, you can verify that the Data Transform executes and successfully sets all properties:
Once configured correctly, the widget will load as expected because the required input properties are fully populated upon landing page initialization.
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