List has no rows for assignment in visualforce controller

Question

There is a weird behaviour when referencing a visualforce page.

I have a screen flow and I'm testing an Apex Action using @InvocableMethod. My method receives a List of Ids, and I use those to get a visualforce renderAs="pdf" that will render content using fields of each record, and insert them as attachments:

    @InvocableMethod(label='Adjuntar PDF')
public static void adjuntarPDF(List<Id> presupuestos){
    List<Attachment> adjuntos = new List<Attachment>();

    for(Id presId : presupuestos){
        System.debug('presupuestoId ====> ' + presId);
        PageReference pdf = Page.PDFPrueba;
        pdf.getParameters().put('id', presId); 
        Attachment adjunto = new Attachment();
        adjunto.Name = 'PDF PRES';
        adjunto.Body = pdf.getContent();
        adjunto.ParentId = presId;
        adjuntos.add(adjunto);
    }

    insert adjuntos;
}

Visualforce controller:

public with sharing class PDFPruebaController {

public String presupuestoId;
public Quote presupuesto {get;set;}

public PDFPruebaController() {
    presupuestoId = ApexPages.currentPage().getParameters().get('id');
    System.debug('presupuestoId visualforce =====> ' + presupuestoId);
    presupuesto = [SELECT Id FROM Quote WHERE Id = :presupuestoId];
}

}

For some reason, when testing the Screen flow, The apex controller throws a List has no rows for assignment error, when executing the query. The thing is, I logged the Id in the controller to see if it was being passed correctly, and it was, according to the logs:

The Id matches what the flow debugger tells me of the created record.

This is happening when debugging and also when trying to execute the flow normally. Is this an unexpected error, or am I missing something?

Answer 1

PageReference's getContent and getContentAsPDF are treated as callouts. In other words, they happen as a separate, synchronous transaction. As such, a Visualforce page called this way won't be able to see the latest data, which is very likely what's happening here. This is because of transaction isolation, a common feature of many ACID-compliant database systems, including Salesforce.

To fix this, you need to go asynchronous. Add a Pause between the creation of the records and the Apex Action that should read those Id values.

If you read the Triggers and Order of Execution documentation, you'll see that records are given an ID value about half-way through a transaction:

7. Saves the record to the database, but doesn't commit yet.

This sets some properties, and sets a rollback point, but the ID values here don't exist outside the current transaction. It's not until the entire transaction succeeds successfully that those records are released for other processes (including Visualforce pages) to access.