How to Pass a Variable from One Apex Class to Another?

Question

I have an Apex class (MyCTIExtensions) that retrieves a phone number and stores it in a static variable (phoneNumber). When certain conditions are met (cases.size() > 1), the class calls a Visualforce page. The Visualforce page’s controller (FlowRedirectController) is supposed to retrieve this phoneNumber and use it to construct a URL for a Flow. However, the phone variable in the second class is not receiving any value.

Why is this happening, and how can I correctly pass the phone number between these two classes?

Answer

The issue occurs because Apex is stateless between transactions. Creating a Visualforce page via a URL and subsequently a Flow via another URL results in a new transaction, meaning that static variables do not persist across requests.

To correctly pass the phoneNumber from MyCTIExtensions to FlowRedirectController, we need to pass it explicitly via the URL instead of relying on a static variable.

Step 1: Modify MyCTIExtensions to Pass the Phone Number in the URL

Instead of storing the phone number in a static variable, append it as a URL parameter when redirecting to the Visualforce page:

if (cases.size() > 1) {
    dataToReturn.put('url', '/apex/RedirectToFlow?phone=' + EncodingUtil.urlEncode(phoneNumber, 'UTF-8'));
    return JSON.serialize(dataToReturn);
}

Step 2: Update FlowRedirectController to Retrieve the Phone Number from the URL

Since the phone number is now passed in the URL, retrieve it using ApexPages.currentPage().getParameters() instead of the static variable:

public class FlowRedirectController {
    public PageReference redirectToFlow() {
        // Retrieve phone number from URL parameter
        String phone = ApexPages.currentPage().getParameters().get('phone');

        // Construct Flow arguments
        String flowArgs = '[{"name":"Phone","type":"String","value":"' + phone + '"}]';
        String encodedFlowArgs = EncodingUtil.urlEncode(flowArgs, 'UTF-8');

        // Construct the Flow URL
        String flowUrl = '/lightning/page/recordActionFlow?lightning__flowDevName=CTI_ScreenFlow_GestionDeContactosMultiples&lightning__flowArgs=' + encodedFlowArgs;

        PageReference pageRef = new PageReference(flowUrl);
        pageRef.setRedirect(true);
        return pageRef;
    }
}

Explanation:

1. Why was the phone number lost?
   Since each HTTP request in Salesforce creates a new transaction, any static variables (MyCTIExtensions.phoneNumber) do not persist across requests.
   The Visualforce page and the Flow are being opened via URLs, meaning a separate execution context is created, losing the stored value.
   
2. How does passing the value in the URL fix the issue?
   Instead of relying on a static variable (which does not persist across requests), we explicitly pass the phone number as a URL parameter (?phone=...).
   The Visualforce page retrieves the phone number from the query parameters (ApexPages.currentPage().getParameters().get('phone')).
   
3. What is the expected outcome?
   Now, the phone number is properly passed from MyCTIExtensions → FlowRedirectController → Flow, ensuring that data persists across the different transactions.

This approach guarantees that the necessary data is available throughout the process, solving the issue of the lost phoneNumber variable.

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